One year of solar

I’ve just hit 1 year of having solar panels. What’s my generation been like and how do the finances stack up? Let’s take a look!

When buying solar panels I really didn't have a good idea how my 7kWp system would translate in the real world. How much do I use on a daily basis, how much would I generate, what would the savings be like? Here's my first year in data (July '24 to June '25).

Unsure of the the difference between kW, kWh and kWp? Read my explainer here.

Generation

Solar generation varies hugely through the year, no prizes for guessing that I generate more when the days are longer and sunnier. But day-to-day variation can be massive, more than I expected.

Short, gloomy December days generated 5kwh for the entire day, on average. I even had a few days of 2–3kwh. This is somewhat below my daily consumption (see below), but that’s still electricity that I’m not buying from the grid.

Through January and February I was generating more than I used only about 1 in 3 days. But the bright days are really bright. A short, cloudy day in Jan or Feb generates around 5kwh for the day but the bright days were 4–6x that, far more than I was using.

My solar generation was higher than my consumption, on average, by mid-February. Earlier than I expected!

Generation really ramped up in Spring. I was regularly generating 20–40kw per day, far exceeding consumption so I could sell lots back to the grid.

I reached near ‘full generation’ in April, earlier than I expected. I averaged around 37kw per day in April and stayed at similar levels until  June.

July and August (jumping back to 2024) were a little lower at 33kwh for average days, before gradually slowing through the Autumn.

Power consumption

Consumption (sometimes called ‘load’) is more individual than generation, but I think helps to put generation in context. 

On days that I don’t charge my plug-in hybrid  car then I use 8–9kw per day. That includes things like the washing machine, dishwasher etc.

When I charge the car the load spikes (see chart) but it's infrequent as I don't drive loads. 

Compared to generation, electricity usage is much more stable through the year. This is going to depend on the country and whether your heating system is electric, like a heat-pump, or gas. Like most in the UK, I don't have air conditioning and my heating is gas-powered.

Net generation

Net generation — or generation less consumption — is also specific to me because it's based on my electricity use. But it’s important for understanding financial savings from your solar system.

In my first year I generated 4830kw (4.8mw) more than I used, or +13.2kw average per day. 

That’s pretty amazing. I’m generating more than double my consumption through the year, even including dark gloomy days.

At some points net generation is a lot more (see chart). In fact, it’s only a very short period in which I use more than I generate.

If you’re thinking about solar as a way to reduce your carbon footprint then this is a BIG win. Especially considering it covers the majority of my car travel too.

Savings (the really big one)

This is the one that most people want to know. How much do I save by using solar panels? How much do I sell back to the grid? What’s the pay-off period or rate of return on solar?

This of course depends on your energy tariff as well as other things, but importantly I’m not always targeting maximum £ (sometimes I just need to charge my car, not wait for the cheapest time, etc). 

I think my usage is fairly normal. I haven’t switched my main meal to lunchtime for example, so hopefully this is fairly representative of normal use rather than extreme lifestyle choices.

The financial side of solar can be broadly split into two parts:

1.  Exports (sell to the grid)

2. Savings (how much I would have paid for electricity if I didn’t have solar).

I can’t quite do a full year yet as there were a few weeks between installing and starting to sell (fairly standard in the UK). But with a couple of weeks to a complete year for that data, I have sold just over £700 back to the grid.

I've also saved just under £700 from the energy that I’ve used but not paid. So for the year as a whole I've saved+sold around £1400. 

£1400 in a year sounds great. That could go towards a family holiday or that new TV you wanted (which you can watch guilt-free knowing it’s powered by the sun!)

Rate of return / pay-off period

I paid around £10500 for 16 panels + battery (and the battery is key for the £700 of savings). I was actually able to claim £1000 back from my mortgage company, despite not getting it through them at all - worth looking into.

What’s the pay-off period on my solar panels? Based on my first year, I'll fully recover the cost within seven and a half years, or less if energy prices rise.

But I think pay-off periods are the wrong way to think about it (as I explain here). I prefer to think about it as a rate of return.

My gross rate of return is 13.3%, tax-free (£1400 in year 1 vs initial cost of £10500). If you're being thorough, you could subtract some for depreciation. Panels add value to most properties, but over time that will become less as the system gets older. Let's subtract 5% of the cost (£525) per year. Now my return is £875, or a little over 8%. Again, that's tax-free. 

Compared to what you get in a savings account, that’s fantastic!

So, my solar friends. There’s much more that I can delve into, but with a fantastic rate of return like that, I’d say that my first year of solar has been better than I expected. You can follow along with my live solar panel statistics here.