Solar power diverter
There are other Solar power diverters, but I went for the myenergi eddi, so this is about that one only.
According to the myenergi eddi website.
Save money and energy with British made power diverter
Use your excess energy and save
Bring an eddi into your home and you can make the most of the 100% green energy generated from your solar PV or wind generation system.
Rather than exporting excess generation back to the grid as per a standard PV system, with our intelligent eddi power diverter, that extra power generation is instead diverted back to your heating systems, thus heating water on 100% self generated green energy.
It is a simple concept, but a wiz bit of Tech.
How does an energy diverter work?
It monitors the Grid connection and as soon as you start generating more electricity than you are using, as soon as you start exporting, it turns on the immersion heater in your hot water cylinder, creating an additional load, and stopping the export. If you turn something else on it the house, it reduces the power going to the immersion heater by that amount. It only uses self generated electricity that would otherwise go as export to the grid.
It stores the surplus electrical energy produced in the form of hot water.
To maximise the storage capacity, you would have cold water to start with and a very large cylinder or Thermal Store. However, there are some impracticalities with that, including the potential of cold water to wash with in the morning before any diversion had commenced.
Of course such diversion into hot water can not continue indefinitely. A home with super heated steam in a cylinder is not a safe option. The thermostat attached to the immersion heater would close the circuit. For the avoidance of doubt, not the one for the cylinder, which controls the Domestic Hot Water side of the Central Heating. At that point, with self use of electricity being less than the PV panels are generating at that moment in time, and nowhere for the power diverter to divert to, export of electricity would commence.