Hi, Technicians~ Thanks to all for the replies regarding "PV behavior when the load is a resistor". My client wants to emulate the "Divert" function as with an old school Bobier NDR-30 charge controller (& also seen with Mr. Katz' Enermaxer controller from days gone by). The 2012 twist is that we've got higher solar wattage, higher array voltage and a wish to use normal 240v heat elements...and no NDR-30 style charge controller with a simple "Divert" connection bolt.
Even once the control & switching is figured out, the other problem is how to get a good percentage of "available wattage" to convert into heat. My takeaway from your astute comments is that MPPT type optimization would still be needed to maximize the power transmission...but the right MPPT optimizer would differ from anything now in production. Since the impedance (resistance) of any heat element would be wrong most of the time, the solar array would be hindered from what it could otherwise deliver. That's the crux of the problem, methinks. My client and I will proceed using no intervening electronics between the array and the heater, under the "some heat is better than no heat" concept. Since this project has no ability to sell excess solar wattage to the grid...but with grid power up and running the home most of the time...we want to reclaim some of the solar array capability as heat. Thanks again for shifting focus to consider the "PV into a resistor" issues. We can now return to our regularly scheduled programming. Jolliness, Mick Abraham, Proprietor www.abrahamsolar.com Voice: 970-731-4675
_______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org
