solar panels

Not sure i follow?

Efficiency have been getting better for each year. Mono panels out there that are above 20%
 
There's even some panels that are closer to 24%, and in research there are forms that are about 28% and will be hitting production soon.

Then there's other chemistries that go beyond the 32% efficiency of what silicon can do max. There's one that is copper based that can do, if I remember correctly, 40%. But that's still in testing right now.

I'm wondering if 1958 is looking at recycled panels or old stock sales.
 
Im looking at new panels and there 39x65" and make 275-320 watts

20 years ago i got 3 panels for my dad, the where 12v and 75 or 100 watt, the size was like a 2x3 feet
 
1958greyhound said:
Im looking at new panels and there 39x65" and make 275-320 watts

20 years ago i got 3 panels for my dad, the where 12v and 75 or 100 watt, the size was like a 2x3 feet
Click to expand...

Yes and those panels you're looking at are over 30v. They pump out a ton of power. Make sure you get an inverter that can handle the higher voltage. They usually advertise them as 24v but the ones i have are about 37 volt.
 
And to add to AZ's comment, 39" = 3' 3", 65" = 5' 5". So they are about the same size.
 
Half the size but 1/3 the power.

It just shocked me when i found out the size and figured the sq footage for a 10kw install

If i did 31 panels.

I could do them 4x8 for 21 feet by 26 feet.
Sound like a perfect shade structure for the garden :)
 
Yeah those old panels was not more efficient. Todays panel are way better than 10 years ago.
 
Thats def true. I still have 10 in my garage that i dont have any space on any roof to put them on :)
 
1958greyhound said:
If i did 31 panels.

I could do them 4x8 for 21 feet by 26 feet.
Sound like a perfect shade structure for the garden :)
Click to expand...

Definitely! :) Then you can run copper tubing alongthe bottom of the panels to absorb heat (making the panels more efficient over the course of the day) and make hot water.
 
Korishan said:
1958greyhound said:
If i did 31 panels.

I could do them 4x8 for 21 feet by 26 feet.
Sound like a perfect shade structure for the garden :)
Click to expand...

Definitely! :) Then you can run copper tubing alongthe bottom of the panels to absorb heat (making the panels more efficient over the course of the day) and make hot water.
Click to expand...

I like this. I was wondering if any other schemes were out there to do this.

I saw a design of an aluminum sheet that had refrigerant lines embedded in it. It used a heat pump to suck the heat away and so it could work in cold climates.

It could also produce hotter water than circulating water. Condensation is an issue.

I also saw a french company had a system that used a blower and ducting to circulate air under the panel to cool it.
It took the air and exhausted in the summer, but it dumped it into the cold air returns of the house when the house required heatduring the day.

The challenge is to be cost effective. How do you do this on the cheap?
How do you get a system that controls condensation and also won't overheat in the summer.

Lots of little details to work out.

Thats the challenge...even in DIY power walls. The batteries are cheap, but the equipment to transfer the power into and out of the battery is where the cost is.

As we have all been discussing: It costs real money and time to mount the cells, solder, wire,mount, charge, balance, discharge, etc.
 
daromer said:
Thats def true. I still have 10 in my garage that i dont have any space on any roof to put them on :)
Click to expand...
I may be interested if you're selling them... pm possible?
 
Nah not selling them :) Not cheaper than you buy them anyways. In sweden you can get 260w for around 1300-1700SEK today. From 2nd hand non used to new ones.
 
For the backing on the panels you would use refrigerator water line. It's really cheap and can hold 100psi easy; not that you'd be running it that high.

Cut the flashing strip the length of the panel
Take a board with a single grove the length and be 1 about 1/8th larger than the pipe you choose. Lay the tube down on a hard surface straight; take the flashing and lay on the pipe; take the board and lay on top with the grove lined up with the pipe. Then take a hammer or rubber mallet and pound on the board to get the channel in the flashing.
Alternatively, you could lay the flashing on the board, pipe on the flashing, and use another board to hit the pipe in to the flashing. However, I think this method is taking a greater chance of damaging the tubing.

Then, when you have your flashing all channeled, lay the pipe in the channel, use a torch, and solder it all together. The tubing should stick out each end a few inches, or be long enough to loop into another flashing channel.
Use a high heat tolerant silicon sealant or epoxy to glue the flashing to the back of the panels; then squeeze as much as you can out and keep something heavy on it till it cures.
Connect all the tube ends together either in series or parallel.
I would run an anti-freeze mix through the tubing and then use a coil in a tank to do the heat exchanging.
You would also want to use some thermostats so that the water from the tank isn't hotter than the flashing and circulating when it's not needed.

And voila! Free Water Heat! :) You could even run the pump from the panels directly by using a cheap SLA charger as it can be set to run at 12V output and it wouldn't interfere with your other stuff.
 
It would work in the winter, too. So as long as it doesn't get "too" cold where you are.
 
Just south of phoenix, az
We get 2 weeks of cold about 34 deg then it warms back up.
This week its trying to break the 122 deg record.
 
Korishan said:
For the backing on the panels you would use refrigerator water line. It's really cheap and can hold 100psi easy; not that you'd be running it that high.

Cut the flashing strip the length of the panel
Take a board with a single grove the length and be 1 about 1/8th larger than the pipe you choose. Lay the tube down on a hard surface straight; take the flashing and lay on the pipe; take the board and lay on top with the grove lined up with the pipe. Then take a hammer or rubber mallet and pound on the board to get the channel in the flashing.
Alternatively, you could lay the flashing on the board, pipe on the flashing, and use another board to hit the pipe in to the flashing. However, I think this method is taking a greater chance of damaging the tubing.

Then, when you have your flashing all channeled, lay the pipe in the channel, use a torch, and solder it all together. The tubing should stick out each end a few inches, or be long enough to loop into another flashing channel.
Use a high heat tolerant silicon sealant or epoxy to glue the flashing to the back of the panels; then squeeze as much as you can out and keep something heavy on it till it cures.
Connect all the tube ends together either in series or parallel.
I would run an anti-freeze mix through the tubing and then use a coil in a tank to do the heat exchanging.
You would also want to use some thermostats so that the water from the tank isn't hotter than the flashing and circulating when it's not needed.

And voila! Free Water Heat! :) You could even run the pump from the panels directly by using a cheap SLA charger as it can be set to run at 12V output and it wouldn't interfere with your other stuff.
Click to expand...


Im planning to put about 40 - 50 panels on my roof. Thats a whole bunch of soldering. I am thinking about something not so elaborate with much fewer connections. The challengeof the antifreezesolar water system is that if it gets above 190F, the propylene glycol starts to break down. Also, the panels need to be cooled to a much lower temperature to produce more power than they would if you left them open and let air flow around them. What to do with the extra heat in the summer?

For the cost and complexityof all that, I could just add more panels and provide extra airflowaround them.

A swimming pool heater is maybe a better system to use what you are suggesting. if you design it with a drainback system, you avoid the freezing issue and don't have to deal with antifreeze. Like you said, you can put a separate pv panel on the roof to run the pump. In the peak of summer, it may be too hot in the pool for extra heating, but maybe some radiator could be rigged up to drain off the extra heat. i saw a video of some installer who did this with a wax based regulator valve to keep the system from overheating.


I'm going to design a system that uses extra PV to do all of my water heating electrically. Find out how much that costs and then try to design a panel cooling system that is cheaper than the extra PV.

I will plan to put in an extra hot water tank and treat it as a diversion tank to heat water when the batteries are full. This will give some good comparison.

- Egam
 
The drain back method would work just fine. Put a check valve in reverse at the top so it'll suck air back in when the pump shuts off.
Then if you do that, the best way for water to get back is to do a series connection as this will cause a syphon effect.

It is a little pricey. However, you don't have to use copper. It is the best to use, but not required. You could even use pex tubing.
Flashing it's all that expensive, but it's also not required; it just used to better wick the heat to the tubing

With the flow moving, I doubt the heat would reach 190F. But I wonder why it would break down at 190 as that's what's used in cars and they will get to 200 easy in the summer, esp with AC running.

You could also use a cooling pond instead. That is, not heating water, but using cooler water to cool the panels. You would just need to put a auto-fill floater in the pond/kiddie-pool.
 
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