Solar Hot Water System

[sailormed]

This is a solution looking to find a problem to solve. When you have the sun shining the whole day you are glad when you have cold water to cool you off. Just my 2 cts.

[coopec43]

This system does not have a pump but my intuition suggests it would be better with one

https://www.youtube.com/watch?v=1tTtPLGjOJo

[coopec43]

Maybe a few ideas here?


https://www.builditsolar.com/Project...m#Thermosyphon


Is anyone heating water using solar and black plastic piping ? (pump, greenhouse) - Green Living -Sustainable living, ecology, conservation, local agriculture - City-Data Forum

[mako]

Originally Posted by coopec43

There are different studies of

Solar water heaters Vs solar panels/electricity/heater element

But they take into account life span of units and capital cost which I dion't consider relevant in this situation.

I was speaking with my architect who is building a passive-haus in Madrid. He is required to provide a certain percentage of his hot water from solar, and have a certain amount of PV electric as well. So I was surprised to learn from him that he, and others building new in his area, all are using solar electricity, not solar hot water collectors. "solar panels/electricity/heater element"

It makes a lot of sense in so many ways.

Those Europeans know more about energy conservation then us Yankees will ever know

[fatherchronica]

I had planned to build a solar water heater that would be a long skinny black sack, surrounded by a clear sack that I could hoist up the mast with a halyard, thus supplying hot water and water pressure at anchor, which is the time I am most likely to want a shower. But being busy with other projects and leisure activities I settled for an H20 brand water heater and a few gallon water bottles painted black.

[senormechanico]

Originally Posted by Dave_S

Why do you need a pump to circulate the water ?

If you have the storage higher than the heating panel the coldest water will sink to the bottom back into the heating panel where it gets heated and rises to the storage, when it becomes cooler than the water around it, it sinks again.

Take the water to the taps from the top, water supply in at the bottom.

Trapped air will automatically purge when used.

Not practical on a boat. The trapped air stays in the panel unless the outlet hose is uphill to the tank, or you have a LOT of recirculation flow.


As posted, I have done both a water recirc system and straight electrical with an inverter. The first one on a Lord Nelson 35, and the second one on my current boat. I much prefer the electrical/inverter system.


Post #11 describes the recirc system I used on the Lord Nelson, but I made a 2 x 4 foot panel from copper pipe painted black and enclosed in an insulated frame with polycarbonate cover. It was mounted in the middle of my solar array and the 12 volt March pump was controlled by a differential controller. Totally automatic hot water, but I had to burp the panel every few days. You should have seen the looks I got when people saw our solar array "peeing off the stern" !

[Luc bulterys]

A French company sells a similar system. They have a small dedicated panel just for heating water, or a hybrid panel. But then you need enough place of course for such a big panel.
But even if you are not in Europe, the system itself can be inspiring ...
I was considering it, but finally decided to use electricity (no extra cost) and invest rather in enough solar panels and batteries for general use.
https://www.green-yachting.eu/les-produits?lang=en

[nwdiver]

Black plastic barrel on the fore deck........or solar shower type bag that is bigger, roll it out fill it use the water end of day roll it back up store it........KISS

[Hardhead]

Originally Posted by coopec43

This system does not have a pump but my intuition suggests it would be better with one

Great video - simple idea and cheap.

[Luc bulterys]

Originally Posted by nwdiver

Black plastic barrel on the fore deck........or solar shower type bag that is bigger, roll it out fill it use the water end of day roll it back up store it........KISS

Forgot to mention it: We also have such a black shower bag. If not too long in the sun, it works fine. It can get really hot though. But it is only a few $€

[noelex 77]

Heating water via the main engine is a pain if you typically anchor for several days or more at a time, so thinking about a system such as this is sensible.

There is a simple system, still with the advantages of a “proper” shower. Store the water on deck in the sun in any (preferably dark) plastic container. Pour this into a tank or bowl. Mix to the desired shower temperature by adding cold water and use a small submersible pump in the tank/bowl to feed a shower rose. You can prchase cheap units from eBay already made with 12v pump and shower rose.

As well as simple, it is a very versatile system. If the water is a little too cold you can mix in some hot from a kettle. A perfect shower temperature even on the less sunny days. As the water temperature is pre-mixed it saves water as there is no wastage adjusting the taps. The bowl and pump can be built into the shower area for a more permanent set up if this is desired. As there is no external plumbing, pump to circulate the hot water or permanently fitted solar collectors etc it is still a very simple reliable system. The solar collectors are simple disposable water containers so they can be easily replaced when the UV damage becomes an issue.

It produces a luxurious shower that is just the desired temperature without any adjustment or change even as the hot water approaches the end or if someone else turns on another tap. The main advantage of not having the noise and heat of the engine is the same as any other solar system.

[RaymondR]

A little add on the the system I am contemplating.

One of the things I find annoying is the amount of water I waste whilst waiting for the hot water in the hoses to displace the cold. The solution used in buildings for this problem is to install a return line through which the hot water is circulated so that there is only a very short run of pipe between the hot carrying pipe and the tap. I am pondering on how to fit this into my circulation system for the solar collector addition.

[foufou]

The simplest solar water heater is the black plastic bag style that can hang from the boom. In warm climates these work quite well. If you want to extend the reach of the shower a length of vinyl hose and couplings should do the job. But adding a heat collection system as the one sold by Custom Marine Products can produce a lot more hot water. And no extra deck real estate is required. Additionally a thermo siphon should be easy to achieve. These can be problematic because the pressure developed is so low it doesn't take much of a bubble to prevent flow. Good geometry is essential. No dips in collector to tank plumbing. And the tank should be a couple of feet above the collector. The 4'X8' collectors I have built can heat 30 gallons of water to 120F in a day. 4X8 is likely too large to be fit on a boat but its heating capability is a good reference. Attached to the back of a photovoltaic panel is a wonderful idea and could bbe useful for houses as well as boats

[senormechanico]

Originally Posted by RaymondR

A little add on the the system I am contemplating.

One of the things I find annoying is the amount of water I waste whilst waiting for the hot water in the hoses to displace the cold. The solution used in buildings for this problem is to install a return line through which the hot water is circulated so that there is only a very short run of pipe between the hot carrying pipe and the tap. I am pondering on how to fit this into my circulation system for the solar collector addition.

I just start by washing my feet and working up from there.
The heated water runs back down to warm up my feet.
When I'm done, I'm all toasty !

[Mike Banks]

There aree ways of making scalding hot water by solar--but the system you want will not tolerate really hot water or pressure, so why not just lie some camping hot water shower bags on top of wherever the sun is, but pout them on some insulating material so that the heat stays in the water and not passed into your cabin or deck. IU used two of these when my hot water service packed it in. I use on demand gas, but if I were to travel into remote areas I would build another solar system using an insulted storage system, recirculating pump and thermostat bypass. Forget about plastic--hot plastic will burst with pressure.you need metal cylinders, although they can be lined with plastic, and you need a pressure reduction inlet valve so you do not burst your cylinder. I would buy a small commercially made steel insulated high pressure storage cylinder holding about ten gallons of hot water. That should do several hot showers.