I have a simple off grid system - two 450w panels, SCC, inverter, AGM batteries and controls. It runs pool pump - so far so good. The setup is as follows:
1. Timer turns system on, it starts in battery mode.
2. If there it enough sun, pump runs all day on solar.
3. If cloudy and solar panels do not generate enough juice, system switches to grid after battery voltage drops to 24v.
4. Runs on grid power until battery is recharged, then switches back to solar and cycles repeats.
I'd like to run the pump on solar only when there is enough sun, and on grid on cloudy days without cycling the battery, saving it for blackouts.
For that I'm looking for a device ( reasonably priced) to use as a solar radiation meter. I'd like to switch system to solar on a signal from a device only when there is enough sun power to run the pump, without draining the battery. For now I'm using a tiny panel from garden solar light, loaded with 300ohm resistor. It does generate voltage across the resistor from 1.5 ( cloudy) to 2.8 ( full sun). I use this signal for control. But signal does not look stable. One day shows 2.75v, next day 2.65 at visually same sun conditions. Tried different size resistors, does not make a difference in stability ( voltage of course does change a little) Does anybody know such a device- in $20-$50 range? Getting an industrial grade pyrometer is not an option.
Should be a device with voltage, current or relay output, not a hand-held meter with a display for field measurements.
1. Timer turns system on, it starts in battery mode.
2. If there it enough sun, pump runs all day on solar.
3. If cloudy and solar panels do not generate enough juice, system switches to grid after battery voltage drops to 24v.
4. Runs on grid power until battery is recharged, then switches back to solar and cycles repeats.
I'd like to run the pump on solar only when there is enough sun, and on grid on cloudy days without cycling the battery, saving it for blackouts.
For that I'm looking for a device ( reasonably priced) to use as a solar radiation meter. I'd like to switch system to solar on a signal from a device only when there is enough sun power to run the pump, without draining the battery. For now I'm using a tiny panel from garden solar light, loaded with 300ohm resistor. It does generate voltage across the resistor from 1.5 ( cloudy) to 2.8 ( full sun). I use this signal for control. But signal does not look stable. One day shows 2.75v, next day 2.65 at visually same sun conditions. Tried different size resistors, does not make a difference in stability ( voltage of course does change a little) Does anybody know such a device- in $20-$50 range? Getting an industrial grade pyrometer is not an option.
Should be a device with voltage, current or relay output, not a hand-held meter with a display for field measurements.
Last edited: