Solar Immersion Switches

If you’re considering or have already installed solar panels on the roof of your home, you’ll be aware that some of your generated electricity will be lost to the grid through export. This is common among domestic properties and the reason why deemed export is currently paid (for half of your generation). But, there is a way to combat this loss and it won’t affect your export or Feed-in-Tariff (FIT) payments.

Solar immersion switches (also known as solar switches) are connected to your solar array and the immersion heater in your domestic hot water tank (if you have one). They work by detecting when excess energy is being exported to the grid and diverting it to the immersion heater where it is stored as hot water. Of course, some energy may still be exported, but only once the tank has reached the desired temperature (normally 60 degrees). This not only means you’re getting the most out of your generated renewable electricity, but also saves you money importing electricity or firing your boiler for your hot water.

Having installed a number of different makes and models of immersion switch over the years and have settled on two products which we think are the best on the market.


With over 45,000 Solar iBoost controllers installed in the UK, this model is adaptable and cost effective to install. The unit works by clamping onto your household meter and sending signals to the receiver, which in turn directs the surplus PV generation to the immersion heater in the hot water tank.

For homeowners interested in understanding what previously exported energy they are now using, the iBoost offers a monitoring device. The unit comes with an inbuilt display, showing daily, weekly and monthly figures.

Upgrades are also available for the system, with the option of adding remote monitoring for your controller improving usability and flexibility within the home. The iBoost Buddy alerts users when there is excess energy, allowing for appliances to be turned on at peak times, whilst also displaying the financial benefit of using the system.

The Solar iboost can be installed at the time of a new solar installation or just as easily retrofitted to an existing installation. Typical costs for a retrofit installation would be around £450.


SolarEdge provide impressive monitoring solutions for solar PV installations, allowing homeowners to monitor each panel of their array remotely, through their mobile app or desktop site – and now they’ve integrated their own version of an immersion controller. The first thing to note is that the Solar Edge Immersion Controller can only be used with a Solar Edge PV system. It can be retrofitted, but only on SolarEdge systems.

The SolarEdge model works in the same way as the iBoost by diverting any surplus PV generation to the immersion heater. However it has some additional features accessed through the sophisticated SolarEdge monitoring portal where you can monitor PV generation, export and consumption. The data is easily visible in graph format and allows users to identify behaviour patterns to maximise energy use. If this all sounds a bit geeky, it is!

This controller will only work with an installed SolarEdge system, so isn’t suitable for existing systems without it unless there is an upgrade. But, as part of a retrofit application, it makes great sense and allows users to get the most out of their solar installation.