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CA Solar Use Falling Because of Economics
mdsolar writes "The LA Time reports that California is seeing a big drop off in rebate applications for solar power systems. It seems that to get a rebate you have to also switch to a time of use rate with your utility. The math is not working out, especially for smaller systems that don't fully cover use during peak hours. The result: homeowners are reluctant to go with solar energy. 'The difference between peak and off-peak rates is particularly large in the 11 counties of Central, coastal and Southern California, where Edison provides electricity service to 13 million customers. Edison charges summer time-of-use rates that range from 29.7 to 35.9 cents per kilowatt-hour between 10 a.m. and 6 p.m. on weekdays. It drops to a range of 16.3 to 18.6 cents per kilowatt-hour from 10 p.m. to 6 a.m. weekdays and all weekend days and holidays, according to documents filed with the PUC.' There is likely an optimal system size that reduces consumer costs, but with things in flux you'd want some flexibility in your system."
Peak means daytime. Solar only collects power during the day. The issue is that the panels were not collecting enough power to cover peak usage needs. Hence, there is nothing to store - it's all being used, and you still need to buy more at higher "peak" rates.
The biggest problem here is that solar panels are very expensive. You need a LOT to cover your usage unless you have also done MAJOR energy usage reduction efforts such as LED bulbs, better insulation, appliances, etc. If you don't take all those measures, the panel's don't make sense financially.
The math with current photovoltaics will not come out in favour until the fossil fuel rises by a factor of at least 10 times. Does not matter what, how, who, where. They are simply too expensive to provide a reasonable ROI. They also have a very high environmental cost to produce so people who buy them are not doing a lot of good to the environment. Photovoltaics are a gimmick, similar to the hybrid cars which allow metrosexuals and hollywood stars to show off some fake green credentials.
The only working nowdays solar tech for electricity is this: http://news.bbc.co.uk/1/hi/sci/tech/6616651.stm. The tech is originally french (they have been running a pilot plant like this near Marseiles since the mid-70es). For the numbers quoted in the article the performance is quite impressive. 22MW is a small plant, most of them have per-KW cost higher than the normal electricity cost anyway. It is also first of a kind, so cost is inevitably higher like for any new tech. If this is industrialised it should be able to produce electricity at nearly normal costs in any place where you have sun and water to use as a coolant. Plenty of empty land near the coasts around the world to use for this.
Baker's Law: Misery no longer loves company. Nowadays it insists on it
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Storing power is expensive. You'd need a battery charging system and inverter, as well as some sort of system capable of detecting when to switch from charging to delivering power.
;)
Besides, it's not 100% efficient by any means.
16.3 cents per kw/h. Most systems would be lucky to achieve 80% efficiency*, so a 'stored' kw/h would actually cost 20.4 cents. Then there's the fact that most lead-acid battery systems end up costing ~8 cents per kw/h stored, amortizing over their life, because you have to replace them periodically. So you're up to 28.4 cents, vs 29.7 cents for the peak power. Considering the capital costs to install all this, it's not worth it. Drop the efficiency to a more realistic 60% and the costs become 35.2. Youch.
NiMH might be better, but is more expensive initially. LiIon is the most expensive, degrades over time whether you use it or not, but has the highest efficiency.
Now, oversizing your solar panel arrays and having the storage systems so you can go off-grid entirely, also expensive enough that it's probably not worth it. You still generally end up getting special high efficiency DC appliances and doing your cooking and drying with gas.
As a side note, to show the vast difference between areas, my power is ~8 cents/kwh. Off-peak, if I had it installed, is 4 cents including fuel charge. And people wonder why I'm willing to let the californians install this stuff first.
Answer: With my almost absurbly cheap power, combined with very little in the way of rebates, it just doesn't make economic sense.
*Efficiency in this case is a combined metric of battery, charging system, and inverter efficiencies.
I don't read AC A human right
You can save more money if you store energy during the cheap period of the night.
There is a rather interesting alternative to batteries as power storage - unfortunately its a little expensive on setup costs.
Compressed air storage. The same thing you hear is powering those new cars, its also used in a couple of large sclae power stations world wide (one in the US and one in Germany iirc)
The idea is you store air in high presure cylynders, 6000psi 540 cubic feet of air ones are quite good - these are standard and used for filling smaller cylynders (eg for diving) normally. The advantage is as these type of things go they are relatively commodity while being very high pressure. One of these will store about 1Kwh and is about 3' tall and 1' diameter. Lets say you are going to need about 16kWh during the day for lighting and electricy (you won't need any for air con, we'll get to that)
During the night you compress air into these empty tanks (you calibrate the day use to make sure they are empty by the end of the day) Compressing the air generates heat, so you use water to cool this, you should be able to extract enough heat in the water to fill your average hot water tank 4 or 5 times. This can be used for normal hot water, heating a swimming pool or in colder places/times of year for heating (under floor ideally). Compression is about 80% efficient in terms of energy in to potential electricy generating cpacity of the stored air. However factor in the heat you have stored for hot water and you are doing better than 100% - assuming you do use that hot water.
During the day the compressed air is used to run a gas turbine, you should be able to get about 80% efficency again and be able to run a 2-3 kW generator, however the "waste product" is nice cold air - hence no need for an airconditioning system, you just pump this air around your house.
So overall:
During the night you use 24kWh of electricy at cheap rates to store air into 20 of these tanks.
You also end up with about 24kWh of waste heat used to heat your hot water for free - thats definitely your normal hot water use covered, under floor central heating and probably atleast part of your swimming pool if you have one.
During the day you get about 16kWh of useful electricy, plus you get all that nice cold air to cool your house down (about 10,000 cubic feet at a very very low temperature)
Not only do you get a net out of nearly double what you put in, you are also paying less for what you put in that you would if you used that power normally during the day, add a few solar panels and you are laughing.
The draw back?
Cost, you are looking at atleast $40k to install this type of system, plus its not exactly off the self - all the individual components are but you can't just buy it as a package, be nice if it was though!!
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Operating costs of power plants vary, with large coal fuelled plants usually the cheapest and small gas powered plants the most expensive. So you run the baseload on coal and nuclear and switch in the more expensive plants as you need them. In the US in summer highest demand is during the day,so everything gets switched in and the rate is higher. At night you can run on baseload and the cost is lower. There is a lot more to it than that including the effects of energy dealing, but basically that's why solar power makes sense in Ca and Az - you need your power when the sun is shining. In N Europe where our demand is more balanced and the sun is at a lower angle, wind and wave make more sense because they run 24 hours per day (somewhere)
Pining for the fjords
When one buys solar power he is paying for all the electricity costs for 10, 20+ years up front. So when the house does not have enough square footage to provide power through the peak-hours then supplemental power needs to be purchased and the owner of the house is now paying twice for power. Solar power is not rocket science, but people need to be better informed about how the solar power equation works. Finally, until solar power efficiency improves there will be plenty of people who won't have enough roof space to get back their ROI on the investment and thus solar power won't be a popular option until 2 things happen; the panels cost less and are more efficient in coverting light into electricity.
As far as batteries are concerned this is called "power caching" and can be used without solar. I can store all my power for the next day after charging the batteries overnight when the rates are super low - theoretically speaking that is. The solution, before solar, is to sell people "power caching" systems on the grid and then pull that power down during peak times and during brown/black outs.
I love the idea of solar, but until the cost comes down and efficiency goes up there is very little point to struggle with small home systems.
It isn't so much that the incremental cost of producing the power is higher at peak times as it is the cost of capital for an asset that's used less than 10% of the time. What makes life a bit worse is Calif's big FU attempt at deregulation where the utilities were forced to sell off their generation to companies that charge even higher rates during peak times than what the utilities would have done otherwise.The first step that Calif should have taken in deregulation was to phase in time of day power for everyone over a ten year period. This would also make the economics of solar a lot better as the peak output of solar panels occurs during peak load times.
They estimated 22 years to reclaim the investment at $0.42/kWh under Ontario's Standard Offer Program. Which is allowing $0.42/kWh for PV and $0.11 for all other renewable systems.
You can watch the live output stats (requires flash) of the Exibition Palace 100kWh installation in Toronto and see historical data.
The system has been online since last August and they should have a much better month this June, but the 100kW Solar PV installation poorest functional month was 1.8MWh (January) and best was 9MWh so far. At the $0.42/kWh this translates to $756-$3780 per month or 24-121 years to reclaim the investment. At $0.11/kWh this is $198-$990/month or 92-462 years to break even on the investment.
I would think the real annual output will land in the center and at the $0.42/kWh rate, they will reclaim the $1.1 million in around 40 years if the panels output doesn't degrade severely through that period.
In higher annual insolation areas like California and Hawaii with peak electrical usage due to AC, solar PV is getting better for low-maintenance installations like a Walmart or Google roof, when the PR factor is taken into account, but in Canada, it's a long way off from feasible due to the low winter insolation and "Twin Peaks" electrical load with the highest peak in February when solar PV has no real output.
SHPEGS is our attempt to design a more suitable renewable power system for Canada, Northern US and Europe.
Just as a frame of reference, a 32Ah 12v battery is a small car battery. The battery in most cars is around 45Ah. Of course for this application you'd want a "deep cycle" battery that won't be damaged by being run nearly flat and then charged hard - these are sold for caravans and boats. They're more expensive than normal car batteries (about £1 per Ah), but they will last longer in this situation. Some companies actually do batteries specifically for solar power applications, but I don't know what makes them different from normal deep-cycle batteries.
I'm in exactly the situation described in the article. I've gotten my first quote on a solar system, and will get my second quote next week. I'm trying to figure out if the whole thing makes sense financially, and the TOU requirement certainly doesn't help. Data on the quote I have:
- 5.2 kW nominal power, 4.4 kW output from the inverter
- estimated yearly output of 7600 kW.hr
- $40,900, lowered to $28,100 by rebates
- 468 square feet
Last year we used about 12,000 kW.hr, which cost us $2,400. We've instituted a bunch of conservation measures, which should make that figure a lot lower in the future. The critical thing is the summer months, when we'd sometimes been using 1500 kW.hr per month. This is partly the pool pump (which you have to run longer when the water temp is higher), but mainly AC. Actually although we're in Southern California, our house stays pretty cool naturally, and often we go a whole summer without turning on the AC for more than a few days, but there's always the temptation just to turn on the AC because it feels more comfortable. We just signed up for a voluntary program where Edison installs a remote control on your AC and turns it off at peak times, in return for which they give you some money. We've also started using the pool pump for fewer hours per day, which seems to be working OK as long as I'm very careful about all other aspects of pool maintenance.If we hadn't instituted any conservation measures, and if the legislature doesn't backstep on the TOU thing (which seems to have been simply a mistake), then I'm estimating we'd only save about $1,250 per year with the solar system, which isn't much of a return on a $28k investment. Judged purely as an investment, we'd have been better off just putting the money in the bond market or something.
On the other hand, if we do the conservation measures, then the TOU might not be such a big deal, because we wouldn't be buying much energy at the summer, peak rate of $.36/kW.hr. My estimate is that if we hardly ever turn on the AC (which we've done in some summers), then the TOU thing becomes financially irrelevant to us, and the system saves us about $1,500/year, which is somewhat better. It becomes an investment sort of similar to a standard real estate investment, where you pay a bunch of money up front, and then get a steady for a long time. One big issue is that you want to make sure your system lasts long enough so that it pays for itself, and that means you want to have confidence in your warranty. The good news is that the companies I'm getting quotes from have been in business for 40 years. The bad news is that the LA Times is quoting them as saying that unless the legislature reverses the TOU requirement, they'll all go out of business within 100 days.
The real issue is global warming. If it's reasonably neutral in investment terms, then I'm inclined to do it, but it's worrisome to have this cloud of uncertainty.
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The math with current photovoltaics will not come out in favour until the fossil fuel rises by a factor of at least 10 times. Does not matter what, how, who, where. They are simply too expensive to provide a reasonable ROI. They also have a very high environmental cost to produce so people who buy them are not doing a lot of good to the environment.
This is a myth often repeated. I'm going to simply point to a google search that will net many informative results. You'll find numerous calculations which all come to similar conclusions: solar panels have an "energy payback" of a few months to a few years, and their warranties extend well beyond the point where they become a source of income for the owner. This does NOT apply if you cannot place the panels where they will collect sunlight, or a geographic region which does not get enough solar power; there are plenty of online and physical tools to help with the evaluation of both. Solar power is not for everyone, just like hybrids are not for everyone.
There's one big caveat: wattage ratings for most panels are slightly inflated, because they're based off standardized tests using light sources which generate more light energy than you can find here on planet earth. Some manufacturers and retailers are upfront about this; others are not. Size the system off calculations based on your location, not spec sheets.
Photovoltaics are a gimmick, similar to the hybrid cars which allow metrosexuals and hollywood stars to show off some fake green credentials.
As a horsepower lovin' pistonhead, I eye hybrid owners' "my car runs on lolipops and giggles" attitude with some amusement (buying a car that burns gas does not "help reduce our foreign dependency on oil", if you understand that we have to buy oil from many sources for the nation's economic stability, no matter how much of it we use...and that consumer gasoline usage pales in comparison to commercial sector use, namely, petrochemical and truck/train/plane fuel), but hybrids DO most certainly make sense for heavy urban driving, which is exactly what they were designed for in the countries where they hit the public retail market big time: Japan. When Toyota came out with a full-size hybrid (Camry), they've been popping up all over Boston as taxicabs. The two keys are a)heavy usage and b)urban or other stop-and-go driving. Without the heavy usage, the gas savings don't compensate for the additional energy+materials (and hence additional price), and without the stop-and-go driving, hybrids are no more efficient than cars with similar drag-reducing design but regular powertrains.
Hybrids do not make sense for highway cruising commutes, which many people bought them for in the initial craze, mostly because they didn't do their homework. If your drive does not involve a fair amount of speed changes (ie, heavy stop and go traffic), a hybrid car is not for you. Buy a CDI/TDI diesel, or one of the lighter-weight Honda or Toyota econoboxes from 5-10 years ago. Just be aware, Hondas prior to 2000 or so have abysmal crash ratings (I don't know about Toyotas.) Use the money saved to switch over to energy efficient bulbs, install hot water solar collectors on your house, blow in insulation, buy new windows, etc.
Please help metamoderate.
I don't know what is causing the drop-off. However, I do have solar energy system that was installed in 2003. I was not required to install a time of use meter (the E7 tariff in California) but I moved to that tariff because it makes great sense.
The normal baseline rate for electricity on the standard residential tariff (E1) is 11.4 cents/kWh rising to 36.4 cents/kWh for usage over 300% of baseline. On the E7 tariff, during summer peak time (noon to 6pm) the baseline cost is 29.4 cents/kWh rising to 52.8 cents/kWh for over 300% of baseline usage. However, off-peak cost is 8.6 cents/kWh to 32.1 cents/kWh at 300% usage.
What do all these numbers mean? My solar array generates a high percentage of the total amount of electricity generated during peak time. I know this because a data monitor was installed on my solar array and I have detailed numbers on the performance of the panels and inverters. I think it was well worth the $1500 additional cost.
Bottom line: last year I used 16,345 KWh of electricity, 12,096 kWh generated by the solar panels and 4,249 provided by the utility company. However, I ended the year $191 in credit with the utility. This is because they credit me at the current rate when I send electricity back into the grid, and I'm delivering electricity at the time when I get the highest credit, and I'm using electricity at night when the price is lowest. So, last year I received 4,249 kWh of electricity from the utility that I didn't have to pay for. Without the E7 tariff I would have received ~$1,200 less credit for peak time generation and I would have paid ~$160 more for the electricity I did use.
Obviously, mileage will vary for different installations. For me, time of use has been, and continues to be, a great financial benefit. It also contributes to home comfort: I sent my home thermostat to a minimum of 72 degrees and a maximum of 76 degrees, and that's how the thermostat stays 24/7 all year. Extravagant maybe, because I could have saved more electricity with different thermostat settings, but I like my comfort. And saving electricity doesn't do me any good because all it gives me is a larger credit with the utility company (and I can't convert that to cash).
You need to be careful when doing straight calculations like that - the big problem with lead-acid batteries is that their discharge is highly nonlinear. In other words if I have a 32 amp hour, 12-volt battery, if I drain it very slowly (a few amps only), I'll get the equivalent of 32 amp-hours out of it. If I were to draw, say, 32 amps out of it, it would be dead in much less (probably around 35 minutes') time. There are much larger capacities available, but the big problem with this is that A.) The batteries may be affordable, but the control systems are definitely not and B.) the conversion from DC to AC will also kill your storage efficiency. We ran into some of these problems trying to design such a system for a house in a developing community in Ghana.
Quiz: True or False -- On a scale of 1 to 10, what is your middle name?
You're obviously not a Californian. Post Proposition 13, improvements to your house that increase its value don't make your property tax go up. Only the homeowner by voting a special assessment, the local government State Legislature can and only then with a super-majority vote. If you sell the house, however, the next buyer's tax bill will get the full benefit of your improvements. Remodeling the kitchen has the same effect. Which one has a better possibility of lowering your electric bill?
Environmental fuzzy save the birds you're killing from the reflection of your solar panels tax .2%
Does this happen? A quick google seems to indicate that birds have a better chance of getting killed by chasing light on the other side of glass windows than being par-cooked by reflected light. The neighborhood cat kills more birds than the solar panels ever will.
I've got one for my backup server, it cost me like $300 at a boat accessories store. 89 AH and it runs for hours (something like 10 on a fairly power hungry old skool Athlon TBird, or something to the effect - might be a duron, come to think of it). Oh, and watch out for thermal runaway during charging, or you won't have to light a smoke to be toasted.
More Info:
Deep Cycle Battery FAQ
If I mod you up, it doesn't necessarily mean I agree with what you've said, sorry.
The SEGS plants at Kramer Junction in the Mojave Desert have been operating since the 1980's and are the largest solar plants in the world producing 354 MW.
Nevada Solar One is 64MW of solar thermal (3rd largest solar plant) and set to come online this year.
Stirling Energy Systems has a CPUC approved contract with SCE for a 500MW parabolic stirling solar thermal plant.
This document details a lot of the 100 year history of solar thermal attempts.
SHPEGS is our not-for-profit design project to adapt solar thermal to moderate climates by combining it with geothermal and heat pump technology. There is more information and links here.
Because there are economic incentives to use solar paid by the state, via the power company. If you want that $3,000 incentive you have to tell the electric company, but when you do, they jack your rates. Basically the article is showing that the amount the electric company jacks the rates means that, in general, it will remain financially better for most homeowners to stay full time customers of the utility. Now who would have thought they would do that?
"Unheard of means only it's undreamed of yet,
Impossible means not yet done." ~~ Julia Ecklar
Off-peak here is 11 hours per day, so I'd need to sustain something like 1kW (at a guess) 13 hours - let's call it 15 for a bit of slack. No, sod it, let's go for a full 24-hour supply at an average of 1kW (I don't have a lot of heavy electrical appliances that run during the day). So that's 24kW/h - and I suspect I'm guessing high there.
Right, let's consider our power delivery system. Forget 12v, to reduce the current draw I'm going to use 24v electrics. This page has a range of 24v to 240v inverters. They run at around 90% efficiency (inverters are very good these days). Lets assume a full load draw of 50A - that's 1200Ah. LED lighting tends to be easier to get in 12V form, with GX53-type replacements being cheap and easy to get. They put out about the same light as a halogen lamp (maybe a little less) for an input power of less than 2W. At most they're going to pull down maybe 15A for a houseful. Let's for argument's sake say it's 10W, because that gives us a total load on the batteries of 60A. We'll split the lights across the batteries to even the load.
Still with me? Good. We have a total power requirement of 60A at 24v, for 24 hours. This is 1440Ah (it's also 1440kW/h, but that's just co-incidence. 24 volts, 24 hours). Let's go look at batteries.
A quick Google suggests the Elecsol 125 batteries might be the way to go - they're relatively cheap, small enough to be handled by one man (28kg - they're not light!) and not too expensive (a little below the £1/Ah price point). With 125Ah capacity, we'll need 24 to cover our day's requirements.
These are 34x17x24cm, and this is where my crappy arithmetic and geometry fails me. I could arrange them on a special stand about 102x68x80cm, or very roughly the size of a small chest freezer. You'd need a bit more room for the services board, and some switchgear, the inverter and the regulator. You'd still easily fit it in your garage, though.
The power companies told the legislature that they were getting screwed because they had to buy the power from home generators at retail (the same rate(s) they charged the homeowners) and sell the excess at wholesale rates. They got the legislature and PUC to change the rate structure to allow them to charge home generators commercial (time-of-use) rates, which is good for the power companies because most home generators do not generate enough to cover their needs at peak times (especially during the summer cooling season). Of course, since people are not (quite?) as stupid as some make them out to be, the law of unintended consequences kicks in. Homeowners do the math and do not install solar systems and the power companies lose out on all that peak time generating capacity those systems would have freed up, and all the lovely money they could have charged for it. Oh, the joys of artificial economics.
Now, if any of the 3 or 4 "new solar technologies" that promise more conversion efficiency and/or radically lower production and deployment costs (and seen on this board) come to fruition, we will see "solar roofs" all over the place, without the need for artificial incentives.
Look Out Above!
Burning fossil fuels in power plants is an extremely cheap method of power. It can generate power at a cost of ~4cents/kwh.
Only if you completely ignore the environmental impact. Aside from the power plants themselves making most superfund sites look like nice places to take a picnic, what comes out of the smokestacks eventually lands somewhere.
Currently in Northern New England we have a huge mercury problem - Not because we put it there, nor even because our power plants made it (we have one of the highest percentages of hydro and nuclear in the country); Rather, because midwest power plants, with their nice big smoke stacks, end up dumping most of the acids and metals in the smoke on us as rain.
So if you want to include the cost of cleaning up each and every lake in ME/NH, I suspect it would come out a hell of a lot higher than $0.04/KWh.
You're comparing the price of a base civic (manual trans, windows, etc) with a decked out hybrid version, with navigation, sunroof, power everything. Compare apples to apples, a Civic EX and the hybrid version, and you'll come out with a price difference closer to $2k. Using the above math, it'll pay off a little over 2 years. Sounds like good sense to me.
That's because my cat is a god damned ninja. \m/ (-_-) \m/
What you and others seem to miss is that according to the article the California PUC (Public Utilities Commission) has forceably set the rates to all new solar installation at peak rates regardless of the time of day they purchase the electricity to supplement their systems, regardless if it is purchased at night and battery stored or not. This effectively makes it to where anyone with solar that still needs some grid electricity have to pay extremely high rates for that electricity and thus reduces the economic performance of their system. If this was not the case then any peak electricity the customer generated via solar would reduce their peak costs and could make it worthwhile for a customer to slowly add solar as they could afford it however this PUC decision makes it only worthwhile to put in solar if you put in a system that takes you completely off the grid from day one. According to the article, there has been no new solar in California since January 1 "GOOD" or otherwise.
the problem arises when PV pricing starts getting to the point where an enterprising resident can become a power plant and make some money selling peak power electricity. But, the utilities already have roadblocks put in place to help keep those interested in clean energy production down in the noise levels. My guess is that they would rather have brownouts and still make massive profits then to start letting alternative generation systems slowly start taking aways their profits by reducing demand.
Think about it. The energy companies already know that by strategically timing maintenance of critical generation systems, they can reduce supply and boost profits. It was done in 2000 by the electrical generators, mostly in Texas, and currently it looks like the oil industry might be doing the same to help run gasoline prices up.
I've heard a number of people complain about current regulation and utility policies are blocking the increased use of solar PV energy generation so it's not surprising to here any of the TOU issues coming up now. They are looking out for themselves and the PUC seem to be oblivious to any of this.
LoB
"Anyone who stands out in the middle of a road looks like roadkill to me." --Linus
since you do not know howe any of this works and are making things up based on assumptions please let me enlighten you.
Syncing controllers feed power BACK to the system to hel the power companies during peak daytime hours. contrary to your understanding from 8:00am until 5:00pm the most power is being used, having solar back-feed with the RIGHT gear helps the grid greatly reduce loads. These controllers do it very safely and are specified by the power companies. if they dont see voltage from the line side they shut down until they are manually reset.
these systems are proven and in use everywhere. Just because you dont know anythign at all about the subject and jump to some really wild conclusions does not mean the power companies do.
The power companies STOPPED giving solar people the payback at the higher daytime feed rates but giving them the backfeed rates at the cheaper off-peak while they resell that solar power at the higher premium-plus-peak rates. It's a cash grab and nothing more.
Do not look at laser with remaining good eye.
My family recently put in a solar system while constructing our new home, and it's been up and running for about 4 months now. We live on an orchard in California's Central Valley (near Tracy), and we get plenty of sun. The system powers the home and also meets any electrical needs maintaining the orchard may have. Our power is provided by PG&E.
Prior to putting in the system, we estimated our electrical need, and tried to put in a system that would result in not having to pay anything all year. The system ran about $150,000, and the rebate was around $45,000. It's a large array, but we have space so it's kept in a fenced area next to the house, not on the roof. In our previous home electrical bills ran in the $400-$1000 range depending on time of year. Temperatures easily hit 100 degrees for weeks at a time in the summer, last summer we had a few weeks of over 110 degrees. Our electrical need is also high, since we have to get our water from our well using an electric pump, run our air conditioning constantly in the summer (my grandmother lives with us, and is home all day), and we bought some electric appliances.
Since installing the system, we are averaging a credit of $550 a month, which we can carry for up to 12 months. We haven't used the air conditioning, but now the temps are hitting 90, so we'll see how the increase in sun and the increased use of air conditioning balance out. I expect our credit to increase.
For us, the system made perfect sense. The ROI was originally estimated to be about 7 years, and the panels are warranties far beyond that. We purchased electric appliances because we could use them without worrying about driving the bill up. The exception is we have a gas cooktop, which we preferred for cooking. Not everyone has the space to install the amount of panels we did, but neighbors have been stopping by and asking questions, and a few figured out it would be a good investment for them as well. The panels take up about as much space as 3 or 4 of our trees would have, but those trees (almonds) couldn't produce anywhere near the return.
The initial investment was high, but it made financial sense for us, and we had the space to put up a large enough array to meet all our needs. The rebate from PG&E really helped us in our decision, but they benefit every month with the surplus electricity we produce which goes back into the grid. We're considering getting electric utility vehicles for the orchard maintenance, which may also take a larger initial investment, but should be cheaper to run since we can just plug them in instead of filling them with diesel. We're still doing research into how their performance is.