PV powered circulator pump for AET solar hot water system undersized PV panel

Posted by on January 10, 2008, 02:42:18 PM

PV powered circulator pump for AET solar hot water system undersized PV panel
Any folks have experience with the March pumps supplied with the AET hot water system kits? My system was supplied with a 12 volt 20 watt sunwise panel and a 12 volt March pump. The panel was substantially undersized for installation in northern NH and would only run the pump uncoupled for about an hour on a sunny day (in December). My short term solution was to install a spare 12 volt Siemens 48 watt panel. The system is running well now but the concern is "am I going to cook the pump" later in the year when there is more sun? Guy Marsden mentioned a similar problem in his Home Power articles about an install along the Maine coast and he doubled up on his panels.
 

Posted by James Cormican on January 10, 2008, 02:55:04 PM

Re: PV powered circulator pump for AET solar hot water system undersized PV pane (Reply #1)
probably wont cook the pump, but has potential to cool already heated watter off.  by increasing pv size, you increase the likelyhood that the pump runs before the collector is hot enough to heat the water that is already warm in the house in its tank.  trial and error it, 48w is not obscene, and will likely be fine.  with pv direct to pump, you have no control over high limit, so you may or may not want to switch back in summer based on your results.  make sure t & p valve in tank is good before summer when overheating may be more likely.

others in the community may have more experiece with this, especially mr. mayrand.  i'd bet we see some more answers soon.

james
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Posted by John B on January 10, 2008, 04:51:49 PM

Re: PV powered circulator pump for AET solar hot water system undersized PV pane (Reply #2)
Quote from: James Cormican on January 10, 2008, 02:55:04 PM
probably wont cook the pump, but has potential to cool already heated watter off.  by increasing pv size, you increase the likelyhood that the pump runs before the collector is hot enough to heat the water that is already warm in the house in its tank. 

I use an El Cid 5w pump in my system that I tested by putting it on a 12V car battery. The only thing that it did was pump a whole lot faster that what it does on the 5W solar panel. I suspect the March pump is the same and will not draw any more current than it can handle, provided the PV panel is still a nominal 12V.

Early startup should not be a problem if he has a temperature differential switch controlling the pump, which I suspect he would. My setup is very simple (no freeze to worry about) and it pumps as soon as the sun comes up and continues pumping until the sun goes down. I'm considering purchasing one of those temperature differential switches myself now that the temperatures have been dropping down to the low 70's at night. lol.
 

Posted by James Cormican on January 10, 2008, 05:36:16 PM

Re: PV powered circulator pump for AET solar hot water system undersized PV pane (Reply #3)
i dont think he has a dtt, because the pump is controlled solely by the pv module, no?

james
Alt-E staff
AltE
"Making Renewable Do-able"
http://www.altEstore.com/

Tel: 877.878.4060 x107  or +1.978.562.5858 x107
Fax: 877.242.6718  or +1.978.562.5854
 

Posted by John B on January 10, 2008, 09:08:53 PM

Re: PV powered circulator pump for AET solar hot water system undersized PV panel (Reply #4)
I think the AET systems come with them standard.
 
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