By: Urslah Ngala, Technical Sales Assistant, Creative Innovations Ltd

The ongoing energy transition to renewable energy has seen increasing traction for solar energy. More people are moving away from the increasing electricity bills towards solarization. This has resulted in an increased demand for products in relation to solar-powered systems.
Solar panel modules are responsible for effectively converting sunlight into solar electricity and they are the most vital components of a solar-powered system. However, the market is flooded with counterfeits and it’s seemingly futile to tell the difference especially if you don’t have background knowledge in the field. So, how then do we decide on the most vital component of a solar-powered system, high-quality solar panels vis-à-vis counterfeits?

Here are a few things to consider as you purchase your solar panels:

1. The Solar Panels Power Ratings

The power rating represents the solar power output under ideal conditions, Standard Test Conditions (STC). Upon installation, the solar panel outputs may not be exactly as represented in the power rating. This is because the ideal conditions aren’t the same as real-time conditions.
The higher the solar power rating the higher the potential expected power output. The power rating may be discerned from the solar panels’ nameplate. A nameplate is often a manufacturer sticker located at the back of the panel. It is the official power production rating of the solar panel.

2. The Solar Power Tolerance
Power tolerance is a measure of how much electrical power a solar panel can produce above or below its rated capacity at any time. Power tolerance is a measure of the actual range a module can deviate from its specified STC max power.
For example, a power tolerance of -5%/+5% on a 100-watt (W) panel would mean the solar panel could produce 95 W to 105 W under real-world conditions.

OR

If a 220W panel has a Power Tolerance of -10% / +10%, the panel could have an actual Max Power of anywhere between 198 and 242W.

A 0% negative power tolerance means that the panel should always produce power equal to or greater than its rated power, this is not possible because the STC are not the same as real-time world conditions

3. The Efficiency of a Solar Panel
The efficiency of photovoltaic solar panels is related to the quality of their photovoltaic (PV) cells. The conversion efficiency of a PV cell is the percentage of solar energy shining on a solar panel that is converted into usable electricity. The more efficient a solar panel, the more energy output per light hitting the cell. This will, in turn, take up less surface area to meet your energy requirements.
However, there are other factors that influence efficiency. For instance, solar panel design affects efficiency mainly by the way the cells are laid out and configured along the panel. Orientation of the solar panels – called solar panel angle or tilt – is important to obtain the full advantages of the sun’s radiation.
The efficiency of a solar panel is going to represent how effectively solar panels can convert solar radiation into solar electricity. The solar panels with the highest efficiency of a solar panel that is commercially available today have an efficiency of a solar panel rating of 23%.

4. The Solar Panels Temperature Coefficient
Don’t get me wrong, as much as solar panels are made for the sun, however, they are sensitive to temperatures. Solar panels are manufactured under Standard Test Conditions (STC). Temperatures above the optimum levels (STC temperature of 250C) decrease the solar power output capacity, while temperatures below the optimum level increase the voltage of solar cells. This introduces an important aspect, the Temperature Coefficient.

The temperature coefficient tells us the rate at which solar panels maximize power output and the rate at which efficiency rises or drops with a rise or drop in the optimum temperature
Most solar panels have a temperature coefficient of around -0.3% / °C to -0.5% / °C. For example, a solar panel with a temperature coefficient of -0.37% / °C, means that for every 1 °C above 25°C, the solar panel decreases efficiency by 0.37%. So, if your panels are at 35°C (95°F) and have an overall efficiency of 17%, then their true efficiency at that temperature will be closer to 16.4%

5. International standards of solar panels
Just like products are subjected under the Bureau of Standards to ensure the quality of the product, so are panels. The International Organization for Standardization (ISO) is the body responsible for the quality assurance standards of solar panels. In the manufacturing industry, the compliance standard is known as the ISO 9000 series. Solar panel manufacturers can be certified ISO 9000-compliant to indicate that they meet the quality standards. Nonetheless, the lack of ISO certification isn’t necessarily an indicator of a menial product but buying from a certified manufacturer is an indicator of quality.

In conclusion, in the spirit of “buyer beware”, the above are key considerations when purchasing and installing solar panels that enable great returns and benefits of solar energy.

About author

Urslah Ngala is Technical Sales Assistant at Creative Innovations Ltd, Nairobi, Kenya. She holds a Bachelor of Science in Renewable Energy and Technology from the Multimedia University of Kenya. She is a renewable energy enthusiast. She is a systematic professional and pragmatic with technical knowledge of current trends in renewable energy, climate change and sustainable development. She is championing renewable energy’s efficiency in day-to-day activities, the 4th Industrial Revolution (4IR) and climate change. Her goal and passion are for clean and affordable energy for all.