These seven south-facing photo voltaic panels had been put in in early July 2025 so we’ve had them, and the battery they fill when our electrical energy manufacturing is bigger than our speedy want, for simply over a 12 months.
In a single day, when there is no such thing as a photo voltaic technology, we use no matter electrical energy is saved in our battery after which change to the grid. Through the day, there can be photo voltaic technology (heaps in summer time, little in winter) and the battery will get a prime up.
As of yesterday morning, our photo voltaic panels had produced three quarters (75.8%) of the electrical energy we used within the 12 months (proper hand column, consumption, beneath). We’re paying Ecotricity for the 24%, a few of it on the day fee and a few of it on the night time fee.
Greater than a 3rd (35.85%) of our home technology (left hand column, technology, above) was exported to the grid as a result of our battery was full and we receives a commission by Ecotricity for that at (now) 16p/kWh. Our residence’s carbon footprint is lowering and we’re contributing inexperienced power to the grid.
However what of the cash? It’s not fully simple to do the comparability, or to work out how a lot one is saving in actual time. Why not? Electrical energy costs change, so with what do you evaluate? It’s not simply what you pay that modifications, it’s how a lot you receives a commission for export too; Ecotricity’s 16p/kWh got here in lately. And, one’s behaviour modifications too – we’ve intentionally shifted, modestly, in direction of utilizing extra electrical energy (as a result of it’s low-cost and inexperienced) and fewer gasoline which ends up in gasoline financial savings that are tough to estimate. Additionally, we now gladly ‘enable’ guests to recharge their electrical vehicles from our battery – a small value to us and a a lot greater saving to them. And slightly prosaically, one’s electrical energy payments come month-to-month (however, in fact, weren’t synchronised to the day that the photo voltaic panels started to work) and our funds for export are paid quarterly and there was a delay in getting an export contract as a result of Ecotricity had been rejigging their charges when our panels went stay.
Nonetheless, I estimate that we’ve saved round £800 off our payments within the final 12 months (and I haven’t carried out the changes for gasoline or car-charging largesse, nor actually have I constructed within the value will increase). At the moment, we’re paying extra per unit of electrical energy we take from the grid than a 12 months in the past (so it’s good that we will restrict their quantity) and we’re getting extra per unit we export to the grid than after we began. That looks like the long run too though who is aware of?
The price of getting panels put in was about £9,000 and so I might calculate how a lot curiosity I’m shedding from that sum to set in opposition to the financial savings. Nonetheless, the £9,000 determine contains (as defined in a earlier weblog) the price of eradicating previous photo voltaic heating panels and the price of scaffolding that was used to provide entry to workmen doing different issues to the roof. I believe an attributable value of £7,000 sounds about proper which might be 9 years, roughly, payback time – longer than the 5 years that’s talked about when one indicators up. Nonetheless, that’s utilizing the primary 12 months as a measure and we finish that 12 months, I repeat, being paid extra for export and paying extra for grid electrical energy. You may suppose, issues can solely get higher as a result of each export funds and import costs will proceed to rise. What’s going to they be in 5 years time?
We’re very more likely to get an electrical automobile (and that won’t be low-cost to purchase, and we’d want a charging level) however will open up extra day-on-day financial savings.
All of that is predicated on the panels persevering with to work.
The economics are a bit sophisticated however we didn’t resolve solely on financial grounds. We’ve gone greener by having photo voltaic panels and that’s value an funding of our money, similar to it’s value an funding of the nation’s money to ship lowered carbon emissions.
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