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).

A really good exsample of why solar panels must be designed for servicing

These panels are of unknown make and are from 10-15 yrs old. It has heavily corroded copper surfaces and you can see the leaking hot water from the pipe in the 3rd photo, leaking several liters of hot water per hour (Bottom right of picture) and probably for more than a few years. You will also note the absence of any lagging on the pipes.

Points: - Fortunately, this is of a thick copper design. It can presumably be stripped, cleaned and restored to as good as new.
- Where different metals meet (Such as galvanised steel fittings on copper pipe), corrosion is inevitable.

- No air vents to allow moisture to escape, so this needs to be recitfied and the glazing seals replaced.




These panels show that it may be misleading to give the impression that any solar panels can be "set and forget" other than needing the occasional wash. Few structures can be expected to last 20 years exposed on a rooftop for 20 years without requiring a decent service now and then. Design should be such that panels can be conveniently dismantled and serviced as required.

What is also shown here is the corrosion that is likely to occur when different metals are in contact, setting up galvanic corrosion. This includes metal on metal contact with a metal roof as well as differing plumbing fittings. Once started, the only practical remedy is full replacement of the corroding parts.

Corroding solar water heating panels "A serious failure"

"Hi Gary,
I just discovered your web-site over the the weekend and decided to take a look at my solar panel.
Thanks for the publicity on the issue and advice!
Like many others I may have been oblivious to what I consider a serious failure."
Anon.
_________________________
Gary Moller comments:
If you know of people who have solar water heating panels installed please urge them to carry out their own inspection independent of who did the installation. Solar panels are the perfect product - out of sight - out of mind until well out of the warranty period.

Notes about these Wellington panels:

• Installed about 16 months ago with a required payback period of over 10yrs
• All of the panel is seriously faded or corroded
• No building consent obtained by the installer
• Cost of a building consent would have been about $50: Is now about $700 to get a Certificate of Acceptance
• The same problems with rusty solar water heating panels exists in Australia

Refer here for more information about rusty solar panels.