An expert review of SolarWorld solar panels
Key Advantages of SolarWorld Solar Panels
Solarworld are a German company that has had a significant solar panel manufacturing presence in America for some time.
Their panels are good but not the very best in terms of efficiency or high temperature performance. The key reasons that they make our top five is that;
- They are American made
- They have a very good network of local installers around America
- They have a reputation for very good quality and invest a lot in their brand
Key Disadvantages of SolarWorld Solar Panels
My biggest concern about SolarWorld is that they are completely reliant on the solar industry because all they do is make solar panels. This makes them financially vulnerable to sudden downturns in the solar market like the one we saw in the second half of 2016.
They have struggled to get to profitability and so it is hard to say with any certainty that they will be around in 10 or 20 years time, although admittedly with the pace of change in the industry, it difficult in general to predict whether any particular company will be still around and making solar panels in 20 years. This is one of the things that makes the purchase of solar panels very different from a purchase of most other consumer goods. There are very few things you buy that come with a 25 year warranty and so when buying such a product your view on the likely future of the company is important because the warranty is an important part of what you are paying for.
SolarWorld Solar Panels Summary
The SolarWorld Sunmodule series of panels are a good quality solar panel with a top efficiency on their SW 300 watt monocrystalline panel of 17.89%. The temperature coefficient, a measure of the amount power output falls as temperature rises isn't particularly good at -0.39%.
Solarworld offer an excellent 25 year linear power output warranty that is amongst the best power output guarantees of the tier 1 brands on the market. Their product structural warranty at 20 years is the longest in the industry.
Their positive power tolerance is also the best in the market. What this means is that they guarantee the module will not produce less than the guaranteed power output at each stage of its life but it may produce up to 10 watts more than the rated amount.
Factors used to rate solar panel brands and how SolarWorld Solar Panels rank on each of these
We use the following factors to measure solar panels brands against each other
SolarWorld Solar Panels Warranty
SolarWorld offer a 20 year structural product warranty which is the longest of the other tier 1 manufacturers.
Their power production warranty is also quite good being a linear power production warranty rather than a step down warranty. They warrant 97% year one and an annual degradation rate of 0.5% so that they are still warranting around 92.5% output at ten years and over 82.5% at 25 years.
It is very close to the linear power output warranty offered by the better brands of solar panels such as Sunpower and LG. However, it is debatable if this makes any real difference because solar panel power output warranties require the panel has to be tested at standard test conditions if you want to claim on the power output warranty.
To do this you have to take the solar panel off your roof and take it to a test laboratory. In practice no normal consumer would be able to do this and so no normal consumer would be able to prove that a solar panel was performing at below its rated power output unless the panel was completely dead (which is very rare with a solar panel).
Efficiency of SolarWorld Solar Panels
SolarWorld Solar sits in the middle when it comes to panel efficiency. With a maximum average panel efficiency of 18.33% from its 300MS panel it sits above most of the tier 2 and tier 3 players but still below the most efficient panels from Sunpower and Pansonic.
You can read more about the efficiency of solar panels and why it is not something on which we place great weight when ranking the overall attractiveness of one solar panel over another.
Power output of SolarWorld solar panels
Solar Panels are rated at a particular wattage based on their power output at STC (standard test conditions) which involved 1000 watts of irradiation per square metre at a temperature of 25 C. (77 F).
However, real world conditions are much different to this. Generally speaking cells will operate at temperatures well above 25C and panel output will typically fall as temperature rises.
The rate at which power output falls for each 1 degree increase in temperature is called the temperature coefficient. A better panel will have a lower temperature coefficient such that although its output will still fall as temperature increases it will fall at a lower rate.
The rating system of PTC (Photovoltaics for Utility Scale Applications Test Conditions) is an attempt developed by NREL (National Renewable Energy Laboratories) to rate different panels at how much they will produce in real world temperatures.
The temperature coefficient of the SolarWorld 300 watt module is a -0.39% fall in production per 1 degree increase in temperature. The lower this number the better as this means output falls less as temperature rises. The SolarWorld coefficient is not as good as the best panels on the market that offer a temp coefficient of as little as -0.29% but it is slightly better than most of the tier 2 and 3 manufacturers and the cheapest polycrystalline panels that sit around -0.41%.
How much do SolarWorld solar panels cost?
Value or cost efficiency is a big factor because at the end of the day solar is a financial decision for most people rather than predominantly an environmental choice. In many parts of the US electricity costs are quite low and so value systems around $3 per watt fully installed are needed to give consumers the 6-10 year payback they need for solar panels to be attractive. As such we see it as a positive factor if solar panel brands have a relatively low cost of manufacture and a low selling price in the US.
The wholesale pricing of SolarWorld solar panels has become quite low in the wake of a sudden decision by the Chinese government to cut their solar feed in tariff in the middle of 2016 and the module oversupply this left SolarWorld and many other Chinese manufacturers.
This has been reflected in some excellent pricing being offered on residential SolarWorld solar systems and we have seen quite a few offers for fully installed SolarWorld solar systems as low as $2.80 per watt fully installed with a good quality SMA string inverter. Given that the 26% tax credit come off this price we are talking an excellent payback for homeowners in most parts of the country.