PV Gap

Kirk Said:

In a solar energy set up with battery energy storage, how many batteries does it take to run a 2200 SF house?

We Answered:

Peter is correct regarding energy use. To get your answer you would need a professional energy audit from a small wind & solar contractor. It's most likely that contractor will recommend significant energy efficiency upgrades for your home as with most homes it's far cheaper to upgrade to high efficiency appliances than it is to install additional energy storage capacity.

Hazel Said:

Why are "Molten Salts" a good solar energy storage media?

We Answered:

http://www.eere.energy.gov/states/altern…

http://www.physics.metu.edu.tr/~ecevit/p…

http://www.nrel.gov/docs/fy99osti/24649.…

http://www.osti.gov/bridge/purl.cover.js…

http://www.sandia.gov/Renewable_Energy/s…

http://home.earthlink.net/~bhoglund/what…

http://www.patentstorm.us/patents/705152…


<edit> Here's another link searching for high temperature industrial/chemical pumping applications. Unfortunately, I think for what you're looking at, you're into stainless steel piping (molten salts will be corrosive) and other expensive equipment.

http://www.google.com/search?q=high+temp…

Clara Said:

where is a site to learn how to make and store solar energy?

We Answered:

Thermal energy storage can refer to a number of technologies that store energy in a thermal reservoir for later reuse. They can be employed to balance energy demand between day time and night time. The thermal reservoir may be maintained at a temperature above (hotter) or below (colder) than that of the ambient environment.

The principal application today is the production of ice or chilled water or eutectic solution at night which is then used to cool environments during the day.

Proposed Thermal energy storage technologies envision the storage of heat, usually from active solar collectors, in an insulated repository for later use in space heating, domestic or process hot water, or to generate electricity.

Molten salt has been proposed as a means to retain a high temperture thermal store for later use in electricity generation. Solar Tres Project Molten salt as an energy store

Most practical active solar heating systems have storage for a few hours to a day's worth of heat collected. There are also a small but growing number of seasonal thermal stores, used to store summer heat for use during winter.

Thermal energy storage is made practical by the large heat of fusion of water. One metric ton of water, just one cubic meter, can store 334 MJ (317 k BTUs, or 26.4 ton-hours). In fact, ice was originally transported from mountains to cities for use as a coolant, and the original definition of a "ton" of cooling capacity (heat flow) was the heat to melt one ton of ice every 24 hours. This is the heat flow one would expect in a 3,000 square foot house in Boston in the summer. This definition has since been replaced by less archaic units: one ton HVAC capacity = 12,000 BTU/hour. Either way, an agreeably small storage facility can hold enough ice to cool a large building for a day or a week, whether that ice is produced by anhydrous ammonia chillers or hauled in by horse-drawn carts.