[renic]

Originally Posted by ToddF

First, I would separate solar electric from solar thermal.

...

As far as a downside, copper used in the absorber plates and pipes is through the roof. But its kind of like oil: a doubling of oil prices only marginally raises the price of gas since the raw material is only one expense. Manufacture and distribution of solar panels does not rise as quickly as the copper, thank god.

Another downside to solar thermal is that, for domestic uses, you need to use the heat energy when it is available, or before it goes away. I.E. a homeowner who installs solar water heating wouldn't get much benefit if he takes his shower every day at midnight (unless the storage tank was extremely well insulated).


Larger applications, like solar towers can get around this by heating molten salt instead of water (http://thefraserdomain.typepad.com/e..._solar_to.html)

[solarhomes]

As far as wind energy is concerned, this company is developing a novel idea for chasing the wind down at sea and storing the energy as hydrogen gas.

About the WINDHUNTER Hydrogen Generation System

[ToddF]

Back to solar thermal, my 200 gallon solar storage tank gets up to 170 degrees this time of year and stays above 120 for two days of clouds (even when we're using hot water normally). Solar heat is usually not sized for 100% of your use. You need a backup. That could be considered a downside. But tanks do not cool down that quickly. Even when insulation is so-so.

Heat storage for homes is on a different scale if done right. Houses built on 2 foot sand beds have 100 times more storage than my 200 gallon tank and do well in the MN climate. Its tough to size the solar to the sand bed, though, but "good fits" provide 90% of your heating if you're willing to live with 60 degrees during a cold snap.

[renic]

Originally Posted by ToddF

Back to solar thermal, my 200 gallon solar storage tank gets up to 170 degrees this time of year and stays above 120 for two days of clouds (even when we're using hot water normally).

Wow. what are the details on your system?

[ToddF]

I bought 120 square feet of used collectors that heated a workshop in Iowa for thirty years.

Design Tanks from South Dakota makes a sectional fiberglass tank. They get through a 30 inch door and can be up to 450 gallons. I insulated the tank with layers of foil-faced bubble wrap with air spaces. We have a closed-loop antifreeze system that uses a PV circulating pump.

This summer, we rarely used natural gas to heat domestic water. The back-up water heater drew water from the solar storage tank that was 10-20 degrees hotter than its 120 degree setting.

Now that the heating season is beginning in Lake Wobegon, we will use some of the solar to warm the floors of our house. The tank will not get to 170 until the spring, but any amount of preheating we can do for our water heater saves natural gas and carbon dioxide.

[mollyL]

I know several people who use both wind and solar power; in the summer they do solar, and when the season changes they begin to use wind power. Everybody seems very pleased with their two-fer power arrays.

[justontime]

Originally Posted by mollyL

I know several people who use both wind and solar power; in the summer they do solar, and when the season changes they begin to use wind power. Everybody seems very pleased with their two-fer power arrays.

How much space is required for this? Would it be possible to do this in a small house in a crowded street?

[mollyL]

The majority of the solar panels are on the roof; one of my friends have an array of panels also in the back yard which was kind of a small yard. The other folk also have the array on their roof as well, but I don't know if there were anymore in the back yard; I didn't see if they did or not. These houses were what I would call a middle size to a little larger than normal house without a lot of yard space. I hope that helps; I'm not that great on dimensions.