# Help with solar hot water panels



## Gottabenutz (May 11, 2010)

I couldn't resist this yard sale find I stumbled upon. I was actually getting yard lights to hook up to solar panel for night time. Lady overheard and said she had some solar panels out back. They had used them (at previous home)to heat their pool water and suppliment their house hot water.
Long story short; I came home with 5 panels for $25. They are about 4 by 10 feet, with a connector for water at the top and bottom of the panel. They are very dark, but I can see tubes inside of the panel which is where water is supposed to run through to get hot. 
I'm looking for any basic info on setting up these. I didn't see a brand name tag on them yet; just some type of solar certification that is mostly rubbed off. I'm hoping I didn't waste $25 bucks on these. I'm sure I need some kind of pump to get the water into them once they are on the roof, and a way to get the hot water into the house. Any advice/suggestions/ websites is appreciated.


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## TnAndy (Sep 15, 2005)

Well, if they are copper panels ( the inlet and outlet stub should be copper fitting ), then you probably got a couple hundred bucks worth of copper for $25 if nothing else !

But assuming they don't leak, they are worth way more as heating panels.

Here's the basics on a solar water heating system.

There are two types:

1. Open loop, where you feed the water from the water heater tank directly to the panel. This system requires drain back so you don't keep water in the panels during freezing weather and damage them. More simple system, BUT you have to make sure the panels and all piping is properly tilted or sloped to allow positive drainage. You put a vacuum break type valve at the very top of the system so as you pump water up to the panels, it allows air to escape, then closes when water hits it, then opens again to allow air in as the system drains back.

2. Closed ( or sealed ) loop. In this type system, you circulate a water-antifreeze mixture, and you have to have a heat exchanger ( usually it's made in the water heater tank ), and the system stays full of the mix all the time.
More expensive system, since you have to use a mix....and the biggest expense is a tank with a heat exchanger.....they can get quite costly.

With EITHER system, you need the panels mounted ( usually roof, though it could be something else ), piping up and back, a pump, and a differential thermostat. The DT measures the heat at the panel, and the heat in the storage tank, then tells the pump to run or not depending on the delta T...the difference. Most of them can be set, so say the panel is 150 degrees, and the tank is 120, the pump runs. As the panels cool off, and the tank temp is higher, it shuts the pump off so you don't bleed the heat from storage back to the atmosphere.

I've studied them quite a bit, but never installed on. Getting ready to do one on my greenhouse, so in another season, I'll be able to report some actual experience. I plan to use a open loop system on this on.

Retrofitting a house for this is gonna be a PITA, in a lot of cases....you're gonna have to get the piping to the panels, which if your storage is in the basement, and the panels on a roof, can be something of a challenge to pull off. 

You've also got to match the pump size ( volume/hp ) to the system....the amount of flow you want, the volume of the whole system, head distance, etc.

The storage has to be considered.....most water heaters would not be big enough to handle 5 panels ( that was for a swimming pool....LOT more water to work with ), plus most of them don't have a handy extra set of ports to run the solar feed in/out.

You got the panels dirt cheap ( GOOD THING ), but my guess is you're still looking at close to couple grand for storage, pump, piping, DT, wiring, etc.....maybe less if you can use a garage roof, and your storage is right below....that would sure simplify things.

BEST thing you can do is buy a good book on solar water heating and how to install ( I have no recommendations ), and study this a lot more.

Good luck !


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## woodsy (Oct 13, 2008)

Gary's website has a lot of info on DIY solar water projects. 

Build it solar

You will need to do some homework to determine what type system (drainback or closed loop) will suit your needs best.

I built most all of my system from scratch using Gary's website .

Good luck and welcome to the club, its pretty cool to have economical hot water !

You may not need all of those panels, depending on your family size.

You will need to somehow test those panels for leaks before installing any.


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## redwall (Mar 10, 2007)

she said pool right if so it could have a lot of chemicals in it from the pool water a friend of mine had one and the pool pump ran the water through the system. and back out into the pool it was an open system


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## SolarGary (Sep 8, 2005)

Hi,
If those are glazed solar heating panels with copper piping inside, that's about $5000 worth of panels for $100 -- not so bad 

Can you find anything that indicates who made them, or read any more off the certification label? If its an SRCC certification label, that's a good thing in itself in that it means they went through the SRCC certification, which is pretty tough.
Can you see how large in diameter the manifolds are? Are they copper?

200 sqft of collector is enough to do domestic water heating as well as some space heating. If you look here:
http://www.builditsolar.com/Projects/SpaceHeating/Space_Heating.htm#ActiveWater
The first three systems listed might work out for you -- or at least be a place to start looking. 

If they were used for pool heating, any chemicals left in them should not be a problem as the water that circulates through the collectors has no contact with the potable hot water you make in most systems.

Woodsy makes a good point about pressure testing them.
http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm#Maintenance

I think you got a heck of a bargain!

Edit: forgot to mention that the Home Power articles listed near the top of this page:
http://www.builditsolar.com/Projects/WaterHeating/water_heating.htm
are a really good place to start learning what goes into these systems -- you can get an online subscription to Home Power for 10 bucks, and it gives you access to past articles. The Drainback one by Marken and Olsen is very good.



Gary


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