Thread: Solar water heating
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Default Solar water heating system value
wrote:
samc wrote:
wrote:

Lets say it saves £20 a year heating dhw only.

Would that be 20 UK pounds per year? Sounds like a very poor water heater.
It seems to me that American families pay about $20 per month for hot water.

Welcome to uk.diy Nick. Maybe you can give them a pointer or 2 on how
to make a constructive DHW system that pays its way, too much talk of
junk designs here.

Yes, its 20 uk pounds. I'm not sure how you use all that hot water


NT


Lets say we want it to break even after 10 years, interest is 5%...
A system that does this in 10 years is worth paying £157 for now.

Would you believe 154.43 pounds?

From this emerges one clear conclusion: we need either a lot more
saving or a lot less cost than commercial solar dhw systems deliver.

Or both. Solar water heaters are typically undersized and overpriced.

If one got a bit desperate and justified a 20 year payback, system
value would rise to £251.

Would you believe 249.24 pounds?

Now, since almost all solar dhw setups fail miserably to pay their way,
lets see how low cost we can get. Start with a dirt cheap direct
drain-down system for summer use only.

There's no reason a draindown system can't work in wintertime.

Collector and loft piping:
100' garden hosepipe: £20
sheet of green house polythene: £? Lets say we use a £1 poundland
plastic patio table cover set...

How about a solar-pond type water heater instead?

people are looking at this the wrong way givern the above would any one
ever buy a car,computer,tv e.t.c .

It's more rational to say

I need hot water. What's the most economical system?

Nick

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