Solar panels can still save you money when it's cloudy — here's how much of a difference the weather makes

(Image credit: Shutterstock)

Everyone knows that solar panels work best when the weather is sunny and the skies are clear, but what actually happens when that doesn't happen? Contrary to what your conspiracy-loving uncle may believe, solar panels do still work when it's cloudy. To be sure, they don't work as well as when the sun is out, but as long as there's daylight, those panels are converting what they can into electricity.I bring this up because last week was the hottest week of the year so far in the U.K., and where I live, outdoor temperatures peaked at around 91 degrees F. Needless to say, the skies were about as clear as they could be, and I took the opportunity to crunch some numbers and see just how much money I was saving by offsetting my electric bill with solar.The past seven days have been a totally different story, though. It's mostly been cloudy and raining, with the sun only making itself known at rare intervals. This got me thinking: how much of a difference has that made in my solar generation, in terms of both power generated and money saved.How solar helped me during the heatwave

(Image credit: Shutterstock)During the recent U.K. heatwave, I was able to generate 145.01 kWh of solar energy over the course of seven days — 59.88 kWh of which was exported back to the grid. My total energy consumption was recorded at 83.02 kWh, 18.5 kWh of which was imported from the grid. Those imports either happened overnight or when my electricity usage exceeded that of my solar generation.Considering my 12-panel array rarely produces more than 2500W of power at any given moment, consumption can overtake generation pretty easily. Usually, all it takes is for a couple of kitchen appliances to be switched on at the same time.Swipe to scroll horizontallyRow 0 - Cell 0 Consumed (kWh)Imported (kWh)Generated (kWh)Exported (kWh)May 229.112.2320.6912.79May 239.532.3718.6310.25May 249.222.1821.6313.38May 2514.012.1921.988.78May 2615.783.6421.418.06May 2714.913.1322.079.03May 2810.462.7618.69.59Total83.0218.50145.0171.88Had I imported all of my energy from the grid, my bill for the week would have been £21.30 (roughly $28.61). This hypothetical figure includes £18.41 ($24.73) for energy imports and £2.90 ($3.89) for a standing charge. This is a daily fee every home pays to cover the cost of maintaining an active grid connection. But, because my solar panels covered the lion's share of my energy usage, my bill amounted to £7 ($9.40) — £4.10 ($5.51) of which was for imported grid energy.Having those panels effectively saved me £14.31 ($19.22) over the course of the week, alongside an additional payment of £8.63 ($11.63) for the electricity I sold back to the power company. In the end, so long as you ignore my gas bill, I ended up making £1.63 ($2.20) of profit over the course of those seven days.Get instant access to breaking news, the hottest reviews, great deals and helpful tips.Swipe to scroll horizontallyRow 0 - Cell 0 Total usage (pence)Grid Imports (pence)Savings (pence)Export earnings (pence)May 22201.9749.44152.53153.48May 23211.2852.54158.74123.00May 24204.4148.33156.08160.56May 25310.6048.55262.05105.36May 26349.8480.70269.1496.72May 27330.5569.39261.16108.36May 28231.9061.19170.71115.08Total1840.55410.151430.41862.56You can argue that the energy I generated isn't free, because my panels are still several years away from paying for themselves. I have only had them for six years, and I don't live in an area known for its annual sunshine. You could think about it as having paid for my energy bills in advance, but no matter what your perspective is, it doesn't change the fact that these panels are reducing my monthly energy bills — especially in summer.What happens when the clouds roll in?