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£0 a Month to Run a 4 Bed House?

Meet Mr Green, he’s living in a 4 bed house in Newquay and he’s been running an experiment.  He moved in with his wife, 2 teenagers and a baby in July 2013 and did nothing to the house for a year.

A year to the day after moving in he fitted a 12 panel Sunpower system giving him 3.92kWp of Solar PV.  He also had an iBoost fitted which diverts the spare electric to his immersion heater, giving free hot water!

In January of 2015 Mr Green saw, very early on a Saturday morning that he had a full tank of hot water.  Now when you’re a Solar PV owner you know that this means for the rest of the day you’re exporting your energy to the grid.  Energy that you’ve generated is being wasted on your neighbours, and they still have to pay for it.

So Mr Green decided to change his old hot water cylinder for a thermal store.  This would allow the heating to also benefit from the excess Solar PV energy.  Sticking to the social experiment, in July of 2015 Mr Green changed the cylinder, added an iBoost+ which diverts spare electric to two immersion heaters, one heating the top of the tank and one heating the bottom.  He also changed his Solar PV for a 15 panel Sunpower system giving 5.175kWp of power.

The results have been astounding, reducing his current direct debit to £40/month despite signing up to Ecotricity and paying a couple of pence more per unit.   They’re also planning on fitting a Tesla Powerwall battery this July and expect it to half their monthly direct debit.  Mr Green is not a good customer for Ecotricity or any of the energy suppliers.


When What Gas used Electric used Annual Saving
July 2013 – July 2014 No Solar PV installed 639 3426 £0
July 2014– July 2015 3.924kWp Solar PV + iBoost 459 2345 £180
July 2015 – July 2016 5.175kWp Solar PV + iBoost+ 399 1579 £331
July 2016 – July 2017 Tesla Powerwall to be added TBC TBC TBC


Mr Green also gets a Feed in Tariff & Export payment, if he installed this system today that would amount to £375/ year, which covers the cost of all his bills!  So next year, with his Tesla Powerwall Mr Green will be increasing his income from his energy supplier, lucky Mr Green!

This blog was provided by Cornwall Solar Panels