PV Gap

Billie Said:

which solar panels for heating water and producing electricity would you recommend?

We Answered:

Solar panels only warm the water. They do not make hot water. You still have to use a boiler or immersion heater to make it hot enough for bathing. They do save on gas or electric though, but you will not feel any financial benefit for about 5 years taking into account the cost of purchase and installation.

Allison Said:

Which is more efficient: electric or solar heating?

We Answered:

Don't confuse "green" or cost with engineering efficiency. The efficiency should be calculated as the amount of energy converted into temperature increase of the air or the water (total mass of, say, water times the specific heat of the water time the delta T) divided by the amount of heat put in. If your experiment uses the same mass of water for the solar heater and for electric heater, then heat gained is directly proportional to the delta T (higher delta T = higher efficiency). Then the hard part is figuring out how much heat was put in. With the electric heater, this is straight forward, just calculate Kw-hours or joules. For the solar heating, it is a little more difficult to measure how much heat went in. I would guess that Electric could be more efficient because, with a good design, virtually all the electric power could be converted directly into heating water (with some heat going into the container and some going into radiation heat loss). With solar, there may be more heat going into the container and maybe more radiant heat loss. On the "green" side, the sunlight is free.

hope this helps

Vanessa Said:

solar panels?

We Answered:

You can make your own. Materials are cheap and readily available. One caution. the sun's heat in a flat panel can raise temperatures high enough to cause deterioration of wood, so significant that if dry and used for a few years, they can set fire to the wood. They need to be mounted on stands that lose heat before contact with wood or asphalt shingles.

Systems of water heating panels have to be protected from freezing or drained. They can be filled with antifreeze, but then we have to be very careful to avoid mixing with domestic water.
Systems have to be designed to deliver heat, and avoid dissipating that heat by circulating when there is no sunlight, or when panel heat is less than that in storage.

We can have a refrigeration line going across the top of banks of flat panel collectors, such that the refrigerator sealed unit removes heat from the panel to deliver it to either a water storage or to inside air. This means we have no freezing problem, no antifreeze to poison us.

But people who have learned how to make reliable flat panel collectors like to make some money. The information is readily available for anyone able to read and understand, with none of that mark up.

Ron Said:

Solar panels for heating water?

We Answered:

I quite like these ones http://www.scan.co.uk/Products/ProductIn…

Cory Said:

I have very poor circulation through my solar panel heating system.?

We Answered:

Sounds like the pump has gone, it may make a noise, this doesn't necessarily mean it is working, if the heat has stopped up to a certain point, then it is probably the pump.