How long should a Solar Hot Water panel last?

jeant

From my experience with a certain brand of panel I was getting 15 to 18 years. What I have seen lately is 10 years. Replacement can be pretty expensive. Does anyone else have an opinion about cost to replace vs savings on fuel or electricity?

Jamie Hall

Interesting question. I hope others respond. For me, I would be astounded if there weren't a very wide range -- what is your cover material (glass? What kind? How thick? Protected from impact?) what is your trapping material (copper? some kind of plastic? Basalt with flow over? Clay tile? Ductile Iron?). I can envision answers from two years to two hundred...

hot_rod

What fails? The copper inside, the glass, case or gasket leaks?

By far the main cause of the copper tube failure is lack of fluid maintenance in glycol systems. The system needs to be cleaned before putting in any fluid. With glycol the Ph is critical and should be tested yearly and boosted or replaced. Use only the high temperature, solar specific glycols.

Any collector that spends a lot of time in stagnation conditions, in a closed loop glycol system is probably the most apt to have a shorter life.

I don't like seeing ST on vacation homes for example, not enough use, lots of stagnation time.

Depending on the brand, I have noticed a thinner gauge copper tube being used. Seems the industry started out with type L, then M, not it looks like fin tube grade of tube in some. Cost and weight reduction.

I have a few 30 year old Revere Copper collectors on my property. The copper gauge is more like a type K.

Plain water drainbacks seem to have the longest life expectancy, often outliving the roofing materials they are mounted on.

Ironman

@hot_rod,
What's the life expectancy for Caleffi panels in a closed loop with good maintenance?

hot_rod

Ironman said:

@hot_rod,
What's the life expectancy for Caleffi panels in a closed loop with good maintenance?

I would expect 20 years or more. They come with a 10 year warranty as do most of the US built collectors.

michael_34

jeant said:

From my experience with a certain brand of panel I was getting 15 to 18 years. What I have seen lately is 10 years. Replacement can be pretty expensive. Does anyone else have an opinion about cost to replace vs savings on fuel or electricity?

What brand is only lasting ten years?

spd

Hello! I maintain 5 systems over 25 years old. 3 of these have never had an panel fail. The panels last as long as any copper would, decades and decades. Leaks, air and bad glycol are the main culprits but the only way the panel itselfwould fail are freezing from a weak glycol mix or internal breaking from extreeeme overpressure which is the fault of the expansion tank. It is also important to check the ACIDITY of the glycol with PH paper as well as glycol content at least every three years and adhere to the 5 year glycol change maintenance proceedure.

COST:
Replace any broken piping/control/pump/expansion/fluid components using only a very excellent hydronic technician. Don't cheap on parts or glycol or time! It is worth it and not more than maintaining a boiler. However, if for some weird reason, your COLLECTORS are physically broken, you might as well throw in the towel and try to practice better upkeep on your next try with solar thermal!

Maintenance is worth it. Think of it as your car. Or boiler.

Jessica

Rmechanical

There are some poorly made panels out there. I have had good, solid, long life systems by using Sun Earth paneles from California - installed mostly with Drain-Back design and some glycol with Steam-back design. In Colorado we reuse 30 year old panels in good shape and there are lots of them out there. Drain-back, Glycol or Silicon oil. What Hot Rod said about glycol stagnation and becoming acidic - is the biggest problem with an antifreeze Glycol installed system. Please consider upgrading the freeze protection to drain-back or steam-back. see this discussion from "The Wall"
https://forum.heatinghelp.com/discussion/133064/steamback-system-design

crash105

I have a home in Portland, OR. It has a Grumman Sunstream glycol system. The water heater is a recently replaced item. A Richmond water heater with electric heating as back up. 80gal. The problem I am having is that the system will cycle the water heater water through the heat exchanger before the glycol side is up to temp, thus cooling my water. it has a Heliotrope controller. I think the system was installed in the late 80's or 90's. Any suggestions on where to start and how to trouble shoot the problem ?
Dave

John Ruhnke

A client of mine had a perfectly fine and functioning solar thermal system on his house that was from the 70's. The panel's pump and piping were all original. It was 40 years old at the time he asked me over to take a look at it. He had a tank with heat exchanger but I think it was changed once about 20 years ago. That was working great. So he needed a new roof. He wanted me to price the job to remove the old panel's and reinstall them onto the new roof after it was completed. I gave him two prices. He had a three panel system. The first price was to do what he said, remove and reinstall. The second price was to remove the old panels and install three brand new panels. The price to install new panels included a state rebate. So the new panels ended up the cheaper price because of the rebate. He gave me the panels for free!!

So the three panels sat in my driveway for 6 months. Nobody wanted them because the rebate didn't cover installed used panels. Finally a carpenter that I was working with, who lived up north came over and took them. He wanted them for his house and they didn't have a rebate. I gave them to him for free.

So Solar Thermal can last 40 years or more!!!

hot_rod

The quality of the construction, gauge of metals, fluid maintenance all play into life expectancy. I would say pin-holing from aggressive glycol is a common failure point.

I see 30 year old collectors still in working condition.
Here is one of a few 1970 vintage Revere collectors I still run.

Unique absorber design and very heavy gauge copper.