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Some final words

The end of an era. Mission accomplished?

It is with regret that I have made the decision that Solar Designs will cease installing new systems. It was interesting, it was fun, but every good thing has to come to an end.

When Solar Designs started in early 2008 it was out of the need for good value grid connected systems. Back then the industry was very small and prices were high. Indeed, in 2007 I wanted to get a system for my own house and was shocked by some of the quotes I received. That made me take matters into my own hands: I completed the accreditation requirements and started Solar Designs.

Now at the end of 2010, some 200 installations later, the PV industry has changed tremendously. There are literally hundreds of companies with thousands of accredited installers. Lack of competition is no longer a problem. In that respect the mission is accomplished. Solar Designs is no longer needed to bring prices down. Time to take the burden off my own back and to stop lugging panels around, I'm not getting younger.

Unfortunately a trend has emerged that makes it tougher than ever for customers to find a good value system. Large parts of the industry now install panels and inverters from manufacturers that have a very limited track record of just a few years. Most of those components come from China and the manufacturers have only just started making them. While they may last there is no assurance that they will, many are expected to fail prematurely. For a 20 year investment that is not good enough in my view.

At the same time big name installers with huge advertising budgets swamp letterboxes and make unsolicited calls. While the names are big so are their margins. The components they use are usually only average, but prices are top of the range, capitalising on the big name. Often high pressure sales tactics coerce home owners into signing up on the spot, taking away any chance to shop around.

Those two developments are very worrying. They both have the potential to damage this very important industry in the long run. Components that fail after a few years, with manufacturers no longer around to honour their warranty, will mean a waste of thousands of dollars not only of customers but also of taxpayers money. Paying thousands more for a system from a big name company that does not perform any better than that of your neighbours can be just as discouraging.

While I am actively competing in the market there is nothing I can do about it. Why would anyone believe me more than the other guy? A marketing exaggeration by a slick sales rep is easy to make and hard to disprove. The truth is usually complicated, sometimes it involves lengthy calculations. Which customer has the time to get familiar with all the technical terms and to look into that level of detail?

Being no longer involved in installations might add to my credibility. I am not completely unbiased, experiences during the last few years have of course left impressions with me. I have not worked with all the available materials, so there might be some good products that I know nothing of. That said: I have spent lots of time researching materials and it would be a waste to just let that knowledge disappear. So here is my parting present, some advice, to the best of my ability:

Some advice for people thinking about PV

The main components in a PV system are panels and inverter, they deserve very close scrutiny. Wiring and mounting frame are important too, but so is installation quality, those last all come down to the individual installer.


In general: the rated output in W is the number to compare. Systems from different manufacturers will produce very similar amounts of power if they have the same rated number of W. Variations in temperature performance might make a small difference of around 2-3%, hardly enough to worry given all the other losses in a system (rating tolerance, panel mismatch, wire losses, inverter efficiency). Output estimates given to you by sales reps can be more or less optimistic, sometimes outright misleading. Compare apples with apples: compare rated W with rated W.

  • German brands: Bosch, Schott, SolarWorld all are excellent quality. SolarWorld pricing especially is very attractive (as of Nov 2010). Bosch, made in Germany with an extra long warranty, are worth their slightly higher price as well.
  • US brands: SunPower E19 panels are a top of the range product, but current prices are somewhat prohibitive unless you live in the Solar Cities area of Perth's Eastern suburbs where discounts apply. The E13 panels (Serengeti) are re-branded and actually made by a different manufacturer, not my can of worms.
  • Chinese brands: SunTech are the biggest manufacturer of crystalline panels in the world. If I had to pick a Chinese made module they would be my first choice by some margin. Trina, Yingli and Solarfun all have been around for quite a while and are major companies. Unknown Chinese brands are just that, unknown. Their products may be good or they may not be good. If you save at least $500 per kW they could be worth a punt for people who like risk, but I would not do that for my own home.
  • Japanese brands have a good reputation but I have no practical experience with them. Kaneka with their thin film panels use lots of roof space. If you want to cover most of your roof to shade it and have no plans to use that wasted roof space for other things later on (PV expansion, solar hot water, pool heater), they should work fine. But be wary of exaggerated output promises, compare rated W with rated W.
A word about panel warranties:
Yes, warranties are important. But they are only as good as the company that gives them to you. If an unknown manufacturer disappears and the importer can't be found, your manufacturer's warranty is not worth the paper it is printed on.
Most panels have two different warranties, an output warranty, usually 25 years, that promises a certain minimum output from the solar cells. And a product warranty, in most cases 5 years, sometimes 10, sometimes just 1 or 2 years. The product warranty covers the whole panel. The output warranty is of very little use if the panel is no longer in working order i.e. after the back has de-laminated or water has entered the junction box.


SMA are the clear market leader with about 40% market share. Their Sunny Boys are made in Germany and built to last. I have not had a single warranty case from the over 100 units I installed. Compare that to 6 repairs out of 36 installations with another well know European inverter brand.
Chinese inverters companies have a very limited track record, most only a year or two. Are a few hundred dollars upfront saving worth that risk? Prices from SMA are quite competitive, very similar to other European and US brands, I see no need to compromise.
There was a shortage of good quality inverters earlier this year (2010). Many people were impatient and chose whatever was available on short notice. By now production has caught up with demand, one less reason to pick anything but the best.
In the interest of full disclosure: I do hold shares in SMA because I really trust their products and expect that quality will win out in the long run.


The best inverter and the best panels are of little use if they are not matched to form a well performing system. A common mistake is to ignore variations in voltage at different temperatures. Each inverter has a limited input voltage range:
  • It needs a minimum voltage to operate panels at the maximum power point. On hot days panels produce less power and run on a lower voltage than rated in the data sheet. If that is not considered during system design the panels will run very inefficiently on a hot sunny day.
  • The inverter also has an absolute maximum voltage that can not be exceeded without voiding the warranty and endangering the inverter. On cold mornings when the system is just about to start up the voltage produced by the panels is the highest.
  • Those two factors combine and leave only a very limited range of possible combinations between any given panel and inverter. Different panels use slightly different technologies and cell layouts, resulting in different voltages.
Ask your installer to verify their configuration. For SMA inverters the software Sunny Design does that very efficiently. You can download it from the manufacturer's website for free. To play it safe select '250V' as the grid voltage, we get that here in WA all the time. If you are away from the coast and don't get the early sea breezes the temperature window should be increased to 75 degrees.


The DC side (power coming from the panels to the inverter) will often run at a higher voltage than AC. If a wiring fault causes arcing in a DC system that is seriously dangerous. That's why the current standard recommends the use of single core double insulated wires. Ask your installer if he follows the recommendation or tries to save a few dollars by using TPS.

Mounting Frame:

Several brands offer good off the shelf solutions. It is important that enough supports are used. For tile roofs some framing systems require drilling holes in tiles, I don't think that is a good idea. Silicone will seal it for now, but for 20+ years, really?

Offer for assistance

If the above is not enough information and you have a hard time deciding between different quotes you can send me an email and ask for my opinion.

Please note: this is a free service, I can not guarantee that I will reply or how quickly I will reply. If one of the companies that quoted for you forces you to make a quick decision, rule them out. In almost all cases the only reason to make a quick decision is to lock your business in for them, taking away your right to shop around.

By sending information to me you agree that I may keep the information to build up a comparison database that will allow me to see 'what is out there in the market'. At a later stage I might or might not publish summaries of this information. If I publish I will of course ensure that all personally identifiable information is removed.

What I need to know to evaluate a quote is:
  • Date of the quote, expiry date if one was given
  • Panels:
    • number of panels
    • rating in W per panel
    • brand name
    • model number
  • Inverter:
    • brand name
    • model number
  • Roof:
    • single storey / double storey
    • tile / metal
    • suburb you live in
  • Price:
    • out of pocket cost for fully installed system (excluding metering cost, but after government subsidies, Solar Credits, etc)
    • total cost of system before discounts and subsidies
  • Expected annual power production as given in quote

Good bye and thanks to all!

All right, that's it. Thanks to all customers for their trust, all suppliers for their support, all electricians for the good jobs they did and all government agencies for keeping up the challenge to run a viable business in an environment with constantly changing goal posts.


p.s.: customers who already signed up will of course get their systems installed as scheduled over the next few months, no worries I am not running away with your deposits

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