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I Use 25kWh A Day. What Size Solar System Should I Buy?

Author
Tom Sedgwick
Updated at
Reading time
3 min

I could answer that one in 10 minutes but I will try and keep it quick.

Firstly, if you want personalised numbers, give us a call on 1300 525 451 and we’d love to help. It’s fun to help find the right solution for a household.

The way we size our system these days is if you’ve got 25kWh of usage a day, a large system, like a 10kW system actually makes good sense. So firstly, the system’s going to output enough electricity in the winter to cover your bill, and then we try to size the system up to meet your 24-hour usage rather than just your daytime because there’s a lot happening at the moment.

In the next few years, most people are going to be installing battery storage, we’re already well over 50% in most months where our customers include battery storage, and almost everyone now is buying a solar system that’s large enough to be able to power your home during the daytime, and then produce enough excess solar power to charge the battery, so that you can then use the stored power in the evening.

So the other thing that is happening is electric vehicles are coming. My colleague just ordered a plugin hybrid, actually, they’re coming too. So you want to make sure that you’ve got enough electricity to not completely, of course, charge your EV, but certainly in part. And then of course, the other thing that’s happening is these VPPs, virtual networks where you can sell power to each other.

At the moment, you basically need a battery to be able to do that and then give control of the battery to a third party. We’ve partnered with Evergen, for example, and they’re doing a fantastic job for hundreds of our customers that have, Tesla Powerwalls. If you’ve got a really big solar system, you can put additional solar power into a battery, but then sell it at a premium through the VPP at times when the wholesale power price is really high.

So instead of getting a little feed-in tariff for the excess solar, you’re actually getting quite a good amount of money for being a part of a virtual power plant. So that’s all exciting and coming along very quickly.

So that’s why we’d recommend a 10kW system and why so many people are doing it.

If you wanted to go for a smaller system, you can basically just divide your usage by four. So if you’ve got a 25 kWh usage, divide that by four, and you’re probably looking more at like a 6.6kW system. On average that will give you about the power you need, it will be a little bit too small in winter, and that can be a bit of a problem if you use a lot of electric heating because that winter bill can still be pretty big if you use a lot of power at night and the solar system’s not producing enough power to cover your usage during the daytime, but then in summer, you’ll have a lot of electricity to make use of.

So you might have a bigger bill in the summer if you’ve got air conditioning or pool pumps and that type of thing, then a system like that can be a good size. So that’s why we kind of say, give the team a call and have a few bills handy. Our number is 1300 2525 451.

Again, if you have a rough understanding of how much power you are using in the winter and how much power you use in the summer, we can help you size up a system. And of course, we’ll talk about what I just went through there including if you have plans to increase your usage. Because a lot of households do and sometimes they don’t even know it.

It’s like, oh, well, yeah, I was planning to get an EV next year. It’s like, well, let’s make sure we get you a solar system that can accommodate for that.

So there’s a few things that we can take into consideration to make sure we get you the right system.

We can add panels down the track as well with Enphase, which is great, however, it’s good to get it all done at the one time. That way you’ve only got one installation fee. So it’ll save you a bit of money, but down the track. If you’re going to add a battery, we can come back and put panels on the roof too. So hopefully that helps.

Request for a solar and home battery storage quote today to see how much you can save!

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