Casper042
New Member
I bought a cheap MPPT from Amazon:
This is to help smooth out the power for a Solar Powered Pool heater.
I use a 12v DC Sump Pump and some Black Drip Line Tubing from my local Hardware store.
Originally I had used a DC Cutoff circuit that would cut the power when the voltage dropped too low, and then turn it back on when it came back up.
I figured the solar panel would trigger this nicely.
Unfortunately with only that and a Buck Boost in between the PV Panel and the DC Pump, when the DC Pump started it would cause the PV voltage to drop well below the cutoff point and the cutoff circuit would kill the downstream power.
Then the panel voltage would jump back up and the cutoff would turn the output back on.
This dance would happen hundreds of times each morning from what I could tell and eventually killed the pump.
I copied a YouTube design I saw and then just oversized the PV Panel to get more buffer. Guess I got what I "paid for"
Anyway, this year I added the cheap MPPT above and a 12v 5Ah UPS Battery and it works MUCH better.
But the problem is the MPPT doesn't have a Daytime mode.
It's optimized for 24h or Night time operation, more useful for lights or something like that.
I am looking for a way to put this MPPT (or buy a cheap replacement) into a mode where it waits till Dawn + 3 hours and then turns on the load.
By then the sun will be starting to warm up the black tubing enough to be worth it.
Then have it cut off the power at Dusk (or even a bit before).
Ultimately it makes no sense to run the pump through the tubing unless there is enough sunshine basically.
And I fear I am going to kill the batter by running it down to the 10.7v cutoff voltage and then back up to 13v during mid day, every day.
I really just need the battery to handle the "cold crank" if you will of the DC Pump.
After about 60 seconds the black tubing is fully flooded and the pump wattage drops considerably.
My other idea would be to just add a ESP32 or similar with a Relay, and write some simple code to only allow the load to kick in during the times I want.
The ESP32 could be powered by the USB port on the MPPT above.
The Relay would be between the MPPT and the DC Pump.
Amazon.com : 20A Solar Charge Controller Solar Panel Battery Intelligent Regulator with Dual USB Port 12V/24V PWM Auto Paremeter Adjustable LCD Display : Garden & Outdoor
Amazon.com : 20A Solar Charge Controller Solar Panel Battery Intelligent Regulator with Dual USB Port 12V/24V PWM Auto Paremeter Adjustable LCD Display : Garden & Outdoor
www.amazon.com
This is to help smooth out the power for a Solar Powered Pool heater.
I use a 12v DC Sump Pump and some Black Drip Line Tubing from my local Hardware store.
Originally I had used a DC Cutoff circuit that would cut the power when the voltage dropped too low, and then turn it back on when it came back up.
I figured the solar panel would trigger this nicely.
Unfortunately with only that and a Buck Boost in between the PV Panel and the DC Pump, when the DC Pump started it would cause the PV voltage to drop well below the cutoff point and the cutoff circuit would kill the downstream power.
Then the panel voltage would jump back up and the cutoff would turn the output back on.
This dance would happen hundreds of times each morning from what I could tell and eventually killed the pump.
I copied a YouTube design I saw and then just oversized the PV Panel to get more buffer. Guess I got what I "paid for"
Anyway, this year I added the cheap MPPT above and a 12v 5Ah UPS Battery and it works MUCH better.
But the problem is the MPPT doesn't have a Daytime mode.
It's optimized for 24h or Night time operation, more useful for lights or something like that.
I am looking for a way to put this MPPT (or buy a cheap replacement) into a mode where it waits till Dawn + 3 hours and then turns on the load.
By then the sun will be starting to warm up the black tubing enough to be worth it.
Then have it cut off the power at Dusk (or even a bit before).
Ultimately it makes no sense to run the pump through the tubing unless there is enough sunshine basically.
And I fear I am going to kill the batter by running it down to the 10.7v cutoff voltage and then back up to 13v during mid day, every day.
I really just need the battery to handle the "cold crank" if you will of the DC Pump.
After about 60 seconds the black tubing is fully flooded and the pump wattage drops considerably.
My other idea would be to just add a ESP32 or similar with a Relay, and write some simple code to only allow the load to kick in during the times I want.
The ESP32 could be powered by the USB port on the MPPT above.
The Relay would be between the MPPT and the DC Pump.
