Matching Water Heater Elements to Solar PV Panels

Matching Water Heater Elements to Solar PV Panels
Matching Water Heater Elements to Solar PV Panels

It’s hard to match the solar PV panels to a water heating element. When I first hooked it up I was all wrong and didn’t make much power. But thanks to a friend (Chris), I now have a clear picture of matching PV to heaters. I needed to find the Ohms, Ω, of the resistor.

This is part three of my video series comparing solar thermal to solar PV for heating water. At the end of the experiment I will be sharing my data in case you would like to give this a try.

Now I have three PV panels hooked together in PARALLEL. This keeps the volts the same, but adds the amps. This combination of panels makes the right power for my heating element. I bought a 48 volt, 1500 watt element for this experiment. I am using Y-connectors to make the parallel connections between solar PV panels.

This is a direct connection from panels to heater. There is no MPPT controller in between.

Thanks Edwin for sharing your off-grid system. Edwin is using 6 solar electric panels in parallel to a tank style water heater. e-mail:

I built a free calculator to help everyone out. This calculator will suggest water heater elements for you based on your solar panels.
You will fill in the Volts, Amps, and series/parallel connections. The calculator does the hard part for you. Look on the back of your solar panels for the “Vmpp” and the “Impp”. My FREE online calculator is on my website:

Product links:
MC4 Cable:
MC4 Tool:
MC4 Y-connectors:
48v1500w Element:

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