Hi, I'm wondering what are some resources available for the testing as a user for diy QC of good / bad panels vs. their specifications? (0-22V / 0-6A / 100W).
I just want to see if the panels I am getting are working correctly and meeting their general rough expected performance and are free of functional defects.
Ultimately I'm planning to be using a very small low voltage DC system just to run equipment and charge low voltage DC battery backup reserve either 12 / 24 / 48V battery and 12-22V coming in from the 100W panel(s).
I also want to obviously be able to use the power so if there are good reliable cheap basic equipment suggestions for a LV DC DC-DC MPPT controller / charger I guess I could get / use that as a rough indication maybe vs. test setup equipment.
Basically I'd be looking for achieving / quantifying the approximate maximum power & {V, I} delivered under light conditions that are as maximal as possible within the next week or so. Testing could be a fully manual process with a standalone voltmeter / ammeter / luxmeter / resistive load or if there's some automated system for doing it that'd be fine too.
I haven't gotten any DCDC converters / inverter / battery charger equipment as a load so I don't have any such thing to hook the panel under test to to see if it is producing NNN W power in that way. I wasn't thinking of buying such off the shelf but I guess if there's some good quality / really inexpensive & readily available MPPT DC-DC battery charger unit or something which also measures / reports power I could get / use that vs. improvising / acquiring test setup equipment?
It seems like I'd potentially be able to use:
* Calibrated lux sensor of some kind to measure the sunlight intensity at the panel during a test; (I don't recall what standard wavelength vs. sensitivity curve might be needed). Or maybe there's a "local" weather station or something in the area that would report "close enough" values given known latitude / longitude / time of day so the only variable would be local micro climate clouds / haze and ideally I'd test when "pretty clear". Suggestions for DIY or COTS inexpensive but useful units? I don't happen to have any just-freezing platinum cube handy for a SI blackbody source.
* Fixed load resistance approximating the MPP full power load given the panel stated max. power V&I specifications, or better: Adjustable load resistance capable of dissipating or sinking variable amounts of power at 23V-0V 7A-0A (~100 W for a small panel). Load level could be possibly manually or automatically adjusted to achieve rough MPP maximum power point operation for a given moment.
* DMM Ammeter for measuring current unless integrated into the tester apparatus.
* DMM Volt meter for measuring the loaded and unloaded voltage unless integrated into the tester apparatus.
* Measurement of time, longitude, latitude coordinates, and temperature sensor for approximate panel surface temperature during test.
So obviously I can cobble these kinds of things together given time from individual parts, but I'm wondering what resources / parts sources / equipment could facilitate this testing?
In particular I have no calibrated photometer / lux meter or optical source, though I have various photodiodes and small area test solar cells, LEDs, and such I could hook up if there's a means of rough calibration.
Secondarily I don't know what good / cheap 12-24V / 100W rated load resistors are available as parts or whether some quick hack with incandescent bulbs, nichrome wire, heating elements, electrodes in a saline bucket, or whatever is the most viable quick and dirty solution for this. I'm guessing nichrome wire and a sliding jumper might be a easy manual option if nobody has made a variable power DC-DC SMPS power sink or something cheap.
Ideas / suggestions?