solar water heater

2x2 ft is not terribly big, but your van isn't too big either. Too much plumbing, seems to me.

I used solar showers on two occasions: in Hawaii in November and in Mexico in February, and didn't like it.
In Hawaii there were trees on the camp, so it was never hot.
In Mexico it was out in the open and the weather was mostly sunny, and there was a choice of solar shower and regular propane shower. Since showers were free, it made sense saving own propane. I found myself using solar shower only when the propane one was taken by somebody else. It was never hot when I needed it, neither in the morning nor in the evening. Maybe in summer I would've used it more often in daytime, but then, in summer I don't need a hot shower too much - it's too hot out there as it is.

Looks like a really interesting pre-heat for the water heater. I have considered similar systems at the house. It's obvious of course this would not be the only source of water heating because of lack of sun over night and poor solar production days.

Jim

Hi Almot,

The collector holds only 2.7 ounces (by weight) of water. It is 24" X 25.25" X 2.125". Total panel weight is 10.6 lbs. Collector temperature is 203 F (maximum??).

Almot wrote:
And again, these 6 gallons on the roof... You can't leave it there, you have to drain it every time when you move. 50 pounds of water sloshing back and forth when you drive - no, thanks.

Also, how big is this thing?

Hi,

Here is a response in regards to freezing from BHA solar:

"Freeze Protection

Our Solar Water Heater Panels are designed to connect directly to your water system, so they contain water. Since they are installed outside they are also subject to freezing temperatures. When the water in the panels freezes it immediately expands by 9%, and if it has nowhere to expand to it will actually stretch and ultimately destroy the tubing in the panels.

If you are using our panels in an area where freezing temperatures are rarely encountered (once a year or less on average) and if you are using PEX tubing to connect the panels to each other there is no need for a freeze protection system. The ice will expand out of the panels and stretch the PEX tubing somewhat.

If you have more frequent freezes one of the following freeze protection systems must be used:

Freeze Valve – A freeze valve is typically installed near the highest point in the solar installation. It is a simple and reliable device that releases small amounts of water when temperatures approach freezing. This way the panels and all the plumbing are kept ice free by allowing warmer water from the inside to slowly flow through the panels.

Drainback Tank – This is a device that is installed inside in the water circuit. When the pump shuts off in the afternoon, the water from the panels and plumbing outside is allowed to drain out, and the outside components fill with air from the drainback tank. This type of system has the advantage of not draining any water, but is more complex and requires a larger capacity pump to re-fill the panels with water when the sun shines again the next morning.

Water Circulating System – In this type of system a very slow circulation of water from inside the building through the panels is maintained during periods of freezing. This solution requires the pump to operate at a reduced speed when freezing conditions are sensed, so a supply of electricity at night is required. Because a failure of this electric supply will cause immediate freezing of the system it is not an approved method of freeze protection.

Manual Drain – You can de-activate the system during the period of frost by manually draining the water out, especially if at your location the freezing period is also mostly cloudy, or if the sun angle is very low, because the
efficiency of the system is low during these conditions anyway."

I've written back to as the price for a drain down system.

BTW I'm harvesting 219 watts @ 1:00 p.m. (16 amps BFL)

HiTech wrote:
The solar powered pump is an elegant solution for solar water heat since it is only pumping when there is enough sun to heat water.

It is simple and it is not going to work. I'm Ok using 80F water, and so are many other people. And it can get that warm under cloudy skies in summer. But if the pump won't work, then I can't use this water.

The whole idea is only a partial solution. No hot water in the morning when you need it the most. Not much hot water in the evening if you are wintering down South, when it's dark and cool after 6 pm but you still need some hot water for kitchen and washroom on that day.

And again, these 6 gallons on the roof... You can't leave it there, you have to drain it every time when you move. 50 pounds of water sloshing back and forth when you drive - no, thanks.

Also, how big is this thing? Like a 100W solar panel, 200W? For eco-minded folks there is barely enough roof real estate for solar panels. Paper plates or not, but propane heater really looks better than this thing.
In a shore cabin this heater makes some sense, yes.

HiTech wrote:
The solar powered pump is an elegant solution for solar water heat since it is only pumping when there is enough sun to heat water. It might be better if it charged a capacitor to run the pump ( for better time phasing to the availability of hot water), but generally it is simple and clever.

I think the idea of running some small tubing on the back of solar panels to draw heat away from photovoltaics is also an extremely elegant solution. It would increase power production, even when hot water is not needed.

Jim

Excellent idea. I've seen dual purpose panels on CL but the hot water part leaked so they were selling them off cheap.

The solar powered pump is an elegant solution for solar water heat since it is only pumping when there is enough sun to heat water. It might be better if it charged a capacitor to run the pump ( for better time phasing to the availability of hot water), but generally it is simple and clever.

I think the idea of running some small tubing on the back of solar panels to draw heat away from photovoltaics is also an extremely elegant solution. It would increase power production, even when hot water is not needed.

Jim

I decided that metric would be easier if I did everything in kilopascals. I would have done the same with ergs, but never understood those things either. Kind of like watts. Strangely enough, neither ergs nor kilopascals has ever come up in normal conversation, so it is working out perfectly.

Considering how little education our government employees have, I wouldn't be surprised if somebody reported weight - or rather, mass - in Pascals.

I'm sure metric has its virtues. I do remember an LOL at the local hardware store guy who said he now had "metric yardsticks' for sale.

You do know that Napoleon screwed up the kilometre because the Earth is not spherical? The nautical mile, ISTR, is taken at one minute of latitude at 48N. The Earth is fatter to the South (pear shaped) so you have to pick somewhere and go with that.

Solar must be different "Down Under"