PV Gap

Nora Said:

Motherboard for building an inexpensive solar powered computer?

We Answered:

well the mother board doesn't use much power at all but it depends on what kind of cpu you wan't, i know you said something about it but it all depends try www.tigerdirect.com

Kurt Said:

How do I make a solar panel?

We Answered:

What you could do is just place mirrors in such a way that the sun's rays focus on the water heater. They actually do this on top of homes in the southwestern U.S. The water tank is stored horizontally on the roof, and reflective surfaces direct sunlight to heat the water heater.

Louise Said:

solar power pumps, a question of what works best?

We Answered:

I'm a thermodynamics engineer, not a horticulturalist, and I'm wondering about the practicality and purpose of your plans.

A solar panel designed to provide hot water, or other hot fluid, will provide no more than 1 kW of heating capacity per square metre of panel, in clear sunlight.
The greenhouse itself will have pretty much the same heating effect in sunlight, so the only purpose of the Solar Panels would be to provide night time heating and that requires heat storage capacity. If you put in 10 sq m of solar panel (say 10ft by 12ft) you could heat a water flow rate of about 4 l/min (say 1 gallon/min) about 35 deg C (60 deg F). Over 6 hours of daytime sunlight this would give you 1.5 cu m (360 gallons) of warm water which may be sufficient to keep frost off a small greenhouse. If you live somewhere the temperature drops way below zero, or if you have a large greenhouse you'll need a lot more solar panel and storage capacity.

You don't need to worry about high temperatures in your system, unless you are going to leave the system non-operational for long periods of time, and even then you should be able to design it to avoid overheating.

You may find a better way to solve the heating problem is to insulate the greenhouse from cold night temperatures and put lots of large rocks and things inside the greenhouse which will store the daytime heat and release it at night.