Here is my monthly report on how our solar panel system did in July. We have:
- 20x400W panels = 8kW
- 5kW inverter
- 9.5kWh battery
This is not intended to generate all our power as we would not get enough in winter, but it allows us to use mostly cheap off-peak power and export the excess that we generate. Here in the UK we get paid for that at a better rate than what we pay off-peak from the grid. The battery is enough to run the house all day when there is not much sun, but at this time of year we get more than enough to power everything for most of the day.
These are the numbers so far this year. You can see a massive difference in what we generate in mid-winter compared to summer. July had very mixed weather, so we got less sun that we might expect. What we use can vary a lot depending on how many times the electric car gets charged, but we generally use more in winter for lighting and other things. We do not have air-conditioning.
| Month | Generated | Used | Exported |
|---|---|---|---|
| January | 78kWh | 468kWh | 38kWh |
| February | 192kWh | 554kWh | 146kWh |
| March | 619kWh | 503kWh | 535kWh |
| April | 927kWh | 288kWh | 790kWh |
| May | 967kWh | 292kWh | 845kWh |
| June | 1044kWh | 332kWh | 1037kWh |
| July | 878kWh | 309kWh | 858kWh |
You can see the variation through last month. On clear days we can generate over 40kWh. We had another visit last month from the Octopus engineers to investigate our issue with a breaker tripping. They said they tweaked a few things and it has been fine so far since then so we did not lose any days.
So overall last month exported electricity worth £124 whilst paying £55 for what we took from the grid, including standing charge. We also spent £28 on gas. This means we built up more credit to take us through the winter. We pay them £30 each month and I will reassess that payment next year. With some tweaks on how we charge and discharge the battery I hope to make more than last year.
On my Google news feed I see various stories of wind turbines (not 'windmills' as the orange idiot says) that can do a better job than solar panels. They may be things like this that quote figures of several kilowatts. That sounds impressive, but something that size is unlikely to generate anything like that on a daily basis. We will get days with no wind at all and even when it is windy the turbine needs to be up high. Something that was really equivalent to our panels would be two or three metres across and would need to be on a tall pole. It may be too big to attach to the house. That does not mean that people cannot supplement solar energy with wind if they have the space and no close neighbours. Small units can be useful if camping or on a boat where there is no mains power.
There are a few other people posting their solar numbers on Hive:
- @solominer in Virginia has a large installation of ground mounted panels to run his farm. I believe they also power a Hive node and some crypto mining.
- @cryptoandcoffee in South Africa is expanding their domestic system that can get them through power cuts. The power companies are trying to get lots of money out of people with solar, so he wants to get totally off the grid.
- @ksteem is in Florida where there is plenty of sun and running air-conditioning is expensive. His system can also help when storms take out the power grid.
- Slightly different is the @seaexplorer catamaran that is fitted out with panels and batteries so that it can travel around on electric motors as well as running all the equipment. It is used for scientific surveys where they may not want noisy engines disturbing the wildlife and they have less reliance on filling up with fuel.
It is interesting to see what people are doing with solar around the world. The UK gets less sun that some of those places, but we can still save money. Our system will pay for itself in a few years.
Shine on!
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