Solar Hot Water : Why don’t I have hot water when it’s cloudy?

no hot water when cloudy

Solar hot water system troubleshooting.

After weeks of hot weather and ample sunshine, as soon as we experience a few days of rain and cloudy skies we are guaranteed to receive an increase in phone calls from solar hot water customers complaining they have no hot water all of sudden. Many are often perplexed as to why their hot water supply seems to come and go – one day they have ample hot water, then the next none. Why does this happen?

how solar hot water works
Hot water heated by the sun

Why do I run out of solar hot water when it’s cloudy?

Solar water heaters work by absorbing energy from the sun’s rays in the roof mounted solar collectors and transferring this to heat water stored in the tank.

Ground mounted direct systems rely on an inbuilt circulator to push the water through the system, whereas roof mounted systems rely on a natural ‘thermosiphon’ effect. Water passes through the solar collector where it is heated, then moves out of the collector and into the tank. The tank gradually gets hotter until the water reaches its maximum stored temperature.

All solar hot water systems come with a gas or electric back-up system that will continue to supply hot water during cloudy days and prolonged periods of low sunshine. If there is a problem with the backup systems then, on cloudy days when there isn’t enough sunshine to heat the water via the suns rays, you are likely to run out or experience no hot water.  Then, when the sun returns, so does your hot water supply.

When we experience weeks of sunny skies and warm temperatures, many people don’t even realise there is a problem with their solar hot water system. It is only once we have a few days of inclement weather that this is brought to their attention and hence we receive an influx of calls from perplexed solar hot water users.

The problem is usually not with the entire system, just the gas or electric back-up.  Typically the repair involves replacing the broken or worn parts and the customer is back experiencing trouble-free solar hot water – rain, hail or shine!

Helpful readingSolar hot water backup system repairs »

No solar hot water? Running out of hot water when it’s cloudy?

We are the Sydney solar hot water experts. We are authorised installers and repair technicians for all the solar hot water heater brands including SolahartRheemEdwardsApricusQuantum and many more.  Our solar systems are competitively priced because we purchase large quantities direct from the manufacturers – a saving we can pass on to our customers.

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The information on this website is of a general nature only. We do not make an warranties about the completeness, accuracy or reliability of this information or whether it is relevant to your specific hot water problem(s). For professional hot water repair advice specific to you, contact our Sydney hot water specialists direct on 0410 693 532.