Solar Hot Water Question

fbartels

I've been looking into solar hot water panels, both for heating water and as a partial solution to home heating. In order to use solar for home heating many more panels are needed than the typical 2 or 3 used for water heating. In the warm months of the year these extra panels would be generating a lot of heated water. Here is my question. Has anyone run across interesting ways to harvest all the extra energy collected over the summer (besides everyone in the family taking really long showers)?

watkins

Dear Fred,

You might find these sites useful:

http://www.azsolarcenter.com/technology/pas-1.html

http://www.homepower.com/article/?file=HP114_pg10_AskTheExperts_4

Short term storage can be increased by burying an insulated water tank in your back garden and heating the water in that, giving you hot water during the night and on cloudy days. Very long term storage is another matter.

Regards,
Bob

tim

@unknownuser said:

Has anyone run across interesting ways to harvest all the extra energy collected over the summer (besides everyone in the family taking really long showers)?

Sure;
a) build a swimming pool
b) heat it with that hot water
c) invite many hot babes round to use pool
d) enjoy

fbartels

Bob, thanks for the links. Tim, thanks for the humor.

I asked the question to the tech folks at Radiantec and they replied with the following. I think if you could somehow use the surplus summer heat to generate electricity you would have a really sweet solution.

@unknownuser said:

Thank you for your recent visit to our website. We design the system so that the panels are mounted at an angle that most effectively captures the winter sun that passes lower on the horizon. During the spring, winter and fall we utilize a high temperature override control. When the system temperature gets too high this control will turn on one of the radiant pumps and circulate water through a zone even if the thermostat for that zone is satisfied. With this detail we are storing the extra heat within the envelope of the home.

During the summer when the sun passes over higher in the sky the panels are not making as much heat. We hope that much of your domestic hot water can be heated by solar during this time. If the system temperatures get too high and no domestic hot water is being consumed than another type of safety control is used. This control is referred to as a Heat Dump Valve. The Heat Dump Valve is attached to the domestic hot water line and when activated by a high temperature reading it allows some hot water to be drained from the system. This action allows fresh cold water to flow into the system cooling it enough to allow the panels to once again begin working.

A newer feature that Radiantec has designed for prevention of over heating during times when extra heat is not desired in the home is referred to as “Garden Root Zone Heating”. All though this is a manual valve operation it is a great way to rid the system of excess temperatures. The idea is to bury tubing under a garden area. A valve can be opened to allow heated solar fluid to circulate through the garden zone which could very well extend your heating system in the later fall months.

pbacot

@unknownuser said:

A valve can be opened to allow heated solar fluid to circulate through the garden zone which could very well extend your heating system in the later fall months.

Do you think they mean "extend your growing season"?

My understanding is that the solar angle is crucial for max. efficiency of these systems and, by their nature, they would be difficult to make tracking or adjustable, as photovoltaic panels sometimes are.

You may be onto an idea. Maybe someone with some background in refrigeration can explain how a refrigerator runs on a gas flame (not me!), but that's an example of heat being made to do something else. An engineer could tell you if there is enough thermal energy of the right sort to make any such an effort worthwhile.

jim smith

Here is a link to a Wikipedia article on absorption refrigeration, rather than compression refrigeration. They do mention one possible heat source as "solar" in the article. I have seen some propane operated absorption refrigerators that have a backup electrical resistance heater to pick up the slack if the propane runs out before a tank recharge. However, I have not seen a production model solar fridge.

http://en.wikipedia.org/wiki/Absorption_refrigerator