Super Sized Solar Thermal

hot_rod

I came into a pile of used 2X4 rectangular aluminum tube. So I need to come up with projects:)

I built a picnic table first.

Next, a solar collector the width of my shop roof, 28 feet.
It will have 4 separate absorber plates reverse returned. All piping inside the frame, two end connections.
4 pieces of tempered glass.

I may need to do a "solar raising" one weekend to get 'er up on the roof.

EBEBRATT-Ed

Love the table! Did you make the chairs too LOL.

Looks like you may need a crane to get the on the roof.

Larry Weingarten

How much are the individual panels going to weigh? Maybe four strong guys to tilt it with one end against the edge of the roof. Then, two guys on the roof, two on the ground with ladders. This might work if they like beer later.

Yours, Larry

Mad Dog_2

You've got Golden Hands!!  I'll send down the Mennonites I know from Penn Yan.  They work all day in the blazing sun..no breaks!  Mad Dog 🐕 

mvickers

Free Al?  And the cost of the Cu?  Did you paint it blk?

farmwi

Interested in how this project goes. Didn't understand the reverse turned?
Hope you have storage beyond normal DHW. Interested in how you connected the radiant fins to the cu tube.

Recently started testing some old copper panels, but they work, and a standard hot water heater tank isn't enough.

hot_rod

Here is how a reverse return piping looks. It attempts to present an equal flow path to all the absorbers so equal flow. This can be done with balance valves to eliminate that 3rd pipe. But solar temperatures, over 300° can be hard on valves.

Also shown is panel radiators in reverse return piping.

This is on my shop, so not much of a DHW load.

In my climate I calculate 1.5 gallon of storage per square foot of collector. So with my 70 sq. ft, I'll look for 100 gallons or so. probably two 50 gallon electric water heater tanks, or a 119 if I can a scratch and dent

This will be a pressurized drainback. So when there is no heat or DHW load the collectors just drain out, back to the storage tanks. So no issue with stagnation and flashing to steam in the collectors.

An example of a drainback piping. You leave a few inches of air space at the top of the tank. That air space becomes the expansion space, and also breaks the siphon when the pump shuts off and allows the collector to drain empty.

As long as the collector and outside piping is slopped to all drain to one end

hot_rod

mvickers said:

Free Al?  And the cost of the Cu?  Did you paint it blk?

I had 12 pieces of the ThermaFin kicking around, have to get 8 more  here
https://www.aetsolar.com/product/TFAP004

Copper tube and glass, some silver solder. Ill be into it around 800 bucks 

probably 12- 1500 bucks to buy a new 4x8 collector these days?

The new ThermaFin has a black coating, I will paint the stuff I have satin black

hot_rod

Pleased with the first run of the system, started with tank at around 70F, reached 172 by days end.

Larry Weingarten

Very nice! What ratio of gallons per square foot of collector did you end up with?

Yours, Larry

hot_rod

Larry Weingarten said:

Very nice! What ratio of gallons per square foot of collector did you end up with?

Yours, Larry

Not enough tank, I would like to have at least 1.5 gallon to square foot. So I end up with some high temperatures, some collector inefficiencies. It is mostly shop heat so I will use it pretty much as it is being generated at some point. I don't see storing much in only 50 gallons.

I'm always on the lookout for insulated storage vessels

hot_rod

I'm thinking about dumping my solar thermal directly to a cast radiator. I don't have enoug array square footage to try and heat the slab.

I keep the shop about 67F, but it is a little chilly by my rolling desk at the garage door. The radiator will be a nice warm radiant surface to sit next to.

Rubber tube connection so I can roll it around for cleaning the floor.

The collector flows about 4 gpm, getting over 150F still with shorter days and cooler outdoor temperatures.

I know threading into electric water heater elements holes will make some blood run cold I've had good luck doing it for 30 years now. 6 wraps of teflon tape. I'll run low pressure on the radiator to play it safe. The drop pipe on the upper nipple to get below the drainback pump down level.

Heat up an old chisel to melt away that fiber insulation around the connection to watch for leaks.

I need 15' of 3/4 Watts Onix to connect. Anybody?

Alan (California Radiant) Forbes

Those screenshots are hard to read, hot rod. I have to bar slide to get the whole picture and by the time I get to the right side, I've forgotten what was on the left side.

Larry Weingarten

Hi @hot_rod , Might automotive radiator hose work?

Yours, Larry

hot_rod

I did get some 3/4 MPH multi purpose hose from a nearby hose supplier. No O2 barrier, but.. Rated to 212°F

3/4 Onix is $1,100. for 200' roll!