[RE-wrenches] PV-direct electric water heating

[Luke Christy]

Hi Wrenches,
Now that the cost of modules has come down so much, has anyone out there experimented with solar electric water heating? As in: direct connecting a short series string of PV modules to a tank -style electric water heater with an element of an appropriate voltage and wattage rating…?
 
A off-grid customer of mine who is also an electrical engineer has a situation that seems ideal for trying this idea out: he has a gas-fired tankless water heater and a water source that is very cold year-round. The idea is to take a 30 or 40 gal electric tank heater, switch out one of the the 240V elements to something like a 96VDC, 1000W element (difficult to find, but available), and direct connect 3 or 4 60-cell modules in series (with a disconnect and high-limit control of course). The tank would then serve to preheat the cold feed to the tankless heater. We think we can get a decent daily temperature rise with this setup. Probably not enough to heat the tank to a normal DHW temperature, but certainly enough to offset a good deal of propane consumption, and all for what I predict will be considerably less cost than a small solar thermal system.

Has anyone tried this? I'd appreciate any insights or opinions.


Thanks
-Luke Christy

NABCEP Certified PV Installation Professional™: Certification #031409-25 
NABCEP Certified Solar Heating Installer™: Certification #ST032611-03       
CoSEIA Certified PV Installer 

Solar Gain Services, LLC
PO Box 531
Monte Vista, CO. 81144
SGSRenewables at Gmail.com
719.588.3044
www.sgsrenewables.com

   







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