How to Use this Web Log

1. Browse through articles by clicking on "Older Posts" below each article in the center column.
2. Search through the Blog Archive at the lower right-hand column.

3. Read Editor's articles to the right.
4. Get Technical help in the lower left hand column.
5. Efficiency and low-waste strategies in the lower right column.

Wednesday, May 7, 2008

Cheap Energy Storage is Here Now

In answer to a question from William Hughes-Games from New Zealand
Hi William,
You wrote:
I'm not sure how one can only buy from the power company as a back up when home generation is low. No problem if you have your own batteries but the common (possibly incorrect) wisdom is that batteries are an economic no-no.
Actually, I would say that the conventional wisdom is wrong. This is why. The economic choice in batteries is flooded lead acid at this point. (However that may soon change.) By my calculations these batteries cost approximately $US 0.15 per stored kilowatt hour. (also by my calculations, the new Altairnano batteries will cost only $0.03 per stored kwHr but they will seem expensive because with 15,000 deep cycles, you buy a lot of storage in advance).
But, that is a lot, you might say. What is not recognized by those who have not lived with these systems is that only a fraction of the energy you use needs to be stored as electricity. So while you may need to store enough to meet your nightly use for a few days, most of your energy is or can be scheduled to be used during the day, directly from panel to inverter. This greatly reduces the amount of storage required. And by the way you don't have to disconnect the batteries to do this. The AC inverter will have first call on the generated energy - only what's left over goes to the battery.
For instance the largest energy user in my system is my refrigerator. I run it a bit cooler than I would otherwise and then it turns off with a timer during the night after the normal use period. This way, energy is being stored as cold. In an efficient modern appliance, little cold is lost when no one is opening the refrigerator.
I try whenever possible to run my washer and dryer during days with bright sunlight. This way I am storing energy as clean clothes. The same can be said for food processing, and other energy intensive activities. In the end, electricity is useful because of the function that it allows. If you maximize your energy-use timing, you get the same function at the at a much lower cost because then the kwHrs are not stored.
This is why there is a lot of room for smart energy use systems. With a system in which instrumentation can activate on-off timers or switches, you can even do some chores like laundry while you are away, to optimize energy-use timing.
So, say you might use an average of 5kwHr/day. By maximizing energy use timing, you may only need to store 1-2 kwHr. So total cost of your battery storage is much lower on an averaged kwHr basis. From my experience it is not an issue, especially for retired persons with flexible time.
This also means that all the energy you produce is tax free except for the tax on the original equipment purchse. Over a 20 year estimated system life, this can be a huge saving.
At any rate, with batteries you can still be grid inter-tied if you choose to. It actually makes more sense to only sell to the power company in the summer when you are likely to have a surplus. If your average stored energy cost is $0.05/kwHr used and your generation cost is $0.08/kwHr, the total of $0.13/kwHr is not bad, especially if you sell your surplus in the summer, to defray these already low costs. And what value can you place on a green conscience, knowing that your energy footprint is not destroying the environment?

PS. Also noteworthy is that by buying your system now, you are locking in rates for years to come.

Thursday, May 1, 2008

Distributed Solar For The Masses

Solar Facts
Jonathan Cole

The simple fact is that our society cannot sustain the wasteful energy practices developed in the era of cheap oil. If we combine a dramatic refocusing on efficient, non-wasteful, energy use with renewable energy installations we can have our cake and eat it too. In the end, regardless of the mix of centralized and distributed generation, the large companies will end up being the suppliers in most cases, that is if they are smart. The dumb one's will join the buggy whip manufacturers in business history.

I can state unequivocally from personal experience of 25 years of using solar energy that we can live very comfortably and very affordably if we combine, efficient appliances, non-wasteful practice and distributed solar backed up by the grid.

I am amazed at the installations I see with 10kw and more of PV for a 4 person household. I live in a cloudy area and run 1200 peak PV watts to power my complete assortment of modern appliances. I use propane for cooking and instant hot water (soon to be pre-heated with solar) and otherwise everything is electric. Computers, scanner/printer/fax, large flat-screen TVs, DVD/VCR players, washer and dryer, refrigerator, lighting, cordless phones, stereo system, table saw and all power tools, microwave oven, and more. This is with occasional backup in prolonged dark cloudy weather. All the solar energy and balance-of-system equipment cost less that $12,000 including my $2600 backup generator. I average about 6 hours per month of generator use. which costs me about $30. I have no other electric bill. By the way I bought nearly all of this equipment on Ebay!

Efficiency, no-waste practices, energy use monitors and distributed solar add up to a winning combination. Of course this is not for city dwellers, but that leaves a lot of room for distributed PV.