Neutral Home 5: Using the Sun When We Want It
Last week we had the shortest day of the year in the UK, so I chose a great day to switch on our new solar array ! …well its not where you start, its where you finish.
Now we are heating the house with a GSHP but wouldn’t it be good if we could generate the electricity that powers the pump too ? Although I subscribe to Octopus’s Super Green electricity service, can you ever be sure where those electrons really come from? .. Now I can !
We had an existing solar panel array (16 x 250 Wp) generating
4 kW, we have added a further 35 x 330 Wp panels on our newly expanded roof quadrupling our generating capacity. Our roof ridges are sub-optimally East and West facing so we do have shadow issues during the day, so we have opted to add 30 Tigo TS4 optimizers to the array. The optimizer plays a key role in avoiding your whole string of panels reducing generation when one panel goes into shade or partial shade.
A little known fact, amongst existing solar panel owners who feed their power back into the grid for their feed in tarrif is a term called “Deeming”. It's when the electricity companies guess how much of your electricity generated is actually useful ! The normal deeming factor is 50% !..ie you only get paid for half of the kWhs you send !..did you know that ?...I didn’t !!
I want to keep and use all my kWhs so I have installed three 6.3 KWh batteries from GivEnergy in my loft void giving me 18.3kWh in total storage (typically my average summers’ day consumption). I can add further batteries if we need, I suspect we will, but we are going to see how it goes for now. The GivEnergy batteries are quite smart and they can talk to us through an IP address and provide us all the data we need and even figure out what tomorrow’s weather is going to be !
Its very early days but I am excited to see the possibilities. How much of our current demand can we fulfill ourselves ? Will I be able to import cheap energy from the grid between 12-5am and take full advantage of the Octopus Agile Tarrif when they bring it to three phase owners next year ?
I'd like to thank Tommy at Clique energy who has patiently answered all my dumb questions and made frequent trips down from the North West just to stand on our freezing cold roof.