[RE-wrenches] PV into a resistor: please advise

[Mick Abraham]

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
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