Wednesday, July 11, 2007

Some notes and commentrary about what I think is going on

Comments about what might be going on here:


  1. The following pages do not purport to be an authoritative study by a qualified expert. This site does not endorse or favour any product over another. Solar water heating installations are presented as they were found. They are in no particular order and may only represent those brands that have sold the most in a region.
  2. Any information is that from one interested consumer being passed to another. Anybody may offer corrections and add further information by the comments function of this blog, or by writing direct to the owner.
  3. Modern solar water heating systems are very efficient and a technology that is sensible to embrace. However; they must work at close to peak, trouble-free seasonal efficiency year after year for 15-20 years to provide payback on the investment.
  4. The difficulty for the consumer is on deciding which make and model will go the distance when most of the modern systems on NZ roofs are only a few years old. These web pages and the feedback from readers via the blog comments may assist the consumer wiht making an informed choice.
  5. Even if a system is replaced under an extended warranty, this runs counter to "green" sentiments by creating expensive landfill materials.
  6. This page was first loaded November 26, 2006 and is updated regularly. By the date of this page's latest update (25 Feb 2007) over thirty faulty setups have been identified and this number grows by the day.

Quick Summary

  • Our family home had solar water heating for just over four years.
  • In that time, we had the collector panels replaced three times.
  • The third set has visibly corroded in just seven months and needed replacement.
  • Our warranty was due to run out out in less than a year and the company (Sola60) refused to warranty the replacement panels beyond that time.
  • We then sought a refund and removal of the system. Sola60 refused.
  • Our only option was to take the matter to a Disputes Tribunal hearing.
  • Dissatisfied with the Tribunal option, I decided to see if other consumers had similar problems.
  • Of those solar water heating panels that were able to be examined, all Solahart and all but one of the Sola60 panels were visibly corroding meaning that in excess of 80% of the total of all flat panel systems older than one year showed discoloration. Photos of many of these are published on this website to give consumers a good idea of the extent of the problem and to know what to look for.
  • The problem is not restricted to Sola60 or Solahart as is evident from the photos on this website.
  • None of the householders contacted were aware of the problem.
  • The same pattern of discoloration, whatever the cause may be, is reported and documented for other parts of New Zealand and similar results are found in Australia.
  • Many of the installations, including ours, did not have the required building consents despite this being a requirement in most cases if not all. According to our insurance company our house insurance has been compromised for the last four years.
  • Many of the installations lacked the required insulation lagging on pipes as is required for peak performance.
  • Many were poorly sited and improperly angled to the sun and thus compromised in terms of performance.
  • As a result of this website going live in November 2007, we have now received a refund and the panels on our roof have been removed.
  • This website is being maintained as an information resource for the consumer.

While Although I am not an expert on these matters, I have studied physics and chemistry at tertiary level and I probably have a better than average technical knowledge. One can not assume that what works well in the relatively hot, dry conditions of continental Australia, the USA or the Middle East can be transferred to New Zealand's climatic conditions.. New Zealand is a long and narrow country. It is typically very windy with lots of rain and humid coastal air that is salt laden (Since writing this, the same patterns have been documented in Australia).

Solar Solar water heating panels are intentionally sited in exposed locations, typically on the top of buildings. They are therefore exposed to the worst local conditions of heat, cold, wind and water. In Wellington solar panels are subjected to salt-laden rain that is horizontally driven by wind gusts that can exceed 160km/hr. Unless the panel is exceptionally well sealed and built from corrosion-resistant materials, it is inevitable that water will get inside and materials will eventually degrade (It should be noted that similar problems are seen in central North Island locations that are well away from the ocean).

Another factor that may be at work is the circadian expansion and contraction of the inner air space. Heated air is forced out during the day; then cool moist air is sucked back in during the night to condense on the glass and collector surfaces. The next day the moisture is evaporated, leaving a slight salt deposit that steadily builds over time. If you look carefully at the first photo of the Solahart panel you can see what appears to be salt streaking left by condensation on the innerside of the glass. The same can be seen on the collectors of the Sola60 panels

Once the metal is wet and with a buildup of salt and the cyclical application of heat and cold the conditions are ripe for some exciting chemistry: namely corrosion - the conversion of metal into powdery whitish metal salt crystals. Corrosion is also rampant where Galvanic processes are at work. Galvanising happens where different metals, like copper and aluminium, aided by moisture and salt, are able to exchange electrons in a redox reaction like what happens between the cathode and anode partitions of a standard battery. Once these destructive processes have begun, the solar panel is probably doomed.

Fading may be due to the black coating surface on the collector being of poor resistance and even too thin to resist the baking under high UV sunlight.

These corrosive processes are very gradual and may go unnoticed until after the warranty has run out. From my survey of Wellington and other parts of New Zealand, this would appear to be what is happening: Not a single householder that I contacted had any idea of what was happening. For those with patternised glass panels, being able to see what is happening underneath is especially difficult.

Access problems means that many panels are inaccessible for householders; particularly the elderly. In some cases, scaffolding, ropes and harnesses are necessary to safely gain access to rooftop panels.
The general inaccessibility of the panels, plus the very gradual deterioration in heat absorption is such that few people will notice. This gradual deterioration is further hidden by the daily and seasonal fluctuations of sunlight (In Wellington we often get all four seasons in a week!).

Power bills fluctuate for all kinds of reasons and the electric booster heater on a single tank system may hide the deterioration by quietly working a little harder as the years pass. The consequent increase in power bills is understandably attributed fully to price increases. We insisted on a double tank setup which was fortunate. We have one tank that is entirely solar heated. It feeds into another tank which is then boosted before being used by the household. We are therefore able to closely monitor the daily solar performance as the months and years go by without being confused by power bills.

Which system is best for New Zealand conditions?
Let us find out for ourselves. If you have a solar water heating system; especially if it is more than four or five years old and still in perfect working condition, I want to hear from you. Write in about your system. You must include photographic evidence and documentation of age that I can publish and include your contact details (Contact details will be kept confidential).


Unless you really know what you are doing, you must stay off your roof. Please read the safety information on this website

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