Dump excess solar power into heating hot water.

Описание: I have since started using a new system using solar assistant and home assistant see here
   • Dump excess power into hot water  with sol...  

Warning: This video does not show a thermostat for the water heater which would prevent boiling and avoid explosions. Make sure you know what you are doing if you copy anything.

In the winter the solar hot water panels rarely heat the water up to over 50C. On the other hand on sunny days we have more photoelectric power than we can use. This video shows a simple system to dump the excess power from the photoelectric system into hot water.

It is always good to have the hot water nice and hot. One possible drawback of solar hot water systems in the winter is that it can leave the water for long periods where legionella can develop. I did actually get pneumonia in 2008 but the cause was never proven. So this is another advantage.

Some of the figures in the video were invented off the top of my head. This system may cost 150 euros to implement.

I said sonoff hardware when I meant to say sonoff firmware.

In theory: If the 800 watt heating element was on for 2 and a half hours in a day this would lead to an increase in about 6C in a 300 litre tank.

If the hot water from the tank is not hot enough the water is automatically sent to a gas heater. We use a Junkers Solar Kit. If we can heat the hot water up a little we will avoid using any gas. We very rarely use any gas between April and November and even afterwards we use very little gas.

By the way: If you have very little money to spend on expensive tanks etc consider using a batch water heater which could be almost free if you can find a second hand immersion heater.
https://cortijoblog.com/2015/06/06/ba...

If practice the water at the top of the tank gets heated up so you can get slightly false readings if you have your probe near the top of the tank.
It evens up and mixes by about 9pm.

Note: This system would stop your batteries from equalizing. An equalizing charge is a deliberate overcharge to remove sulfate crystals that build up on the plates over time. Modern charge controllers will equalize your batteries every month or so, in a 24 volt system this means allowing the battery to get up to around 29 volts. So remember to switch this system off occasionally to let your batteries equalize.