Does Solar Power Work On A Cloudy Day? (Video)

Does Solar Power Work On A Cloudy Day?

Yes, it does. So I’ve actually got a slide here to help show what can happen across the day when there’s some cloud cover.

This system has quite a few panels facing west, and this graph is from a day in winter. As you can see, it’s pretty slow to get going, but then the output starts to increase and peaks at about midday.

The big increase in power came from two things. Firstly, the sun got a bit higher up in the sky and so there was direct sunlight on the panels, that’s really important for solar power.

So you want direct sunlight on the panels. And the second thing was the clouds went away.

This is a 5kW system and can see it peaked at 4kW. Importantly with a solar system, it often won’t peak near its rating. So if you have a 5kW system, for it to output 5kW at any one time, you need it to be the right time of year so that the panels are facing directly at the sun.

For example, if the panels are flat, they’ll work really well in the summer, but in winter they won’t work as well compared to the average.

If you’ve got the right angle at the right time of year, plus it’s sunny and it’s the middle of the day, then your system can get right up to its rating, for example, 5kW of output from a 5kW system.

Next, in this example, at around about 1pm or so the clouds come back and the system drops from 4kW down to about 2kW, and then even down to 1kW of output when it started raining.

The clouds then went away and so the output shot back up again, but then it really dropped off as the sun started to set quite early as it does in winter.

So that’s a bit of an example of what can happen across the day, and that’s why it’s we always say two things; one is size up a system based on averages, and secondly, it’s really good to have proper online monitoring with consumption monitoring.

This way you can look at the monitoring and see what your solar system is doing compared to how much electricity you’re using in the home, and then make decisions based on that. 

For example, with a smart solar system with Enphase microinverters, you get very good monitoring, so you can see what’s happening at a specific time such as ‘now’ or ‘an hour ago’, but then you can also get a really good idea of trends, for example, what’s happening on a sunny day, or for example how much electricity am I using on the weekend, or if I’m not home, or if I turn on the air conditioner. You can start to get a really good feel for how much power things consume and how much electricity you actually generate from your system based on the weather.