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."

Comments

Re:Batteries

[Firethorn]

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.

Alternative power storage

[simm1701]

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!!

solar and hybrid myths

[SuperBanana]

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.

Re:About Edison's Dirty Little Secret

[Locutus]

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