Solar water heating

[Hadenough]

There was an article ref Solar water heating in PBO699 Jan 2024 by a bloke called Jon Walmsley. I have some questions
for him, does anyone have his contact details? I’ve tried all the usual sources including contacting PBO.
TIA

 

[William_H]

Solar water heating is widely used in Australia but does have it's limitations. It needs to be physically very big to capture enough heat during the day for days less than sunny. However this means the system is prone to over temperature during a good hot day. (boils the water with loss of water) The ones used on houses have a tank above the collector panel to get the thermal syphon effect. Hot water rises from the collector to the tank while cold water sinks back in to collector. This is the typical system with collector perhaps 2metres by 1.5 metres often with insulated tank attached at the top. I have also seen collectors where black copper tubes are held in a transparent vacuum tube. Giving better insulation from heat loss to air. They always need an electric element for heating in no sun days.
I think now with solar PV panels so cheap one would be better off with a insulated tank with electric element which can be run from mains power but mostly from PV power. A thermostat giving perfect temperature control.
All of these arrangements are physically big. Suitable for a house roof top but not a boat deck.
Also of some use are a simple black plastic bag of water left in sun all day that will give a nice warm shower. Good some times on a boat.
Not sure what OP has in mind but especially for UK and living away from mains electricity gas or diesel might be best bet. ol'will

 

[rogerthebodger]

I have solar water heating for my swimming pool any home and it works very well but as ol'will said it needs quite a large are to be effective.

A friend did have a similar setup on his 40 ft boat, but he did lack area to heat the water effectively

 

[Minerva]

I built a solar water heater as a project at university some time ago. From memory a board about 0.5 x 1m with a snake of micro bore copper pipe zip tied to it. All spray painted Matt black. Used an insulated demijohn as a reservoir and fed with small low flow water pump running powered by solar. Most flow coincided with most solar irradiation

Got the reservoir up to 50-60°C quite easily but never quite hot enough for legionnaires not to be risk. This was in Scotland in either spring or autumn.

I suspect with some tinkering you could heat the water in your calorifer with a collection panel the size of a 100w solar panel.

Whether using that space for that purpose is worth it when running your diesel engine for 20mins whilst entering an Anchorage would produce Similar hot water is another question altogether. Could be a fun experiment if you have time on yo ur hands.