What are some methods of storing unused energy from solar panels.?

Question

What are some methods of storing unused energy from solar panels.?

Answer 1

The Iowa Stored Energy Park is tackling this same problem of excess energy from a wind park.  They have the excess electricity power a compressor that forces air into an  aquifer.  When the air is released, it drives two 134-megawatt turbines, producing enough power for 80,000 homes.  It would work for a solar powered plant also.

Coper Electronics Technologies, EEStor company, and Maxwell Technologies makes ultracapacitors which can store a charge and then disperse it quickly or over time and recharge rapidly with no significant performance degradation.

Lithium ion batteries can store 25 times (per pound) more energy than ultracapacitors.  EEStor company makes a hybrid lithium ion battery/ultracapacitor which they say combines the best of both types of storage device.  Many large capacitors on railroad cars can collect the energy from desert solar plants and then provide power for a locomotive to haul them anywhere in the country (served by a rail line) they are needed.

Answer 2

Storage Batteries is he most common method. You can also use the power to run a water pump that pumps into an elevated reservoir, then falls through a Hydro Generator during the night. Like another answer said, you can use the power to run a air compressor which stores compressed air, then runs an air powered generator. You can also boil water and store high pressure steam, then run a steam turbine-generator.

All of these methods make power very expensive compared to grid power. They are also not very efficient because there are losses every time you change the energy form, but do save on burning fossil fuels.

Answer 3

On a small scale (an individual home or cabin), the most common scheme is not to store the energy.  Excess energy is driven back into the power grid, and the meter runs backwards.  Later, such as at night, when the house uses more than the solar panels are presently making, the meter runs forward.  So from the homeowner's perspective, that's sort of like storing the energy - one gets a credit against future use.

For isolated cabins, and other places without a grid tie, batteries are the typical storage method.  In fact, I've never heard of another method being used by individuals.  The batteries are lead-acid, very much like car batteries, although generally larger.  I've read of a couple people who use NiMH or Lithium, but I think those are just folks who did it because it was cool.  It's certainly several times more expensive.