grantross

Sorry missed the bit about the power. The unit measures: 1. The power generated by panels eg 1KW 2. useage of house eg 500W My unit has a 150W safety margin to ensure you are not importing power and will dump the equivalent of 350W to the immersion heater. It does this by pulsing only a percentage of the cycle so the the full output is not gained. It may sound doubtfull but it works - checked operation for 2 days checking PV output, elec meter readings and proportional controller. It does not import power on low PV days.

I bought an immersun unit last year about October/November for my solar PV setup. The boiler for hot water has not been on since February and the panels are dumping all excess energy into the immersion heater to heat water. There is still a huge percentage of power getting exported. Checking the unit it is showing 580 KWh have been used since installation. The rest is used round the house or exported. Considering an average year is about 3400 KWh - thats still a huge amount getting exported. When you only get paid 4p per unit for export - I would love my electricity company to charge that for us to buy! Overall I find it a great product that evey solar PV ownerer with a hot water tank should purchase.

Nice vid - and a bit of drive by truckers to boot!