27 May 2025
Article by Helandi Moolman, Green & You

Would you decline an extra bag of groceries every month?

Probably not. They say we should all be working smarter, not harder. Our spin on it: get your solar system working smarter, then you don’t need to work harder (and can save a bag of groceries!).

Some of the lowest hanging fruits when it comes to solar savings, are geysers. Not only because they consume large amounts of electricity, but also because they mostly get used when there is no or little sunshine. This means that even in households making use of solar power, the geysers rarely get added to the solar system so as not to pull high loads from the batteries at night or early in the morning. In a country still suffering a bit of PTSD from the many hours of load shedding we had over a year ago, protecting your battery State of Charge definitively makes sense. It does, however, mean that your geysers are using expensive Eskom power to heat water.

The opportunity:

Most households waste large amounts of solar power during the day while the batteries are fully charged and the household is sitting idle in terms of energy usage. This is the cue for warming your geyser. Water can actually act like another ‘battery’ – meaning it can store power (in the form of heat) very efficiently. Even more true in well-insulated geysers.

To use your solar optimally – geyser timers or dump load can be used. The latter works with your minimum battery state of charge (SOC) but will not work when Eskom is off. Say you prefer to maintain an SOC of 50%, some days your batteries will reach this charge at 8h00 in the morning, on cloudy days it might take until 11h00. This means your battery SOC (and your ‘backup’ for power outages) always gets preference. Getting your geyser to optimal temperature during the day with timers or dump load, will cost you nothing (thank you solar system!). Your geysers will still be warm enough for hot showers at night or in the morning.

For the sceptics wondering how the math will work, let’s use this example:

Now that you know – that bag of groceries, a nice dinner or even a spa treat is waiting!

Sign up for our monthly Energy Monitoring Service if you’re curious about how much more you could be saving.

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