Proposals received - Thoughts?

Re: Proposals received - Thoughts?

If you find a reputable dealer / supplier / make, a thought to consider is to purchase B-visuals. B-visuals are the exact same specs as the A-grade panels, but may have a visual defect, resulting in reduced cost per watt, most of the times with a warranty.

BUT!!! One of Ben Franklin’s famous sayings is that “The bitterness of poor quality remains long after the sweetness of low price is forgotten.” so be careful.


In SA, from a reputable dealer, Sunmodule Protect SW 245 – 260 poly, has been tried and tested, by themselves, over many years. SunPower panels sells for +-R12.75 per watt ($1.21), and their B-visuals sell for +-R8.00 per watt ($0.76). However, they are looking at a limited warranty in some cases.

This is what I am told about SunPower panels:
Performance ratio takes into account the amount of solar electricity produced by the device in relation to the solar irradiance available and the efficiency of the module under standard test conditions (STC). A performance ratio of 100 percent would mean that a module with a 15-percent conversion efficiency, for example, produced 150 kWh under 1,000 kWh/m² of solar irradiance in a year. Hence, knowing these values allows for a direct comparison between modules that use different cell technologies and have different degrees of efficiency. The best modules had performance ratios close to (or in the case of the top-ranked device, above) 90 percent. Performance ratios under 85 percent are considered relatively poor. Further improvements to module technology will most likely cause these values to increase in future. Eventually, it is expected that modules will have performance ratios reaching nearly 100 percent. Of course the strength of the panels and the age and longevity matters more since a panel with a 90% performance ratio that has double the life of a panel with a 95% ratio is obviously a better choice.

The SolarWolrd old technology 210Wp panel, the Sunmodule Plus SW 210 poly was manufactured in 2004 and installed in 2006 and offered 213.21Wp when it was new, in contrast with the ReneSola it provided more power than was paid for. Moreover, it provided 212.6Wp in 2009 (degradation was thus about 0.286% instead of the allowable 3% on the guarantee document) while today it is still providing 212.2Wp more than 8 years later. In 2012 it offered a Performance Ratio of 90.7 and produced 120.5kWh/kW, the 245Wp SolarWorld panel which went into the test with the ReneSola panel in 2012 has a Performance ratio of 91.8, higher than ReneSola

The latest SolarWorld ‘Protect’ range of panels are much more stable than the normal SolarWorld panels. It is a unique 30-year linear guarantee, a max 0,35% p.a. And a guaranteed 90% after 21 years, and 86,85% after 30 years.

Over the extra ten to fifteen year life that this panel will produce compared to the Chinese options, as well as the lower degradation over that time, it is worth the extra money.

Re: Proposals received - Thoughts?

I like PowerOne and they have a good product, and are made here in Arizona, but are currently having problems with their arc-fault circuit which you do not want, and they were recently bought out by ABB so are going through the throes of that. I'm holding off spec'ing and PowerOne for a while.