What is a

Hot Water Diverter?

A hot water diverter is a simple device that monitors when power from a Solar PV install is sent back to the grid.

When the home consumption is insufficient to use all of the generated power from the solar generation, the surplus power. is returned to the grid. For Example, your Solar generates 1kw of power, but the home only uses 500w there is a surplus of 500w.

The hot water diverter will turn on the immersion heater and use the surplus power to heat your water.

We currently use two types of hot water diverters currently, the Solar iboost and the Eddi. We have carefully selected these as our two options, the iboost is our more economical option and the Eddi is our premium option.

iboost vs Eddi? What’s the difference


The iboost is a very robust and simple device. The iboost will simply measure the amount of power going back to the grid and turn the immersion heater on to that amount.

It allows you to input a schedule for your hot water in case the immersion heater is your only way to heat the cylinder, this covers you for the winter or dull periods when there may not be enough surplus power to heat the water.


The Eddi does all the above but is much more intelligent and programable. The Eddi will work in conjunction with a battery allowing you to decide if the battery or the tank receives the surplus power first. The Eddi will also work with any type of heating system, the I boost cannot work along side an air source heat pump.

Eddi is made by a company called MyEnergi, they also make an electric vehicle charger called Zappi. If you already have a Zappi or want to make sure you have a system that is compatible with one in the future, then the Eddi is the device to go for. Eddi can talk directly to the Zappi as it is within the same product family.

Eddi will also allow you to monitor what is happening via the MyEnergi app. As homes look to become smarter with their power the Eddi is a device that is ready for that to happen.

There are a couple of other things that the Eddi does that the I boost does not:

  • Allows connection of electric heaters as well as an immersion heater.
  • Has an E-sense input to allow automatic heating of the tank/ heaters when the lower cost electricity is active within the home.
  • Allows the addition of a temperature probe to be connected from the tank to the Eddi to let you know the temperature of the water in the tank.

I don’t have a hot water tank or an immersion circuit?

An iboost hot water diverter will only work if you have a hot water cylinder. A hot water cylinder can be added to your boiler system.

An Eddi hot water diverter can work with electric heaters as well as immersions, however if you want to heat hot water then the above points explain how this can be done.

If you have a hot water cylinder but don’t have an immersion heater circuit wired in, then just let us know and we can price to install this for you.

What type of boilers are compatible with the energy diverters?

In theory all boilers can be compatible with an energy diverter. The easiest system to integrate an energy diverter into is a system boiler as that already has its own hot water cylinder. The fuel type of this boiler can be anything as the diverter does not actually integrate with the fuel, it works via the electrical immersion circuit that is usually installed to be a back up to the boiler.