If you only require a little hot water (kitchen, bathroom(s), sauna), it is better to fit all taps with electric water heaters or boilers. Instantaneous water heaters generally require large amounts of electricity for short periods of time.
Boilers work better in combination with PV, because the water can be heated when the solar generators produce sufficient amounts of power, and then kept hot for a long time.
Less expensive than gas-fired systems
Provided they use (very) efficient appliances, a four-person household can nowadays produce hot water very economically: For as long as possible, appliances are run on the solar power off the roof. Only when there is no longer enough sun in the autumn, they will switch to green electricity from the grid. This is technically and hydraulically much less expensive than gas-fired thermal systems or solar-thermal water heaters.
44 degrees centigrade is enough
And: Because the boiler is usually installed more closely to the tap, water hygiene is improved. 44 degrees centigrade from the tap is far sufficient for cleaning even the most persistently greasy frying pans. There is no need for long pipes, which also reduces the energy loss and the risk of dangerous germs accumulating.
Electric sub-systems further give greater flexibility as far as changes in demand are concerned, depending on the occupants and their needs for hot water. And some days the house might be of people: friends, children and grandchildren or any other guests. (HS)
Look at this, too:
Solar advice: Match the generator to your needs!
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