2 Panels Instead Of 3?

[mohawk]

If I have them at a 45 angle, wouldn't that heat the water better than on the ground? The panels will face south west and will get direct sun most of the day. I was hoping for less panels cuz I still need to buy the solar reel which will run over $300.

[CarlD]

If I have them at a 45 angle, wouldn't that heat the water better than on the ground? The panels will face south west and will get direct sun most of the day. I was hoping for less panels cuz I still need to buy the solar reel which will run over $300.

That depends on how they are exposed. If they are FULLY exposed to the sun, it doesn't matter if they are flat or angled. You only need to angle them if they don't get full sun otherwise. But the ground is your friend: It asks as a giant heat sink and storage device that allows you to continue to use your panels after the sun passes. Besides, a rack costs money as well. You can always add that if you need to.

[chem geek]

If you are at a very northern latitude where the sun is not very directly overhead in the summer, then angling the panel will help. However, the effect is rather small until the sun is quite a ways away from being directly overhead (at noontime). The loss in heating goes as the cosine of the angle difference between the incidence of the sun and the perpendicular of the panel.

For example, if the sun is 20 degrees away from directly overhead, then you get about 94% of what you would get if your panel were angled 20 degrees to "point at" the sun. If the sun is 40 degrees away from directly overhead, then you get about 77%. I'm ignoring any positive effect from ground heating that Carl mentioned and that may more than make up for the loss during the day.

Richard

[mas985]

If you are the computer inclined, here is an application that can help you determine what your average temp is with and without solar. You can specify not only what direction the panels are but also, what type of material they are over (i.e. roof, ground etc.). It takes a bit of time to set up but it is better than a swag.

http://www.canren.gc.ca/tech_appl/in...aId=5&PgID=484

[mohawk]

Thanks for the info. We live in a suburb of Minneapolis and I have no idea what degree the sun would be at noon. I'll ask the husband but he'll probably give me that funny look-like why do you want to know that? Denise

[CarlD]

Thanks for the info. We live in a suburb of Minneapolis and I have no idea what degree the sun would be at noon. I'll ask the husband but he'll probably give me that funny look-like why do you want to know that? Denise

Um, there is no hard and fast answer. It changes every day of the year. Of course, it will be highest at the Summer Solstice, when the sun reaches its maximum latitude of 23 degrees and some minutes (The latitude of the Tropic of Cancer--there, when the sun is at its highest, it is directly overhead--90 degrees). So you have to know your latitude (probably 42 or 43 degrees), so the sun at its highest will probably be about 70 or 71 degrees.

If you really want to be exact, get your lat/long off your GPS if you have one. Then you'll need a Nautical Almanac (though you can find them on-line) to find out at exactly what time, at GMT, the Sun is at its highest "Declination" (latitude). You have to adjust for the time difference and then subtract the Declination from your latitude. Then subtract THAT number from 90 and you'll have the sun's angle at exactly that time.

But if your latitude is 43 degrees, the sun will be about 70 degrees....

[chem geek]

And 70 degrees is 20 degrees away from vertical 90 degrees so the lower efficiency by having a flat panel vs. angled is 94% so isn't that much (i.e. just a 6% loss in efficiency). Like I said, I think this "angling" difference will only be an issue for you if you live way, way north in Canada, but at least now you have the tools to know for sure.

As Carl says, the angle of the sun at noontime depends on the time of year. The main reason to have the panels angled isn't so much for the summer solstice time as it is for the beginning and end of the swim season when you more desperately need and want solar heating of the pool. At such times of the year (spring and fall) the sun is lower in the sky (at noontime). Those that live at the equator don't worry so much about these problems, but I suppose they've got other things to worry about!

Richard