Solar To Heat Water Spain

zeupater

silverwhistle wrote: »

Your set up up may well be like the flat I rented in Italy where hot water was supplied from a tank above the bath heated by an immersion. A small heater given that the total load for the flat maxed out at 3kW (actual 3.3), and would trip the smart meter if you went above that. No English electric kettle!

It's a shame you couldn't use a 12 volt immersion (they are available) and direct from a couple of PV panels with no inverter or similar costs and no complicated plumbing changes. I imagine you'd want to use mains to top up with during certain seasons. If you had a UK type tank with two inputs it might be possible.

Those more technical than myself might see other objections.

Hi

The issue is that all we know is that there's 50litres of water to heat ... if there's little water drawn daily then it may be possible to build the heat up over a number of days, but if the usage is (say) 100litres/day then it's a different issue ...

50litres isn't much, so if usage is anywhere near average then heating the DHW purely on solar (ie no back-up, linking the existing immersion to the PV ) isn't going to work well at all, but if it's for (say) hot water to a sink in an outbuilding then it's a different issue ...

My guess (and it's purely a guess!) is that the OP doesn't fully understand the capabilities of solar PV related to surface area (/size) ... roughly (rule of thumb) - 1kW for 1Hr raises 1tonne by 1C, so for 50litres of storage with daily 50litre depletion you're really talking about something in the region of 3-4kWh/day, so low usage (sink&heat-loss) could be ~1-2kWh/day and 100litre usage maybe up to 8kWh (50litres = cold water likely in the morning!)... so a range of 1kWh to 8kWh, the difference between a single (say) 200Wp panel & something like a 6x250Wp panel array - that's why the Op needs to provide more details to describe what kind of solution were being asked to comment on!

HTH
Z

pile-o-stone

I wouldn't have thought it was financially worth using solar to heat 50l of water, especially with solar PV as he'd need solar panels, an inverter and then an immersun type device to attach to the immersion heater. Instead, the OP should increase his solar aspirations and use the energy to power his home, with the excess diverted to his tank. This would be financially viable, especially in Spain.

I wouldn't fit solar thermal under any circumstances. It's a system that tries to self destruct in Summer when water in the panels stagnates and boils or in Winter when the water in the panelsl freezes and expands. The costs of installing is more than PV and the energy produced in of low value. There is also on-going maintenance with Solar Thermal, whereas PV is pretty much fit and forget.

zeupater

pile-o-stone wrote: »

... I wouldn't fit solar thermal under any circumstances. It's a system that tries to self destruct in Summer when water in the panels stagnates and boils or in Winter when the water in the panelsl freezes and expands. The costs of installing is more than PV and the energy produced in of low value. There is also on-going maintenance with Solar Thermal, whereas PV is pretty much fit and forget.

Hi

It's a view, but only a view ... a decently designed system wouldn't stagnate much, wouldn't boil (pressure!) & wouldn't freeze (glycol or circulation!) ... cost is (/can be) less than PV & the energy can be valued by comfort or displaced fuel ....

I know of a system which was installed in the 1970s and is still working with very little maintenance, however, I do agree that PV provides a far more versatile solution, which can accommodate DHW and other requirements.

An issue often overlooked is the relative efficiencies (KWh/sqm) of the panels .. if the OP is limited on space (and it sounds like it!) a thermal solution would likely provide a better match.

From the lack of responses & information, my guess is that the Op initially thought that a couple of small 12V/12W type panels & some innovative wiring (so ~£100) would do the job ... it's just that it won't! ... :cool:

HTH
Z