Wednesday, November 12, 2008

Gary Moller's experience with rusting, corroding, fading solar water heating panels

This Sola60 panel (above) on our house looks impressive doesn't it? This is saving our family money on water heating and it is great for the environment. We are responsible citizens in this clean and green land. That was what we thought.
We noticed a steady drop off of peak water temperatures over a one year period, so I decided to investigate.

Here is another view:

There is extensive corrosion of the collector's absorber surfaces of this year old panel and what appears to be bleaching so that the surface looks grey-blue.

Here are the replacement panels that were supplied to us under warranty:

They are very smart looking. Now, here they are after a year:

These panels are bleached and have extensive corrosion (looks like sprinkled talcum powder) of the collector surface. And they now look kind of grey-blue which is not the best colour for absorbing solar heat.

Thankfully, they were replaced under warranty.
Here are the replacement ones seven months after being installed. Look carefully:

They are corroding again and we currently (30/11/2206) have a request with Sola60 to remove the system entirely from our roof because the warranty has not long to run and plenty of failed attempts have been had at resolving the problem. They were removed 24 January 2007.
Is there a problem?
The first clue that something may be amiss comes from the Branz report of Research Commissions:
"BRANZ Ltd identified that one of the biggest uncertainties in the cost/benefit analysis of solar water heating systems is the lack of reliable field data for system performances. Anecdotal evidence suggests that most existing systems fall significantly short of the calculated values used during the system design."
Could this shortfall be due to corrosion of the collectors?

How big is the problem? This is the question that I set out to answer by spending a few weeks trying to locate solar water heating systems in Central and South Wellington. This was not an easy exercise. I found several (Ours included).


Anonymous said...

Gee Whiz, I've been installing solar panels for over two decades here in the evil empire (that'd be the USA) and haven't seen any kind of problems like these. We use all copper, chrome oxide coated collectors. The panels on my house are 25 years old. My system made 120 gallons of 115 degree Farenheight (46 C) hot water starting from 50 F (10 C) yesterday (25/1/08 or 1/25/08). This is with 80 square feet of collectors. The ouside temperature did not go over freezing and I'm at latitude 42 N. Something is seriously wrong with the products being used in NZ if they can't make hot water. Maybe if we can help the kiwis get their solar hot water program together they can help us create a democracy!
Conrad Geyser
Cotuit Solar

Conrad Geyser
Cotuit Solar
P.O. Box 89
Cotuit, MA 02635
fax) 508-428-8441

Anonymous said...

How are you posting in the future?

Gary Moller said...

Please go to the "Blog" tab in the upper right hand column of this page. It is the blog section that is going to have most of the activity from now on. This page is more static.

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Solar Heat Exchange Manufacturing said...

Is this a closed loop system? I would assume not, since you're experiencing some serious corrosion inside your collectors at a rapid pace. You should definitely check out our Simple Drainback System. Unlike pressurized glycol systems, our system runs on water in a closed loop. It is closed off from the air so there won’t be a need to refill the tank. The solar water impurities that would cause corrosion in the solar loop will be “cooked” and settled out when the system first runs. Our tanks are warranted for ten years and their expected life is over 25 years.

Check it out -

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solar water said...

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