Solar and Battery in 1960s House

Solar Panels and Immersion Heater Diverter System

In 2014 we had Solar Photovoltaic panels installed on the roof. The system is oriented East – West because of the pitch of the roof and consists of 13 panels (Renesola 255W with Solar Edge inverter and voltage optimisers), 3 panels oriented to the East and 10 to the west giving a combined capacity of 3,32 kW. On average the panels generate 2.74MWh of electricity per year over the past years. The only major down time was the period of extended snow one year which covered the panels.

10 solar panels on the west facing roof aspect

We receive payment via the old Feed in Tariff system, which is no longer available, but amounts to several hundred pounds each year. Note that higher output panels are available these days.

At the same time we also installed an immersion heater diversion system which redirects excess power, that would ordinarily be exported to the grid, into the immersion heater to heat the hot water tank. In the summer this can be sufficiently effective so that we don’t need to heat the water using oil.

This system was installed by Midsummer Solar from Cambridge but they no longer install solar.

Solar battery storage with inverter

Battery Storage and Car Charger System

In Autumn 2021, we added to this system through the Essex Solar Together initiative by installation of a battery storage system and an Electric Vehicle charging point. The installation was contracted to Greenscape Energy who had the contract from Essex. 

The battery system consists of 2 Pylontech batteries providing 4.8kWh of storage that is fed by excess solar generated electricity that would otherwise be exported to the grid by an inverter system. The batteries are 442mm x 410mm x 89mm in size and are stored in a rack system in the garage which is expandable. The way this works is that when the solar panels are generating more electricity than is being used in the house, it is stored in the batteries, and then this power can be used when there is additional power demand either because demand exceeds the solar generation, or in the evening when we would normally have to draw electricity from the grid. For a sunny summer’s day this mean that we effectively use no electricity from the grid as it is either supplied by the solar panels or from the battery in the evening sufficient to last until solar generation starts up again the next day. This is a game changer, because you can use the vast majority of the electricity you are generating from the solar panels rather than exporting it to the grid, and under the feed in tariff you still get paid for potentially exporting it. Obviously in the winter or on cloudy days you still need to use grid electricity, but the system still provides extra power on a sunny winter’s day.

In addition we installed a Zappi 2 electric car charger. This is able to detect both solar power generation and call on power from the battery, so can charge an electric vehicle without using grid power, albeit slowly. If you need to charge more quickly at 7kW, more power must come from the grid. 

Overall the system is now set up so that solar power is used for the load in the house first (including the car charger if that is running), then directed to battery storage if there is excess and finally to heating the hot water via the immersion heater if the batteries are full. If there is then still excess power it is exported to the grid. 

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