[amsat-bb] Re: Solar Power (I was wrong)

Greg D. ko6th_greg at hotmail.com
Thu Oct 1 21:13:20 PDT 2009

I've always wondered why the solar panel makers don't put water tubing on the back side of the panels.  Boost the efficiency, and get hot water for the house or pool at the same time.  Seems like a no-brainer.  {shrug}

Unfortunately for me, I have large trees shading the house (big enough that I'm hoping I'm coming out ahead with lower air conditioning bills), and a roof angle exposure that is not solar-friendly even if they weren't there.  So I was thinking, if I had space for just a few panels, perhaps I could go low-tech with a system built from a scrap UPS.  After all, I've got an APRS station - PC, TNC, radio, and internet connection - using power constantly, and I often find perfectly good UPSs being tossed out (i.e. free) because the battery is shot and not worth replacing.

Put the solar cells in place of the UPS' battery, and modify the power failure detect circuitry to work backwards - give preference to the battery/solar side, only switching to the line side if there is insufficient "battery" power.  This will give me free 120 vac whenever the sun shines.  At night, it would power-fail back over to the line, and only then would the power company's meter start to spin.  I'd probably put a regular UPS down stream from the hacked-up one, in case the failover/back from line to solar wasn't real clean.

The biggest problem I see is that most of the solar panels available these days are in the 50-60 volt range, which means that you'd need to do a conversion down to battery voltage first.  (Maybe put two panels in series and run them into a regular 12v DC power supply?)  

Now, I just need to find a source of free-to-cheap solar panels.  I almost bought a set at a local Ham swap ($10 ea) that had cracked surface glass but were otherwise functional, but I didn't think they'd survive the trip home in my car (no place big enough to lay them flat).  (I'd need to weatherproof them too....)

Anyway, just a thought...

Greg  KO6TH

> Date: Thu, 1 Oct 2009 18:46:28 -0700
> From: ptrowe at yahoo.com
> To: bruninga at usna.edu; amsat-bb at amsat.org; wb3jfs at cox.net
> Subject: [amsat-bb] Re: Solar Power (I was wrong)

> One of my friends installed a water spray system to cool the panels since
> they lose efficiency fast as the temperature goes up. Also, it doesn't
> take much dust or bird poop to cut the efficiency. So if you install a
> system, be prepared to get on the roof every month or so to clean the
> panels.
> Regards,
> Pete
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