solar hot water back up system

[Happygolucky1]

hi all
4 bathroom property showers and no baths with 150ltr solar hot water system what is best back up system ? electric vrs Gas ? size tank ? etc
thanks
Tel

 

[JohnD]

the energy required to heat the hot water is a small fraction of the energy needed to heat the house.

How do you heat the house? Gas? Oil? Multifuel stove?

Does your solar HW system include a hot water cylinder?

 

[Happygolucky1]

no central heating only log burner, solar with integrated 150ltr tank only no external tanks

 

[JohnD]

you mean you've bought a hot water cylinder with no coil, and a log burner with no ability to heat water?

 

[Happygolucky1]

no additional hot water cylinder only one is integral to solar, log burner already installed no capacity to heat water

 

[JohnD]

that's a pity.

It seems quite odd to go to the trouble of installing a HW system that is useless on cloudy days.

If you want a cheap option, buy an electric shower. It will not be much good. You will probably not be able to run two electric showers at the same time as it would probably overload your electricity supply.

A better solution would be to install a dual-coil HW cylinder that can be heated by your solar panels, and by the boiler when/if you buy one; and also has an upper and a lower electric immersion heater. As you have no baths 150 litres would probably be sufficient, but a larger one will enable you to stockpile more hot water on sunny days and top it up only when needed. Modern cylinders are very well insulated.

Some solar systems will already have the ability to heat from a boiler or an immersion heater, but you'd need to consult a specialist.

p.s.
I see you used to be in Spain. if you are outside the UK say so as conditions, regulations and installations will be different.

 

[Happygolucky1]

ok thanks for your advice, this is on a UK property not my Spanish one