For well over a year we have been getting our domestic hot water (DHW) from a DIY solar thermal system. But, last month, one of the collectors started leaking. This was a major fail, and I shut down the system until I could fix it.

Our solar hot water system consists of three collectors on the south wall of our house. Sometimes the collectors are called water solar panels. Inside our crawlspace is a 250 gallon tank I built with an EPDM rubber liner. Water is pumped from the tank, through the collectors when the sun shines. This heats the water and it flows back to the tank. Our potable water runs through a heat exchanger inside the tank so there is no mixing, but the heat is transferred.

The system has been silently working away for well over a year. This is called a "DrainBack" system. All the collectors and pipes are pitched down to the tank. When the pump shuts off, all the water drains into the tank for freeze protection. This has offset 56 kwh of electricity that would have been used to heat water.

To watch the playlist of building the solar DHW system, click here:    • DIY Solar Thermal, DHW  

In the video I have to remove the glass of the panel, find the leak, solder it, and reinstall the glass. I'm using a Bernzomatic torch kit with MAP gas. After several pressure tests I got it to hold.


The system has been up and running again for 3 weeks since the repair. It is holding and no further leaks have been found. Our 250 gallon tank had dropped down to 70°F while it was shut down. Today, it is back up to 130°F. The hottest I've ever seen the tank reach is 160°F

Thanks for watching.

If you would like to help support our channel, please use our amazon affiliate link below:

Torch Kit: https://amzn.to/2W92ka5

“As an Amazon Associate I earn from qualifying purchases.”