solar input to buffer tank

[david lawrence]

hi

i have a log boiler which in the summer just does hot water

 

its paid for itself now so getting lazy and sometimes just flick on the oil boiler for a bath

 

any one boost their tank in  summer with solar ?

 

if so is it solar electric then an imersion type heater or directly heating with solar hot water tubes ?

 

any tips or expereinces welcome

 

its a 2000 litre tank

 

not wanting to spend too much as i would be spending to loose RHI money for an easy life

less firewood gathering etc

 

also rather boost the buffer as that would not involve any work in the house 

 

thanks

 

david

 

 

 

 

[Rob_the_Sparky]

Not done it but solar thermal is going to be much cheaper than solar cells, and all the equipment required to feed power into the mains.  One of the reasons for not doing it is that many UK solar hot water systems rely on a mains powered pump and I have never been shown evidence that it would not boil the primary circuit should the pump fail to run (e.g. power cut).  If you have the right locations then the system does not need to be pumped (thermo-syphon instead) so I think this is a safer set-up.

[openspaceman]

2 hours ago, Rob_the_Sparky said:

If you have the right locations then the system does not need to be pumped (thermo-syphon instead) so I think this is a safer set-up.

Yes but then the panels need to be lower than the pump. Also some consideration needed to prevent freezing in winter with any system.

 

Solar PV has halved in price in ten years, are you MCS?

 

I've toyed with solar thermal, even rigged some swimming pool panels from a demolition  to feed a 600gallon steel tank by thermosyphon but wasn't impressed enough to go for it on the house. I reckon I only spend about 60 quid on hot water in the summer months and that doesn't justify a lot of investment.

 

OTOH in the summer my PV produces more than I use and I cannot justify an EV, mind at best it would only get me 60 miles on a sunny day like today. Now sticking 5kWh into my hot water tank would be better justified for the expense of a controller to divert the excess.

[Rob_the_Sparky]

I'm an electronic engineer, no direct link to solar power, just looked at it for my domestic use.  Unfortunately we don't have a south facing roof (only a gable end).  While I could fit some panels, not really enough to justify it + SWIMBO did not like the look of it so ultimately it didn't happen.

 

Solar hot water works best (in cooler climates) using evacuated tubes but these a more expensive than a simple black painted surface with water pipes embedded.  I don't know but would imagine a pool heating system could be the cheaper type, these are commonly used on hotter climates for hot water where the heat loss to the air is not so bad.