Which Solar System Is More Efficient?????

[erichtopp]

Well I am getting closer everyday to getting a hot water solar system sorted out for my home with all the help I've been receiving here at the Otherpower.com  There just isn't another site out there with so much good information. Can any of you tell me which solar collector is more efficient at converting the suns rays to BTU's of energy per square foot of solar collector???

1) Using a hot water solar collector

OR

2) A photovoltaic solar collector with an electric heating element attached

My second question is, which type of transparent cover is best for a hot water solar collector regardless of price??? Which one let's the suns rays through most efficiently???

1. Lexan
   
2. Acrylic
   
3. Glass ( if glass what kind of glass is best??? )
   
4. Other type of covering over the hot water copper collector tubes
   
   

Thank you in advance for your help on this one. Rgds, Erich

[PaulJ]

   Option 1) is vastly more efficient and much cheaper. Heating water electrically usually only makes financial sense with cheap (off peak) grid power.

   My commercially made solar HWS uses tempered glass (about 4mm thick) to cover the collectors.

   Paul.

[pyrocasto]

I would say deffinantly solar water heater. With pvs to heating element you may come out with 10% efficiency, though with heating panels you may a good 30% or so. Depends on how you build it.

As for a cover material, I would have to say glass. A low iron glass, which is the same they use in solar PV panels, will stop less light than regular glass. Will not yellow and cloud like plexi types will.

[GaryGary]

Hi,

In rough numbers:

PV panels have about one fifth the efficency of solar heating panels (about 10% for PV vs about 50% for solar heating panels).

And, PV panels cost roughly 5 times more per square foot.  

So, with solar thermal panels you get about five times the energy at about one fifth the cost.  A pretty good deal!  Its always been a puzzle to me why PV gets so much more attention than solar heating when solar heating is so much more cost effective?

If you are a DIYer, you can do even better, since you the solar thermal panels are simple and can be built with common hardware store materials at a low cost.

Gary

[dinges]

The Milky Way, of course!

(sorry, couldn't resist...)

Peter.