Hi Gail,

I used to design and sell solar PV for residential and small commercial buildings. I also have around 100 hours in the field helping to install them. Some quick answers to your questions:

1. I think it's best to work with a single contractor. In my solar work, I sold the equipment directly to the customer and then arranged for an installation contractor. I don't think the extra effort was worth it, though it may have been slightly cheaper for some customers.

2. The best brands are the ones that have been around the longest, and that qualify for incentives in your area. Here in California, only those modules and inverters on the approved list are eligible for rebates. Then look at verified, independent efficiency ratings, not the "nameplate" output numbers which can vary by 10% or more from their actual output.

3. Maintenance is very minimal under most circumstances:
- Wash off the modules with soap and water as needed (usually once or twice a year). Like a window, they don't work as well when covered with dust, pollen, etc.
- Keep vegetation trimmed back so it doesn't shade the modules, or keep air circulating around the inverter.

4. It does appear that in my area, solar systems do help the resale value. They're also exempt from property tax here.

5. Battery back-up is nice to have, but expensive. I typically only recommended it for those customers who really wanted it, or who were insensitive enough to the cost that they'd buy it just for the peace of mind...particularly in areas where the grid can be down for several days to a week in the storm season.

6. Not really. Customers should budget to replace their inverters every 10-15 years however, because they do wear out. Their longevity depends on how well they're made, and how they're loaded by the PV array. For better longevity, it's better to leave a little headroom than try to max out every string.

7. My former customers are all still very happy with their systems, as far as I am aware.

8. For information on local incentives, installers, and so on, see the Database of State Incentives for Renewable Energy (DSIRE)

Another terrific resource is Home Power Magazine. I've subscribed to it for years. It's always informative with plenty of technical information, and they have some bona fide experts who are very good at responding to reader questions.

I think the best approach is to regard PV as a kind of 'hamburger helper' with the real meat coming from energy savings or other methods. You want to think about all the other things you can do to reduce your draw on the grid in respect of cooking, water heating, space heating and cooling, appliances, entertainment devices and so on. When you've cut back you may even find that PV is enough to eliminate electricity bills. That doesn't make you a tightwad because you can spend the savings on other things and you have prepared for when/if serious carbon taxes are ever introduced.

To give an example it seems silly to run a 2500 watt air conditioner if your best PV output is 1000 watts. You could junk both of them and get a small 150w evaporative cooler powered by the grid and still have lower bills. Do you really need a big screen plasma TV? You could sit closer to a small screen LCD TV. Same goes for shorter showers... you are not really giving up that much.

A new point I would make about PV is that cloud cover seems to work out more important than latitude. Some will say Location X is too far north or south for PV but first I would ask how many cloudy days there are. High thin cloud can cut your power output substantially in otherwise bright conditions.

I'm looking at installing solar PV in the near future, partially encouraged by a friend in this region (Rochester NY area) who has an off-grid battery-backed PV system that keeps his home powered up year round even with the high percentage of cloud cover around here. He has an array of mostly newer Sanyo 200W panels. My preference is to draw power from the grid as required, but not feed back into it, to reduce complexity and eliminate potential problems for the utility (shock hazard from back-fed voltage during power outages). One goal is to build in resiliency in case of future interruptions and outages, so I want a reliable battery system. To extend battery life / maximize return on battery investment, I want to minimize depth and frequency of the charge/discharge cycles, which will involve proper battery management. Part of this will be deliberate shifting of discretionary power consumption to prime sunlight hours, and part automatic via charger management so that charge to the batteries flows from the PV while they are producing, and from the grid when they are not. I would be interested in learning from anyone who has experience in running a system this way.

8. Where does one find good material to read regarding solar PV?

Having lived off grid (in style, I may add) for over a decade, if you are serious about renewables for your home I strongly recommend Homepower Magazine. You can get all of their issues on DVD for $75 (includes a 1 year subscription to the print edition). Many stories by and about folks who have taken the plunge and are living life with renewables. Issues include sections describing the technologies in understandable terms, codes, tax incentives, anything you may want to know. We couldn't have come this far without it. Includes PV as well as micro-hydro, wind, EVs, and other neat stuff. It's also a great history of the grass roots renewables movement, and a great way to know if you are paying too much, or to get in touch with vendors and installers. The best primer there is for renewables. Period.

www.homepower.com

Ditto on the Home Power. I wandered through the bookstore a few years ago with a gift card and came across this magazine and have been a subscriber ever since. PV, Solar thermal, alternative building, all very energy focused at the family/individual level. More old school (no nukes, etc) lefty politics then I care for, but I think it provides humor (inadvertently) as well.

The current fed tax credit (30%) can be applied thru 2016 and applied to multiple years if you do not have enough income to offset it against. Combined with state incentives and if you live in a net metering state, these combine to offer some very attractive incentives.

One word of caution, check your suppliers and installers. This has gotten to be sort of a re-run of the 70's and a "hot" industry where some people who really should not be doing this work are doing it or tying to. So like anything else, ask for references from previous customers and call them to talk about the service they got and how happy they are. PV panels are solid state so you don't have to grease them or change the oil every 3000 miles etc. In the new issue or homepower they discuss maintenance of wind turbines and the parts about checking the wiring and nuts and bolts for the mounting system apply, but even if you were anal about doing this it should be no more than a few hours a year. Lastly, I think paying for monitoring and data logging is important and worth the expense, but I am anal that way :)

Rent or borrow a Solar Pathfinder to be sure you really have enough sun for all the seasons. It's very easy to use once you get your hands on it.

I was all over my city lot and roof looking for a good spot, with no luck :(

Here are links to the Solar Pathfinder and a place that rents it by the week...
http://www.solarpathfinder.com/
http://www.simantick.com/solar-pathfinder-wee-item11605.htm

I read a lot of books on this topic, and Power from the Sun: A Practical Guide to Solar Electricity is the best one I found:

Has anyone successfully used any kind of solar PV generator?

I already have solar heat and hot water, so my south-facing roof space is pretty much used up, and I was thinking about how to deploy an emergency-type system, which might run just a few small appliances, maybe a refrigerator, in case the grid goes down.

Essentially, my hot water systen won't function without power.

Are there any such systems out there?

We have found it practical to use pv for very limited uses-powerung electrical fences , trickel battery chargers, etc.

Many regulars here seem to be in favor of installing residential pv as doomer insurance and others as simply "the right thing to do" in terms of being a responsible steward of the earth.

I understand and respect both points of view.

But I also believe in living and planning by the odds, as I can best estimate the odds to be, and in examining the elephant from as many as possible points of view.

Pv just doesn't add up as yet-a system that would power the essentials at our house, and our house is a modest one, would cost at least forty thiousand dollars and we couldn't count on it, as our food stash is mostly in four large freezers and the farm water system MUST be up.

On the other hand I paid a little over three thousand dollars for a new gasoline powered welding machine that has built in 120 and 240 volt outlets that will power everything on the place, by shifting the load-and one fifty five gallon drum of gasoline will run it for a week just keeping the essentials running, which is the the longest the power has ever been out here-due to an ice storm.

Maybe in five or ten more years the price of pv will fall enough, and the price of grid juice will go up enough,for pv to become practical.

In the meantime, if I had the cash handy I could spend the same thirty or forty thousand on conservation measures that would save probably three times times as much energy as the pv system will generate..We have already done a lot in this respect, installing insulated exterior siding, up graded windows, high efficiency appliances, gravity powered irrigation water,wood fired heat backed up with an oil furnace etc.

When no 2 was cheap we used five hundred gallons or more in the house.Last year we used a little over fifty gallons mostly as a matter of convenience.

There are at least a dozen more things yet to be done that will save a lot more energy per dollar spent than the energy generated per dollar spent on pv at current prices.The next biggie will probably be solar hot water-hopefully the system I eventuyally install will be big enough to make a significant contribution to the residential heat load, saving some wood and or oil.

Of course if you happen to actually have a lot of money to spend on a capital improvement and are afraid tsis going to htf any day, or you just want to make a statement, you should go for it.

But if you aren't overloaded with cash maybe you should spend your money on conservation measures and put pv off for a while-the systems will get better and better , become more standardized, putting out more juice per dollar with less maintainence from one year to the next.Unless you live in hurricane counrty the odds of the power going off for any length of time over the next few years are very slim.

http://i15.photobucket.com/albums/a400/beavercreekfarms/renewable4.jpg

Here's our set-up. We have a dozen Trojan L16RE batteries, and two Trace 4024 inverters. Added solar
water this past summer. Some of our circuits are still on the grid, i.e. elec oven, dryer, heat/air.
Both our 220v water well pumps are on the solar/wind system. In the mid 90s we were w/o power for
11 days during an ice storm. We couldn't flush the toilet or water the cattle since we only have
well water. At that time we started accumulating the parts for our system. Our grid bill is about
100 per month-- or less during the fall & spring. I put the photo link 'cause I didn't know how to paste it in the message.

I have a wind turbine and solar panels – grid tied. I've had it in place for a few years now.
Almost anyone can understand the fundamentals of a solar panel stuffing electrons into a battery. The less obvious part is learning what instruments you need to test things, how to interpret the readings you see, and how to act on that information. Be sure that your installer has a detailed users guide and you have an arrangement for contacting him for assistance. Note that the manual for an inverter is NOT a users guide, you need to know how to set up a schedule for running from the batteries periodically, when the batteries are reaching a critical state of discharge, how to hook a gasoline powered generator to charge batteries when there is no wind or sun, schedule and record checking and topping up the water in the batteries, and how to determine how much power your system does actually generate.

my advice is to wait. wait for price drops (chinese panels). check into gov rebates. the fed rebate is easiest. state rebates have waiting lists and restrictions. i have a 3KW PV system. i paid $25,000 for it. it was the year before the 30% fed rebate. my state rebate at that time had a 3 year waiting list. my advice is to get a 6KW system. there is no maintainence on a solar system. once it is up it is problem free. i had 2 bad inverters. the third seems to be a charm, all on warranty replacement. it is a grid tied system. no grid no PV.

i had my house appraised to sell back in august of 2009. my house still lost 30% of it's value from 4 years ago, that is $100,000! the PV system added no resale value. did not list house for sale. as i did not take my state's rebate the system is mine. if i move i can take it with me. if i took the rebate the system stays with the house. am i satisfied? not sure. you have to pay out the full install price up front and wait for rebates.

do i "save" electric? yes, but not enough. i get "free" air conditioning in the summer. i live in a temperate zone. i find the $3000 i spent installing a wood burning stove was much more cost effective. the stove has already proved itself more practical (comfort and energy savings) than the solar system. stoves have lots of maintainence. the stove added no resale value to my house.

i live in nj. nj offers energy credits to people who install alternative energy. i retired my energy credits as a protest to the way the system operates.

one last thing. i tinkered up some portable solar power generators. they can be seen at:
http://transvue.hi5.com/friend/photos/displayUserAlbum.do?ownerId=446873...

Related question: any input from those using solar powered water pumps? I can deal without electricity for a long time but would miss the water! Is it cost efficient to use it full time instead of electricity? In my part of the world I've been looking at Robison Solar Well Pumps: http://www.highplainsgreenenergy.com/products__services Thanks.

We installed solar PV one year ago and are now able to tabulate a year of results. The contractor we used installs only Sunpower systems, so that's what we have. The contractor was reputable and did a good job with the installation. The cut-over and the sometimes annoying city inspection process was painless on our part. People keep asking me how I like our PV. Well, they just sit up there making electricity. Silently. Nothing to notice. You don't have to do anything except read the monitor occasionally if you want to see how many or how few kilowatts they generated that day. (The monitor is on a wall in our kitchen so we don't have to run outside to look at the meter.)

We calculate after state subsidy, city incentive and federal tax credit our system cost us around $12,000. We had it installed just after we replaced the roof on our house. I have no idea how it will affect resale as housing prices are dropping here pretty wickedly (after truly silly highs), but I notice these days about 10% of my neighbors also have PV panels, so they are going mainstream and may soon be an expected part of one's house.

Our system is 3.0 kilowatts with fifteen panels. The roof of our house breaks east/west, so 7 of our panels face east and 8 face west. When the contractor gave us our original quote, he estimated that our system would average 11.1 kilowatts a day. He was conservative. Last year, over the twelve months, it averaged 12.2 kilowatts/day. This is in San Francisco where we get our fair share of fog, although we do live in the sunnier, eastern half of the city. In June we average 18.2 kilowatts/day. There is a lot of variability. Our best days have been around 23 kilowatts; our worst day a measly 1.5. If we had a south-facing roof, our system's performance would undoubtedly be better, but so it goes.

We do not have a battery back-up. If our power company becomes unreliable, I may consider it. We feed power to PG&E when we produce more than we use. During the summer, if we keep power usage low during peak periods (1pm - 7pm) we can sell electricity to PG&E for $.29 a kilowatt. Partial peak rate (10am - 1pm, 7pm-9pm) we sell at $.14 (or would buy at that rate if we used more than we produced.) Off-peak the rate is $.08/kilowatt. So there is a big incentive to run laundry, dishwasher, etc. off peak. Our "true-up" period with PG&E is an entire year. So the excess electricity we produce in the summer can be used to offset the electricity we buy in the winter. This year, our net purchase of electricity came to about $10. We are also charged a monthly fee for the "privilege" of being hooked up to the grid. We also, as of now, can't sell back more $ than we use--i.e. PG&E will not pay us money if we sell to them more $ worth than we buy from them. I believe there is a law the governor signed recently that may change this in California so that solar PV owners will get paid for all the electricity they feed into the grid.

As I said, our average electrical production/day last year was 12.2 kilowatts. Our family's average electrical use/day last year was 14.94. So our solar PV did provide the majority of our electricity. We added solar hot water in December (the worst possible month performance-wise) which has converted our main hot water tank from natural gas to solar with electrical back up, which may up our electricity usage significantly in winter months. I'll have to let you know later what kind of performance we get out of it. I would like to lower our electrical usage back down by converting CFLS to LED bulbs as the technology improves. (I wish someone would make an energy efficient candelabra bulb that didn't look as ugly as a Dr. Who dalek.)

Here are some real costs I pulled up in response to a post from Scotland last night regarding a system for charging an EV. Add another inverter and you would have a nice off-grid system (or grid parallel system) if you are handy enough to do the install. Just an idea of component costs today.

Strob,
If you figured $30,000 for 3120 watts of panels you guys are paying about 2-3 times what we are in the U.S.. I can get a pallet of 28 200W panels for under $2.50/watt. (5600 watts = $14,000) Looking at top rated Kyocera 210W at $3.11/watt ($706 each). $12,708 for 18 panels = 3780 watts (rated). An order that large will probably get you free shipping in the lower 48. Depending on voltage, charge controllers would be less than $2000. Rough figure for good batteries (about 42 KwH) and a good inverter about $9000 max. Balance of system, $1000 (not including panel mount).
Grand total: $24,708 (and with some arm twisting even less). I just wanted to give folks an idea of what a good system for charging an EV in the U.S. may cost. Around $25,000 (plus install and mount) will charge your EV for years and provide a good backup system for your home. Panels are at historic lows in the U.S. right now. I'm sorry to see they're so high across the pond. Maybe you should shop around some.

Edit: found same panels for $628 (Kyocera KD210GX-LPU 210w)

http://www.affordable-solar.com/kyocera-solar-panels.htm

They have the Schott ASE-300-DGF (290W) for $1157

I have a new solar array from last summer. One thing I did not think about:

If you live someplace snowy, don't forget that the snow can slide off the array all at once because the panels are slippery enough to let it get some momentum. I'll probably need to add some sort of barrier at the bottom of my roof to prevent the snow from crashing down like it has.

Gail
In Australia there has been a strong takeup of domestic grid connected pv over the last year. This is primarily driven by government incentives. Basically the government will subsidise around 50% of the installation costs. In addition our state governments have decreed that owners of small pv systems can earn an inflated feed in tarif on the net amount they feed into the grid each month/quarter. The feed in tarif varies from state to state but is around 3 times the domestic electricity tarif. Based on these incentives, in some cases it makes good economic sense to invest in these systems.

Unfortunately, there are a number of installers that are manipulating the truth when selling these systems to home owners. Two of the scams I have noticed are:
- sellers pretend that a 1 kW system will provide approximately 1 kW of power to the owner on a continuous basis. When pressed they will conceed that the system will provide less than this depending on weather conditions etc.. the reality is that a 1 kW system will actually only provide around 1800 kWhr per year depending on location etc.etc.
- the feed in tarif will only apply if the household produces more than it consumes on a monthly or quarterly basis. For normal household it is unlikely that they will get any return even if they install a 2kW system.

I am sure that most of the reputable pv system providers don't lie about these facts but I know they are very careful with the truth.

I see battery back-up as insurance. My solar installer actually tried to talk me out of it, but I insisted. Modern life pretty much comes to a halt when the electricity goes down.

Here in the Santa Barbara area we had several power outages caused by brush fires. The battery backup system automatically kicked in -- and we were quite the envy of the neighbors sitting in the darkness.

Blackouts of several days, weeks, or months (given a major earthquake, major system meltdown, etc.) will make you kick yourself for not having battery backup.

By the way, the batteries are re-charged by the solar system during the day, so a blackout could last for sometime before the batteries give out.

Well here we go. I'm sure I'll get flamed for this.

PV does not, does not, does not remotely pay for most applications. I've lived with PV exclusively(that means no backup at all) for a decade on sailboats before my current project. My sailboats had no auxiliary propulsion other than sail(and a big oar)and there was no way to cheat. My demands were extremely minimal--I'd run electronics and a boomer stereo(not a purist, mind you.) We're looking at a system that costs probably 2 grand to supply the demands of D cell batteries reliably. That's expensive, but was the only game in down. It worked.

Here in Hawaii, I've just installed for a friend a 1 KW array, which is very small, and his demands are very small too. We've got a drought right now so it's been cracking out the juice like crazy. I've a lot of respect for the OUTBACK gear in general, and probably wouldn't go with anything else. My boats, however, were 12dc and direct wired with big batteries and charge controllers were me with a toggle switch. The 1 KW array is a 10 grand project at this point, having just finished one to DOD specs.

My Honda EU 2000 here in Hilo Hawaii was 1100 bucks with tax. It burns a gallon a day if its also running a hot water heater. It will run on papaya E90 just fine. I've got a far far better chance of keeping the Honda running and getting parts than I do trying to electo-flux bad cells or fixing the guts of a high tech inverter. Tearing down the generator or even rewinding the alternator isn't that intimidating. The alternative is impossible. PV is a completely non-renewable renewable at this point.

What's more more sustainable? The generator, easily, and by a lot. We haven't discussed batteries. I'd much rather store power in a stable form(E90 or better) than try to keep a 3000 dollar battery bank charged. Really, I don't think there's any other way to spin it.

A bit of a diatribe, but I stand behind it if you crack the math on an individual level.

For those looking to purchase--here's a tidbit of advice. It's really hard for someone having dropped 20k on a system to admit whether it works or not. If you're looking for advice, limit your input to those who have lived on PV exclusively(no grid or generator backup.)Don't get me wrong. PV works. If it's the only option, it's a great option. In my experience, does it make sense or is it sustainable? Hell no, would be my response.

What I can share...

In California, the solar industry is already pretty mature, IMO. The rebates are complicated and so the solar installer walks the client through the process. Different jurisdictions already are developing their particular solar code requirements. Contractors seem to be able to get a substantial wholesale price advantage on modules. For the three reasons just stated, DIY is generally not the way to go for anything but small off-grid applications.

Storms are not a big issue in cities here, so for the time being people are not concerned about the grid going down, and battery backup would be rare except in rural areas. taomom's experience is probably the pretty common for people who've installed solar recently. Around here, getting a good deal on solar is becoming like getting a good deal on having your house repainted or your roof redone; It takes about as long, and the hard part is finding a solar contractor you can trust.

After I pushed my parents to install solar for a while, a neighbor of theirs suddenly started pushing for a group of homeowners on the block to install solar. They were offered a substantial group discount (~%30, I think) by an installer that focuses on residential systems. (This may tell us something about how much of the cost is profit for the company owner.) My parents have now had their 2.1 kW system for about three months, which is too soon of course to posts results, but I'll be keeping tabs on it.

I'm a PV holdout here. Prices keep falling and a PV system could depreciate faster than the savings.

Also there is the issue of highest return on investment: light colored roof in hot climates (painted metal, not asphalt or rough material), good quality windows, extra insulation, high efficiency HVAC and appliances. The cheapest thing is smart house orientation. Have overhangs that shade in summer and gather sunlight in winter. It takes a lot of expensive retrofitting to make up for bad design.

Also, how many square feet do you really use?

Since two members of our household have medical equipment which needs powered, I snagged about 1kw of panels which are still boxed up, and some batteries I keep a trickle-charger on, just so I could get them up if I need to. We'll see if I ever do, but I decided not to take for granted that I could always get them.

Hawaii near sea level doesn't really require much energy for anything, though it is nice to have a fan blowing on a muggy day. I have a couple of second-hand 75w panels that i just throw on the roof to power DC fans directly. I'd like it if I could do the same thing with an inverter and my 110v fans without a battery involved, but they don't seem to be built for it.

Indeed, I like the notion of PV-powered things without the batteries, that run just when the sun shines. In addition to fans, I run a circulation pump in our pond that way. I wonder if there are other battery-less and even inverter-less uses? I think I heard that SunDanzer made a refrigerator that runs with direct connection to PV, but I may have hallucinated it.

A small system for charging device batteries would seem to be a good idea for almost anyone; the difference between "no" electricity and "some" electricity is a big one.

I've lived off the grid for 26 years. If you're completely off the grid and on batteries then I'd strongly suggest that you have the lights that you use most often be either 12, 24 or 48 volts (whatever your battery configuration is) so that if your inverter shuts down YOU STILL HAVE LIGHTS THAT ARE DIRECTLY POWERED BY YOUR BATTERIES. We have solar during the summer and hydroelectric on a small seasonal creek during the winter. During the fall and spring when the days are short and/or overcast and we haven't had much rain, our inverter shuts down whenever the battery voltage drops too low. Since we have 12 volt lights we aren't suddenly sitting in the dark. If you completely depend on your inverter and only have 120 volt lighting, whenever the inverter shuts down your lights go out too.

So what prices are we down to (for panels) ? $/watt delivered ??

what is the minimum Whr/day/person(or household) that is being lived with ?

I researched a while back to install PV on the roof. Decided finally that it was not worth it. Instead I enrolled for "green power" - my utility promises to buy green power to the extent I use electricity. This adds about 10% to my electricity bill.

BTW, here is a very useful link.

http://www.findsolar.com/Widgets/CalculatorEmbed.aspx?t=utility&id=291

You can input your zip code and the amount of electricity you want per month from PV. Using solar insolation etc. it will calculate and tell you how much PV to install and how much it will cost etc. The price of $8/kwh is a little high - but in Seattle to get 500kwh / month, this is my cost - $43K ($28K after incentives).

Well, I've been accused of thinking small, but considering our energy future, that may not be such a bad thing.

http://s831.photobucket.com/albums/zz240/Ingto83/?action=view&current=DS...

This homebrewed little PV- Palm Computer is my answer to the venerable Solar Calculator, using the panel left over from an old bike-flashlight. This HP has only been plugged into the wall once in the last 20 months.. otherwise, when it's running low, it sits on a windowsill. There's plenty of room on that Sill for a Cell Phone, a Voltmeter, a TV remote, Indoor/Outdoor Thermometer and a bunch of other items that still burn through little batteries.

I could do the math against buying AA batts and such, which can actually show a HUGE advantage compared to the cost savings that a Rooftop PV has to mount when going up against the grid, but I think a much more salient issue in this case is the simplicity and independence of these portable devices, which is next to impossible to put a price on. My HP basically NEVER needs an adapter now.. a little dangerous since I have no idea where I left it last year.. but who cares? I can put it in the sunlight anywhere I happen to be, or under a bright lamp if the Sun isn't available.

I do have some bigger PV up on the roof, which feeds isolated systems, like my solar hot air heater, but I really like these little portable items as some of the most interesting applications for Solar PV.

Walkie Talkies - Screwgun Battery Charging - IPhones/Ipods - Lightmeter - Laserpointer - Flashlight - Camcorder - Netbook - Continuity Tester - Guitar Tuner - .....

Bob

We put in our first little PV system about 25 years ago and our 3.6kW system a little over 10 years ago. You can read more about it by searching for my key post A Trip to Todd's. We are not grid tied but are on the grid.

Everyone around here has a back-up generator. In fact, I just bought a new little 2kW one which only burns 1/3 gallon per hour to supplant my 8kW one that burns 1 1/2 gallons per hour under load. There are times when the power is out when only a generator hacks it for us.

A note about batteries - I have 48 L-16's and they are getting tired after 10 years even with desulfonators.

Todd

Reading through there are a few points not yet covered. A friend installed a system for his remote cottage four years ago. A twenty minute fast boat ride -- the nearest grid hydro was over a mile away and would require an underwater cable for most of the distance. Not a real brainer if he wanted electricity without running his generator. To this day his wife still doesn't understand that solar is not the same as flipping a switch as in the city with power for everything -- even Stu didn't viscerally understand the trade offs unless he installed a HUGE system. That would be real costly (still less than the cable hook up). I did discuss all this but....

Last summer they had a lightening strike as did several of their neighbours. His was professionally supplied and installed as were the others. How 'professionally' can be argued but his inverter blew and the back up 6000 watt generator also became toast. His inverter came from 3000 miles away and there was a shipping order error so his solar cells did boo all for nearly 9 weeks. His neighbours had more locally manufactured components and were back up and running in a week.

Surprisingly his insurance covered 100% of all replacement costs --- no depreciation for even the nearly 10 year old generator. 'Course his insurance premium has risen by nearly $1,000 for each of the next 6 years.

6. Are there any particular issues with inverters that readers should be aware of?

Inverters convert direct current to alternating current (PVs produce DC, the grid is AC). With inverters, as with most things, you get what you pay for. Inverters produce AC power in different ways. Cheap inverters (like most car inverters that you plug into your lighter or hook to your battery) produce a "stepped" waveform to mimick the true sine wave that grid AC power has. More expensive "true sine wave" inverters produce a waveform that is (nearly) identical to the grid's waveform and frequency. Many electronics, CFLs and anything with a clock that counts cycles don't like the cheaper "modified sine wave" inverters. Premature failure is often the result. Any utility approved grid-tie inverter will be true sine wave. Most of these will also include the electronics and connections for the PV array.

Off-grid inverters are designed to be connected to a battery or bank of batteries. Many also have connections for generator power, grid power (if you have it) and are battery chargers (a battery charger is an inverter working in reverse in this case). A good off-grid inverter will be programable to do a lot of things. They can be set to autostart a generator or charge the batteries from the grid if your batteries get low. They can also control other equipment. The DC voltage of off-grid inverters range from 12 vdc to 48vdc (with a few exceptions). These inverters come in 120 and 240 vac versions 50 or 60 Hz. They can also be stacked and combined for more power:

One thing to remember about battery connected inverters is that they can pull a lot of amps. An inverter producing 1200 watts from a 12vdc battery is using 100+ amps(amps X volts = watts), so you need big wires. Proper fusing and wire size is critical. Many fires have been started by folks that didn't understand this. I use 4/0 welder wire for my battery cables. Always use copper! Keep your battery cables short! Your inverter should come with cable specs or your supplier can sell you the right ones.

A good inverter is more than 90% efficient at converting DC to AC.

A third category of inverter is sort of a hybrid of the off-grid and grid-tied inverters, called grid-interactive.

http://www.outbackpower.com/products/sinewave_inverter/grid_tie/

They can allow you to be off-grid and sell only your extra power to the grid. They can also be programmed to top your batteries off from the grid during off peak periods, and other neat things. You can store power when it's cheap and use it during expensive peak times. Not sure of the EROI of this, though.

We have 9 KW of PV solar (Kyocera panels), plus a solar water heating system that I bought as a kit and installed myself for about $3K. The system is grid-tied with 12 KWH of battery back-up. It produces about 13,000 KWH per year, about equal to what we use; the house is all-electric. I am happy with it. Still thinking of adding another 3 KW for charging electric vehicles; I currently commute to work using an electric bike and regular road bike.

An electrician installed an "emergency subpanel" that is connected to the solar inverter (Xantrex 6048). This subpanel covers the house lights and outlets, refrigerator, microwave, a few kitchen outlets. If the grid fails, the battery backup powers the subpanel. Not covered are the electric stove, air conditioner, dryer, electric backup for the water heater.

I have an EE degree and a computer science PhD, but by the time all the above stuff was included, it really was rocket science, and I'm glad that Texas Solar Power installed it.

We recently had an outage of the whole neighborhood lasting about 45 minutes. Switch-over to the backup system was completely seamless: the only reason we knew about the outage was that my wife asked why the clock on the stove was not working; then I went outside, and the whole neighborhood was dark except for our house.

A lengthy grid outage is a real possibility. There is about a 2% chance each year of a large solar flare and electromagnetic pulse that would likely take out the grids in the northeast 1/3 of the US plus the Pacific northwest. It could destroy the large power transformers, which could take years to replace. Without electricity, of course, you lose gasoline pumps and lose water after a few hours, and without water you can only live a few days.

Is it worth the cost? I think so. Does anyone reading this site think that electric power will stay cheap? Austin Energy has a great local rebate program, plus there is a 30% Federal tax credit. With those, our system has a payback time of around 12 years at current electric prices (about 10 cents per KWH). Look at that another way: I have a safe bond that pays 8%, tax free, inflation adjusted, and
hedges my energy cost for the rest of my life. Wall Street types would kill for such an investment.

Reducing your electrical consumption down to where you can afford the PV is the answer.

Most folks do not/ will not do that and will remain on the grid

Currently most PV systems are for those who make enough money that they can use a tax write off , or folks who are to far out to get the grid.

An example .....
Simple Solar Homesteading

http://www.freewebs.com/simplesolarhomesteading/photos.htm

I've heard that Solano country vineyards have had hundreds of ground mounted panels stolen. In my case on a residential roof, State farm didn't batt an eye -or raise rates to add my system onto the homeowners policy. But if you are in a remote area, that theives might think makes a good target, it might be an issue. The contractor, was in a big hurry to move the panels off his truck into the back yard, as he didn't want someone driving off with them. (And I live in a pretty safe neighborhood).

We decided to see what you could do at the frugal end of the spectrum, and have now been off the grid for five years.
Total set-up cost NZ $3,200 (perhaps $2,000 US). One (yes one) 50 watt panel powers the house, only needs a kick in the pants if we get 4 or more sequential cloudy winter days. It peaks at 3 amps, and we track the sun (tilt, rotate, and seasonal inclination)- much more efficient. House is 12 volt, all lighting homebuilt LED'S plus the odd Cree. Batteries are ex computer-backups (4 x 65 amp/hr, sealed lead/acid) still going strong. They chuck them out after 18 months, and they've spent their whole existence fully charged. You get them for scrap value.

The trick is if you don't have an appliance, it doesn't use power!

Washing machine and vacuum cleaner are 240v ac, for which we fire up the 'genny', and charge up everything in sight at the same time. Petrol costs average $1 NZ / day. I'm working on a 12 volt drive for the w/m..., and a pelton-wheel in the creek driving a GE washing-machine motor (reconfigured star-to-delta) will replace the 'genny' soon. Fridge is 12 volt and top-loading, the body of it is outside the shady (our South) wall of the house, but accessable from within.

The house draws, full noise, about what our inverter does idling (which is why we don't invert). 1.5 amps......(wait for the yowls from the disbelievers!) The only thing that overtops that is cranking up the stereo Real loud.....so we tend to do that on sunny days. Thick cable is the antidote to running a low voltage.

Compared to the $30,000 to get grid-power to our site, we were ahead from the word 'go', and anything under 50 volts doesn't need a permit, or a 'sparky' to install it, hereabouts.

My first PV panel, bought for a boat in 1980, still put out the 7 watts it did back then, nowadays powering an electric fence. They last if not physically abused, although some (early BP panels in my experience) tend to drop in output a bit over time.

You do, though, as somebody above pointed out, need a partner on the same wavelength.

From a UK perspective solar is beginning to be interesting. I'm about to contract for a 1.67kw grid-tied system that should generate about 1500 kwh pa. Until end of March system attracts a grant of £2500 and govt are introducing feed in tariffs in April of 36.5p per kwh generated plus 5p per kwh exported. With roughly 60% of generated electricity replacing part of my annual use of 4500kwh the total annual return of £667 on net capital cost is 11.24%.

We built in Lorraine (North East of France) a low energy house with a lot of technologies including solar PV panels.
We are living in since mid 2008 and for the year 2009 we have all measurements.
32 m2 of panels have produced 4 074 kWh. The max in summer was 28 kWh per day, in winter 10 kWh per day. Panels are Kyocera and inverters are Fronius (Austrian manufacturer). The house itself and the PV systems were installed by a German company (Weberhaus.de). Cost for all PV material and installation was 30 k€ and we had 7k€ from the government as incentive. The estimated pay back time for energy return is around 3 years and for cost it is around 17/20 years because here the kWh is paid 3 times more than the grid tariff, 0.33€ kWh instead of 0.11. To better understand the day to day production, I installed outside temperature sensor, panel temperature sensor as well as insolence sensor. I have a data card storing measurements every 20 min, it is very interesting for me to have real data as I’m giving lectures about this overall project.
For our global energy consumption in 2009 we are at: 16.7 kWh /m2/y all energies (wood, gas, electricity produced and used for all purpose). The house is 196 m2 (2 110 sq ft) with a Prius 2010 in the garage (waiting for the plug in version…). For the carbon foot print we are very low (1 kg /m2/y) thanks to a green electricity contract (hydraulic along the river Moselle) with a local provider.
For people interested I can send the pdf one page summary of the project, so let me know.
The web site of the International Energy Agency dedicated to PV is very interesting for worldwide informations and documents.
http://www.iea-pvps.org/

http://www.digistash.com/data/026a39ae63343c68b5223a95f3e17616/7882_p125...

(tried 6 different ways from Sunday to get the photo to post, and can't....so go to the link if you want to see my setup )

We put in a 2kw system on 2 active trackers I built ( about $600 in each mount )last December, then added another 1kw in May. It generates about 250-300kw/hrs/month. Grid tied with battery backup. All self installed, about $20k in the system. Battery is a 1200amp/hr AGM unit surplus from a cell phone company ( cost-$100....seriously )

SolarWorld panels, Outback everything else.

I did it since I believe long term, the grid won't be around, and this will give us enough capacity to run refrigeration and lights.

We are on TVA electric system, and they have a good infeed tariff ( 0.21/kwhr ) for all you produce on solar ( 10yr contract ) + $1000cash payment on completion of install....combined with the 30% Fed credit, I figure we have about 13k out of pocket....and last month's electric bill was 20 bucks. Still a long payoff, moneywise, but peace of mind is worth a lot.

Power was out for 3 days just before Christmas (heavy, wet snow ), but not for us....manual transfer switch in the garage, and most of the house runs just fine !

Hi,
I've used a small PV panel while camping, and the little LED indicator lights it has have made me aware of how the orientation of the panel to the sun really seems to make a difference on the power output of the panel. Now I'm thinking about some panels for the house, I'd be interested in anyone's opinions on sun tracking mounts - they have been mentioned in passing in a couple of posts, so if anyone can expand upon their experiences I'd appreciate it.
Cheers, Phil

Emergency conversion of a grid-tied inverter in a power outage?

Hypothetically, if the grid went down for a few days and you wanted the re-enable your grid-tied inverter to power your house somehow, is there any easy way to do it safely?

If you had a generator running and supplied 240ac to the inverter, would it start generating AC again?

I realize the dangers of power flowing back to the grid (which I would disable), but I'm just wondering if there was some easy/cheap way to re-enable the PV array in an emergency at least to run the freezer/fridge for a while, etc.

My family installed a 10K system of PV panels on poles about 3 years ago, and a roof based solar hot water system last year. The former cost $80K, half of which was paid for by federal and NY state programs and tax incentives, and required us to use an certified installer. The latter cost $12K.

Our PV system is grid-tied and has a battery backup. We have two separate electircal panels, one with critical systems tied to solar, and another which just loses power when the grid is down. That allows our house to function longer on batteries. We've never tried going strictly solar for any length of time to see how long the system will last that way. Our installers told us about a week, but I think that was optimistic.

We live in Ithaca, where solarization is very high. There are 5 households with solar PV systems in our neighborhood.

Although we had the money to buy a system, we have had little time to understand it. We can see the difference in our electric bills, and we believe it to be about $150/month on average for the PV -- although the price changes in electric make it difficult to be sure.

The hot water system works amazingly well, for about 8 months of the year. You can see 160 degree water coming in on sunny days on sunny days in November.

We had a significant problem with power fluctuation that would shut down our computers. Our business is in our home, so this was a big deal. It took more than 8 months of haranguing our installer to deal with the problem, and they are personal friends. The problem here in Ithaca is that the demand is so high that the 4 companies that work on it don't return calls for months. Traditional electricians won't even look at the system.

The only other problem we've had is with a super low energy washer we bought recently. It will not do its ultra fast spin when the sun is shining. The chip inside it (or whatever) is so sensitive that our system doesn't provide smooth enough power. The washer stops itself mid-cycle. We've had the installer out and asked for help from PV folks, but have had no luck resolving the problem. We wash our laundry at night and early in the morning -- which sort of defeats the purpose of solar.

Overall I'm very glad we installed our systems, for the added security we have. They take almost no maintenance, except for scraping snow off of panels. For people like us, who have little technical knowledge and little time to learn about the system, it is unfortunately hard to quantify the benefits. I have an Outback "thingy" that is supposed to connect to a computer and report results, but it has sat on the wall in the basement for two years providing information to nothing. We are unable to find anyone with the expertise to hook it up. Hopefully, as the industry progresses these kinds of things will become more routine.

When I retire, or when the SHTF, maybe I'll learn more about my system and be able to troubleshoot it myself.

I'll post the 'hey go buy one panel' solution.

http://www.exeltech.com/pvacproduct.htm

This little device is an AC inverter for one panel. The projected price was to be under $200 a pop.

Seems a company called enphase has 'em also.

http://www.ecodirect.com/Micro-Inverter-Solar-s/245.htm

So one can buy just 1 panel and 1 grid tie inverter and be in business.

(oh and ask your FedGov to add solar panels to the 179 deduction for business)

Before answering any of the questions, it's important to make the most cost effective energy investments first; energy efficiency and conservation. Reducing energy use means far less PV equipment will be needed. Our house uses about 1/4 of the energy of our neighbors, so our PV system costs are consequently 1/4th of that our neighbors would need to install.
Here's a good DVD to help you cut your energy use - Kilowatt Ours

Energy efficiency means that one device will use less energy than a similar one, or energy demand is reduced through other equipment means, such as insulation, weatherstripping, etc. Look at all the old appliances and consider replacing them, especially the refrigerator and the heat pump (or AC), if the home has the latter. Compact fluorescent light bulbs should be installed in the lights that are used frequently (except those that are turned on and off many times in a day).

Conservation means using energy wisely. We don't leave unnecessary lights on, always wait to run the dishwasher 'til it's full, set the thermostat at modest comfort levels, etc. See the DVD for more...

I had a 2kW PV system installed 10 years ago; I bought the equipment through a buy-down promotion for much less than normal, and hired a PV installer to install it.

I don't suggest anyone do it themselves, unless they have very good electrical skills and can properly interpret the codebook in force in their area. Too easy to make a costly or deadly mistake...

1. Is it best to work with someone who both sells and installs solar PV panels? Or is this something that people end up doing themselves, using a variety of vendors?

I would suggest going with one company, and getting one all encompassing quote from them. Only go with certified PV installers.

2. What brands/ types are best?

Major brands with a proven track record, as someone above mentioned.

3. How much maintenance is required?

Next to nothing for the panels/inverter. Batteries are variable, depending on whether they are flooded lead-acid (the most maintenance), gell or AGM (much less), etc.

4. What experiences have people had who purchased solar PV, then moved to another home? Did the addition of solar PV help the resale value?

Not moved yet, though have seen more interest in (and higher valuation of) green homes in this area.

5. What have buyers experience with battery back-up been? Is a small amount worthwhile, even if a homeowner is on the grid?

Depends on a number of factors, such as cloudiness likelihood, amount of power needed during emergencies (i.e., critical loads only), etc.

We have 12 kWhr of battery backup, and it has come in handy after a hurricane passed nearby, knocking out power for 3 days. The first day was cloudy, then the next two were mostly sunny, so we made out quite well (most homes with generators were out of gas by sometime during the second day).

6. Are there any particular issues with inverters that readers should be aware of?

Having had both Trace and Outback, I prefer Outback. Pairing up the inverter and charge controller from the same manufacturer will reduce the number of potential headaches.

7. If you have purchased solar PV, are you generally happy with it?

Very much so. It has encouraged me to 'live within my generation means', as I am net-metering.

8. Where does one find good material to read regarding solar PV?

Home Power Magazine. Purchase the last 12 months of back issues, or buy an online subscription.

Pre wired systems are available

http://www.outbackpower.com/

with battery backup ..

http://www.outbackpower.com/products/smartre/

Just add panels ...

http://sunelec.com/

Maybe a tracker ..

http://zomeworks.com/products/pv-trackers/introduction

http://www.wattsun.com/

You don't need to buy a tracker. Seasonal adjustment can be by 2-3 tilt positions (we just use a bolt through 3 optional holes - every 2 months if I remember. Then tracking becomes (particularly in winter and if you're the wrong side of the 45th parallel) a simple 8-hour arc.

We use an old heavy-duty clockwork mechanism, driving a pinch-roller on a piece of 1/4-inch rope!

Just set it up so it tracks the arc you want in the time you have sunshine. Just a matter of the size of the pinch-roller.

Why waste your scarce energy driving something? Although I guess you can trace the energy we use winding the clockwork key, to some farmer's tractor via our food.......

I read somewhere that the most economical way to do PV (assuming you are starting from scratch) was to buy 12V DC RV appliances and buy panels per appliance minimizing the equipment between the panels and the appliances. In other words, if you start with 12VDC and your end need is 12VDC, there is no need for inverters or any of the other electronic equipment.

Is this approach realistic? What do 12V DC appliances do when the voltage drops too low? Wouldn't that damage them?

We want to have some sort of primitive shelter off the grid and I am trying to figure out the cheapest / easiest way to retain some modern amenities.

I have 4 x 175W panels (in the UK). Two are horizontal, as significant power can be picked up from a cloudy sky if the panel "sees" the whole arc, and two near vertical facing due south. The latter pair provide some power on bright mid-winter days. The system feeds 50V into a 600AH bank of ex-telecom batteries, which drive a 3 kVA UPS used as a 240V inverter. The 240V is used to power fridge and freezer, whose demand matches the sun's power reasonably well, and in emergencies, the oil-fired central heating. The panel arrangement is not optimal for maximum power delivered over a year, but the output is more consistent (I hope).

24V is generated by an auxiliary DC:DC converter, and powers the solar hot water pump circulation pump, this computer, and some LED lights.

Performance: I get about 70% of "nameplate" rating during the summer, and have seen 40% during midwinter, the latter only in the half-hour around noon, however.

The system is not grid-tied.

As an ex-electronics engineer, I don't quite understand the comment upthread about the inverters wearing out, they shouldn't. Their failure rate may be increased by bad line conditioning (lightning, magnetic storms, switching transients) but there are no moving parts (except maybe a fan) so they shouldn't "wear out". My UPS is secondhand, 15 years old and still going fine.

A good website for solar insolation in Europe:

www.satel-light.com

We have 1.2 kilowatts of pole mounted panels at our home in southern Ontario. We are currently having a 10 kilowatt project installed for us on another piece of property we own nearby. Under the recently enacted Green Power Act here in Ontario, homeowners with solar generation capability (up to 10 kilowatts) can enter into a 20-year contract with the utility to sell power to the grid at just over $0.80 per kilowatt hour. The ROI is in the vicinity of 15% per year.

Ontario residents with a Registered Retirement Savings plan (our Canadian equivalent of a 401K plan in the US) can take advantage of some other regulations to enhance the benefits even further. Details in my blog at http://www.juniperrock.ca/wp/?p=57

After several years of lurking this site, I've been drawn in by the home PV issue! Here goes.

We live in southern Maine, one of the worst places in USA for solar. My family has been off the grid since 1983. In the first ten years we went from candles, to Aladdin lamps, to one panel/one battery/and one tail light bulb mounted in a tuna fish can! We kept adding panels and replacing batteries over the years. We are now running with a 1.35KW Kyocera array, 12 L16 batteries, an Outback controller and inverter (sine wave). So, we've come up in convenience, not down. We have an E2000 Honda generator for these darn long, cloudy winters. We have over 2000 square feet. Unlike Bill McKibben's kids, mine have not yet started calling me the Dark Lord, but it's because they think of other rude things to say - and I ignore them as long as they are saying it in the dark ;-) The sun provides insolation, the son provides insolence.

We heat water and cook with propane. We heat the house with wood and some sun.

I like to tell people that once they have gotten their monthly power bill under $20 they are ready for solar. Most of us can barely afford small systems, much less 3KW and up systems. Yet, coming from candles, we feel we are living better than kings of 200 years ago. Indeed, with CFLs, LEDs, efficient washing machine and fridge, we are living better than kings did. Life is good.

I have put the whole thing together myself, although I expect my electrical engineering background made that more possible for me. If you do this, read a ton and visit some sites. There's plenty of information available if you are so inclined.

Batteries stink. There's no way around this. You will likely kill your first set of batteries and then you will keep they next set charged and watered. Someday someone will invent something better and less expensive.

If you can get a pure sine wave inverter, do so. The modified sine wave ones work but cause all sorts of noise in audio, video and telephone equipment. It's now worth the price difference.

I like living with solar. I think my kids (now one in college) get sick of me telling them to turn off the computer by midnight, but it's given them some tiny sense of power and energy. A bicycle generator would have done wonders... My wife is fine with it. She gets it. It was really her idea to begin with, so many years ago.

Maintenance: water the batteries and keep them charged. Watch your power income (sun's up, and no power? must be a line of snow across the entire array!). Change the oil in the generator. My first Honda lasted me well over 15,000 hours and 12 years. I expect the E2000 to do the same or better.

Best wishes to anyone doing this, but don't do it to save money! Like others have said, this is not fast ROI. I could have bought a lot more electricity than I have made with PV with the money I've put into all the gear. But, even if I had power running up to my front porch, I think I do it all over again because it enforces an awareness that few have and that I enjoy having.

I live in Tucson where there is plenty of sunshine. I will have a 12.4 kw system completed by month end. I selected the installer who did my pool heater. He is an MS in EE with 25 years of appropriate experience. There are many start ups out there who are in it for the thrill of having a green job and I fear that their inexperience will kill them or some customer! My system will cost about $74k and after rebates from Tucson electric Power and tax savings will cost about $24k. I am using all German conponents - Solon 280W panels made in Tucson and German inverters -2. I conservatively expect to generate 23,000 kwhr per year and have about a 10% ROI in year one. Tucson Elecric rate is about 10.3 cents a KWhr, is coal based, and likely to see major increases in the years ahead. The panels will last 30 years and are high quality frames - the Germans make good stuff -and the inverters 15 years. Inverter technology is expected to get better and cheaper so that I would expect to replace them for less than I am paying today. I sought advice from industry insiders and was encouraged to buy German, Japanese, or American product. My installer has never had a failure from Solon or Sharp (largest in world). Chinese panels and thin film panels have not demonstrated equivalent reliabilty. But they will get better. Rebate rates are and will continue to go down as hardware and installation costs decline. Now is as good a time as any to purchase the equivalent of an inflation protected bond. I would not consider batteries unless I was off the grid or utility reliability was failing. Cost and product life without the subsidy would not be interesting. Of course the PV investment without the subsidy would also be a joke.
I would like to see the PV companies design a panel that could be repackaged/recycled in 30 years. Another innovation to think about are security fasteners as theft will continue to increase in the years ahead.

Just a general question in response to all the folks who have pointed out how much cheaper it is to run off a small gas/diesel/propane genset compared to solar PV. Isn't this a very BAU way of looking at things? If/when TSHTF I can imagine a certain credit card company running an add something like this.

"Grid connected power $0.56 per kWh.
A backup generator to keep you running when the grid goes down $1500.
fuel for the generator $11.27 per gallon.
A new set of energy efficient appliances and lights $2000.
[pause for dramatic effect}
A off grid PV system for when oil goes over $500 a barrel ...... priceless."

In my case I'm fortunate to have some funds with which to experiment with PV and one of my worries is that I may spend $X now only to find some time in the future that, I could have spent some fraction of $X to get the same results. Chances of that happening? Not very high IMHO. Thew upshot is that if my island nation gets priced out of the oil market and we get into load shedding (rolling blackouts) for want of fuel for the largely oil fired power plants, I will have some electricity most of the time. That brings me to one of my other worries. There's nothing like electric light on a dark night to attract marauding bands of hungry looters, like a moth to a flame!

Alan from the islands

If you've got a decent breeze (10mph+) a fair amount of the time, don't forget the wind generator. Handy for nights/storms when your panels don't work. Even 50 watts (off a cheap 400watt model, which generally don't hit that rating till 25mph+) will run your lights and keep your batteries topped up.

Of course the little ones are kinda noisy. On the sailboat, we turned it off fairly often just to shut it up. Through an exterior wall, especially if not mounted to your house (so no vibration transmission), it's probably noticeable but not really annoying.

I also design, install & maintain renewable energy systems for a living... been doing it since back in the mid 80's before it was the "new greenwashing thing" to do.

DO NOT buy "designs" or systems from one of these money_is_my_reason_for_selling_this_shit.com internet whoresalers. They do not know what they are doing and good luck getting anyone to touch equipment they did not sell, or install and warranty a system they did not design. Ask around and find a reputable contractor that has been doing this for more then 5 years.

Job one is reducing your waste, inefficiency, and consumption. I know it is not popular to talk about conservation... but gigantic, oversized systems on McMansions, to try to compensate for unconscious greed and waste is more of the same thinking that got us into this mess. I will not do a system for a customer until they have done their work first. Most homes can drop an easy 50% off their energy consumption.

Job two is solar hot water. It is much lower tech (and cost) and much more efficient

Lastly, solar PV. There are three kinds of systems:
Grid tie
*Grid tie with battery backup
Off grid

*Battery based grid tied systems are essential for backup during outages, but there is about a 11% efficiency penalty, plus ~25 year life cycle of the batteries to consider.

There (until 2016) is a 30%, unlimited tax credit for RE systems as well as some efficiency upgrades. My wholesale costs are about 50% off of what they used to be... this, along with the federal tax credit means installing a system is about 30% of the price it was about 4 years ago.

Todd

By coincidence, I'd spent a good part of my weekend building a spreadsheet on the cost-benefit of rooftop PV. I came to some conclusions that surprised even me; check out the image below (if a TOD Editor wishes, feel free to archive the images in case they disappear):

Click for bigger versions.

Graph 1: 2010 - 2019.

Graph 3: 2010 - 2040.

Some explanations for clarity:

All prices in Aussie Dollars unless specified.

In Australia, we currently have whats called the Solar Credit Scheme, whereby anyone who installs a PV (or Hot Water) designed by an accredited by the Clean Energy Council can generate Renewable Energy Credits. For the first 1.5kW of a PV system, the credits are multiplied by 5, so if you were entitled to 30 RECs, you'd actually get 150. These phantom RECs are treated by the Market the same as the real ones. You can sell them, to bring the cost of the system down to around $4000 (typically, you sign them over to the installer, and they sell them), or you can voluntarily surrender them/destroy them. Any system capacity over 1.5kW can still generate RECs, but only at 1:1 (no bonus).

In my location, a 1kW PV system can be expected to generate about 4.6kWh/day (barring clouds, solar eclipses, Vorlon planetkillers etc)

I made some assumptions in my spreadsheet:

• A CEC-certified 1.5kW system would cost $4000 after the sale of the RECs.
• A 1.5kW system with a 5kW inverter would cost $5500
• 1.1kW of 60W thin-film UL-certified (but not C-Tick certified) panels cost US$1100 (US$0.98/watt). I allowed several hundred dollars for freight and currency conversion, for a total of $1800. For the purposes of the spreadsheet, I am not generating REC's, and am self-installing (there may be a small fee for a sparky to come out and certify the connections are ok). I use the panels to bring the 1.5kW system up to 2.6kW and 3.7kW.
• A 2.5kW REC-Certified system, fully locally sourced, designed, and installed, would cost $12,000 ($4000 for the first 1.5kW with the bonus RECs, $8000 for the second kW with regular RECs).
• The Tariff 11 (Residential) is 18.87c/kWh (0.19c for spreadsheet purposes).
• The Net Feet-in Tariff is 40c/kWh. Note that this is a Net FIT, not Gross, so you only get the 40c/kWh for production that exceeds household useage. For production below parity, you are only offsetting 19c/kWh.
• No loan is taken out to pay for the system (although Green Loans are available).

For over-parity production (production in excess of household use, thus generating 40c/kWh):

• 1.5kW system pays itself off financially in late 2013, 'pays' $21/week, and pays a profit of $30,000 by 2040 (30 years lifespan, panels are still probably generating 80% of installed capacity)
• 2.6kW system pays itself off finalcially in late 2013, 'pays' $36/week, and profits $50,000 in 2040.
• 3.7kW system pays itself off financially in mid 2013, pays $52/week, and profits $73,000
• 2.5kW REC-certified system would take until mid-2016, pay $35/week, and profit $43,000.

For under-parity production (production less than useage, thus only offsetting 19c/kWh):

• 1.5kW system takes until late 2018 to pay itself off financially, offsets $9/week, and saves $10,000 between payoff and 2040.
• 2.6kW system would take until late 2018 to pay itself off, offsets $15/week, and saves $17,000 between payoff and 2040.
• 3.7kW system would take until late 2017, offsets $22.50/week, and saves $26,000 between payoff and 2040.
• 2.5kW 'local' system would take until 2025, offsetting $15/week, and saves $11,000 between payoff and 2040.

As you can see, whether simply offsetting useage, or actually generating income, all PV systems listed actually end up paying or saving the owner a not-insubstantial amount of money over the warrantied lifetime. I have not allowed for an increase in grid power pricing (expected to rise by 25% this year alone where I live), nor the security of supply in case the Grid become unreliable.

For shits and giggles, I also included a 9.2kW system (1.5kW REC plus 7 pallets of 60W TF panels at 1100W/pallet). I haven't put it on the graphs, but it costs $18,000 pays itself off in late 2012, and pays $130/week!

Now, compare the weekly payback if you had simply put the cost of the PV system into a high-interest bank account or term deposit at 5%pa until 2040:

Graph 2: 2010 - 2040.

1.5kW ($4000) gives $17,000.
2.5kW 'local' ($12,000) gives $54,000.
2.6kW ($7,300) gives $33,000.
3.7kW ($9,100) gives $41,000.
9.2kW $$18,100) gives $81,000. If you put in a 9.2kW system and it generated $130/week for 27 years (after 3 years financial payoff), you'd get a whopping $190,000 in 2040!!!

As you can see in financial terms, assuming the FIT remains, it pays to get the biggest system you can possably afford! If you generate more power than you use, the returns you get from a bank, the Stock Market, or your Superannuation can't touch the returns from a PV array. If the FIT goes, as part of budget cuts or whatever, you can take some excess panels down and sell them. After all, once they've paid themselves off, they're pure profit.

Yet, despite this, I cannot get my Olds to install a PV system. They will pay $8000 for a bus to go travelling in, but won't pay a couple of grand in order to save money, despite whinging about the power bill every time it turns up. They will not turn off lights as they leave the room. They will not turn off some of the four fridge/freezers that are running, mostly empty. They will not replace upright fridge/freezers with chest versions. They will not insulate. Etc etc etc ad naseaum. I have hinted, I have cajoled, I have suggested, I have offered to pay to install myself, I have all but got down on my knees and begged them to, at the very least, install 1.5kW. They will have none of it.

If the majority of the Western population has the same attitude (and I suspect they do), then We. Are. Doomed.

My other halfs family are much more inclined to install PV and undertake efficiency measures, but are treading the fine line of insolvency, and simply do not have the funds to do much of anything. I have begun to hint to them, too, that I would be willing to fund the installation of some PV and SHW if they are unable to get a Green Loan, but no luck yet. Maybe when She gets home from her overseas jaunt (ironically, she was supposed to be on Haiti on Monday when the Quake struck, but bad weather kept her on the cruise ship), I can show the family these graphs and change their minds.