[Laura]

While I understand that the answer might vary depending on factors like energy consumption, roof size, and panel efficiency, I’m curious to hear from fellow homeowners who have already gone through the process.

Could anyone share their experiences or insights on determining the right number of solar panels for a residential setup? How did you calculate your energy needs and translate that into the required number of panels? Did you seek professional advice or use any online tools to assist you in the process?

Moreover, I’m interested in learning about any unexpected challenges or considerations that arose during the installation phase. Did you encounter any obstacles in optimising panel placement or dealing with shading issues?

Any advice, tips, or personal anecdotes would be greatly appreciated.

[chptr2archt]

Hi Laura,

We had 12 panels, inverter and battery installed on our roof in 2022 using the Bath Solar Together scheme. We originally chose 9 panels but were advised that 12 was better for us as we had space, and the price of the last three panels was tiny compared to the initial panels (so the more you have the cheaper it gets). We were lucky to have a south facing roof at the perfect pitch of 35-40deg. Our array is 4.4kWp and the battery c. 6.5kWh.

It is important to consider not just the panels but the tariff and way you’ll use it. PV panels without a battery means you either use what you produce (‘live’) or export any excess back to the grid. With a battery you can use what you produce now, or use it later having stored it up. This requires a behavioural change to say run appliances in the afternoon or evening once the battery has charged. Once your battery is full and you’re producing more energy than you can used, you can then start to export and earn money back.

We find that April is the flip-over month from when we start to equalise what we produce off the roof and what we buy/sell. Before April, with little sunshine, you buy in more than you produce, April is even, and after April we are selling more than we use. Therefore it is important you have a good export tariff to make use of this. Octopus, for example offers 15p per kWh (you buy for c. 25p). Alternative tariffs are better suited to running an EV by offering cheaper overnight tariffs, or even flexible ones where you can buy or sell throughout the day.

If you use a lot of hot water and your tank is compatible you can include a solar diverter which sends excess energy created into your hot water tank, reducing the burden on your (assumed) gas boiler.

So there are lots of variables like occupancy, whether you work from home, require lots of hot water…but hopefully that helps a bit?

Alex Bell

[Laura]

Hi Alex,

That’s really helpful, thank you. We are already with Octopus so I’ll look at their tariffs and I will definitely look at the Solar Together scheme and see if there is one in my area.

How did you decide on your battery? What one did you go for in the end?

Thanks,

[chptr2archt]

Hi Laura,

Glad that was useful. My recollection is the batteries came in three sizes, roughly 3/6/9 (or 12?) kWh. 6 was both the mid point for cost and capacity so seemed the best fit. The beauty of the Solar Together scheme is that you don’t need to shop around for suppliers – there’s only one. The downside is that you’re limited to the products they can offer, so there was no choice of panels or battery, just their recommendation. We have a GroWatt battery and inverter, controlled via an app. That said, no complaints from me and the overall process was great. I think we saved 25-30% of the overall cost due to the ‘buy in bulk’ nature of the tender process.

Alex

[Ellen Oliver]

Hi Laura,

How did you get on with your solar energy research? Let us know if there’s anything else we can help with.

You might want to check out our blog posts Are Solar Panels Worth the Investment? and Do Solar Panels Work in the Winter? if you need more information about the investment going into the winter months!

All the best,
Ellen

[Laura]

Thanks Ellen. I’ll check those out. We have been having other work done to the house the last few months so the solar panels have slipped down the list a bit. Is winter still a good time to have them installed?

[Ellen Oliver]

No worries Laura! Lots of people ask if solar panels can be installed over the winter and the answer is yes. They can be installed over the winter and still be effective during the colder months. As they are solely light-reliant, they will continue to generate power over the winter months but you’ll also see a positive difference when the days get longer again in the spring.

Check out our professionals directory for solar installers.

I hope this is useful to you and helps you with your fact-finding. All the best,

Ellen

• This reply was modified 1 year, 10 months ago by Ellen Oliver.

[Energy Chap]

On our last house we had 4 panels, but that is all that would fit as we had a loft conversion. On our current house we now have 25 panels (10.5kW) across 6 roofs and 2 batteries (17.7kWh). We installed in phases due to budget. When the main roof was redone we got a Lendology loan to help install our first 8 panels (3.2kW) and battery (8.2kWh). That first battery was sized to meet out average daily electricity consumption (8kWh). Then a year or so later we redid the flat roof on an extension and got another 4 panels and another 9.5kWh battery. Then a year or so later we went with another 13 panels including on our North East and North West facing roofs. Giving us a total of 10.5 kW. But over the same time our electricity use has increased with phasing to electric heating and an electric car and a plug in hybrid (Plus two teenagers who always have a screen or some sort of electrical device in hand).

We are on the Intelligent Octopus Go smart tariff. With around 95% of our electricity now being from the solar panels or costing 7 p/kWh. Then we get 15p/kWh for export plus some extra for savings periods. We have a good amount of credit on the energy account at this time of year to get us through the winter. While I’m aware Tomato Energy and Edf do better tariff rates. The savings are not enough for us to switch and we do get some extra income from the savings periods by setting the battery to export – about £120 last year.

I do have one regret and that is only having a 3kW output on the battery, but as a family we do well in generally keeping our demand below that level during the high peak period in the day – switching the air to air heat pump or the car charging off when the oven is on and we have smart plugs dotted around to control other devices.

• This reply was modified 1 year, 7 months ago by Energy Chap.

[Green Team One]

Hi Laura,

We find that the best advice is almost always to fill all usable roof space.

Asking how many solar panels you “need” is a misleading question, because it implies that your solar array will meet/match the usage in the house. You can have an array of panels that are forecast to produce 3,500 kWh, and if your usage is 3,500 kWh then this would seem like job done at first glance. But, unless your usage is highly unusual in a very specific way, the seasonal variation will scupper you. An array that yields 3,500 across the year will yield around 480 kWh in July, but around 90 kWh in December.

So whatever size array you get, it’s highly likely that you’ll produce more than you need in Summer, and less than you need in Winter. So you’ll always need the grid.

That all said and done, once you’ve paid for the inverter, battery storage, scaffolding, project management, labour, insurance etc, the price of the panels is a fairly small part of the equation.

We can install 10 panels, a mid-range inverter and a mid-range 5.76 kWh battery for a total price of £8,340.00. Bump that up to 20 panels and you’ll only see the price go up to £10,240.00. For an extra 23% in cost you’ll have twice as many panels, producing twice as much power. Even if that means a higher proportion of the power that you generate is exported at 15p rather than consumed (saving you ~25p), it’s still almost always the best advice to fill all usable roof space.

Warm regards,

Creag

Green Team One

[Author]

Posts