I have reached my limit on grid tied solar but want to implement more solar by using off grid applications. I have quite a high and consistent usage of hot water so would like to implement a pre heater tank to feed my existing boilers with hot or warm water. What are my options for connecting a solar array to an immersion directly, via an MPPT? Many thanks!
Lots of options. What is your setup in terms of inverter, batteries, solar?
Also a bit more detail on your existing hot water setup would help.
With a battery and suitably sized inverter you could intermittently dump power into an immersion element based on some simple logic i.e. if the battery is 90% full then turn on the load until say your down to 10%. That can probably be done via an assistant on a Multiplus/Quattro. Or Node-Red automation on a CerboGX.
An air to water heat pump would be a more energy efficient solution to heat your tank but more costly. Air to water in a DWH scenario is COP of ~3 so you would be getting 3kWH hot water from 1kWH PV. A small unit would also draw less power than an immersion element. Only issue is the compressors have quite high startup loads which might not work well with a small inverter.
No loss in conversions, storage, etc... Of course not always the ideal maximum power point either, but who cares, you only heat water... :-))
