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Grumman solar panels?

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Larry Weingarten
Larry Weingarten Member Posts: 3,877
in THE MAIN WALL
...panels were installed in a drainback configuration in my area (central California). If your panels had tap water or glycol run through them, I'd worry about scaling or pitting. Look at the tubes and headers to see if there is any bulging. That would suggest freeze damage. If they were installed, drainback, using clean water, they are probably like new ;~)

Yours, Larry

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  • Eric Johnson_3
    Eric Johnson_3 Member Posts: 38
    Grumman solar panels

    Anybody know anything about Grumman hot water solar panels? There's a used pair (probably 10 years old or older) for sale, and I'm wondering if trying to get them would be worth the trouble. They're asking $500 for the pair, including the control panel (whatever that is), as is, where is (the roof).

    Beyond that, is there anything special to look for in used solar panels in terms of red flags?
  • Eric Johnson_3
    Eric Johnson_3 Member Posts: 38


    Albany, NY, so I'm sure it's a closed-loop, glycol arrangement. The lady said something about hard water destroying the tank, so that's two bummers out of two.
  • Robert O'Brien
    Robert O'Brien Member Posts: 3,573


    More like 20 years old

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  • Ron Huber
    Ron Huber Member Posts: 121
    20+

    They stopped manufacturing in 85, honored the 5 year warranty. The control panel is a wall mounted double wall heat exchanger and two circulators, differential controler, expansion tank, relief valve all enclosed in a hard shell cover with temp gauges and switch. The water side circulator is to draw and return domestic hot water from a conventional water heater while the cast iron one is the solar loop, we could use ethelyne glycol which is more stable at higher temps becuase of the double wall heat exchanger
  • Eric Johnson_3
    Eric Johnson_3 Member Posts: 38
    A lot of hardware

    That sounds like a lot of hardware for $500. Are those components (circs., exp. tank, etc.) replaceable with off-the-shelf parts, or is it pretty much a proprietary nightmare?
  • Ron Huber
    Ron Huber Member Posts: 121
    parts

    circulators were Grundfos 15/42 equievelant, water side was a bronze Grundfos, both are union flanges, basic solar controller, the only thing that you may not have to replace would be the panels, unless they stagnated with old glycol for years. Maybe look into buying new panels. With the 30% tax credit you may be better off with a new system.
  • Eric Johnson_3
    Eric Johnson_3 Member Posts: 38
    Thanks

    Thanks for all your input. I'm in NYS, so it's a combined tax credit in excess of 50%. That looks to me like the way to go. Is there a consensus on whether evacuated tubes are worth the premium? I heat my hot water with wood during the heating season, but it would be nice to cut the elecric bill in the spring, summer and fall.
  • Paul Pollets
    Paul Pollets Member Posts: 3,669
    Vacuum tubes

    the vacuum tubes will output 70% more than flat plate collectors, most do not require the drainback scenario as the collector header has the ability to prevent overheating and the controls can do frost protection. The flat plate collectors are better suited south of the Mason Dixon. The technology has changed dramatically over the past 20 years. I'd suggest taking the Viessmann solar course if you want to know state of the art solar, or spend some time on the Thermomax website.

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