Solar panel efficiency has become one of the main subjects discussed today when talking about solar power because in order to replace the dirty fossil fuels with clean sources of energy we need to manufacture very efficient solar cells. Let’s see Hhow efficient are solar panels.
Solar Panel Efficiency – Definition
Solar panel efficiency represents the amount of sunlight (under the form of energy) that is converted into electricity by a solar panel.
The efficiency of each solar panel or solar module is directly related to the efficiency of the solar cells contained by the panel and is represented in percentages.
VDS Solar Systems is providing solar solutions to lower your electricity bills and avoid the frequent power disruption in Kerala.
To determine the efficiency of a solar panel, all modules are tested using the Standard Test Conditions (STC), which means a temperature of 25°C and an irradiance of 1,000 W/m2.
The standard conditions are trying to replicate the conditions obtained in a sunny day with the incident light hitting a sun-facing 37°-tilted surface.
If the solar efficiency is measured at 18% in these conditions, a solar panel with the surface of 1 m2 will generate 180 Watts.
Before reaching the market, all solar panels are tested under extreme weather conditions such as strong wind, hail, snow, ice, exposure to chemicals, UV degradation, humidity, insulation resistance and thermal cycling.
Wind
A strong wind can damage the solar panels pretty much, so all solar panel manufacturers will conduct extensive wind tunnel testing to avoid any potential damage.
Hail
The hail test consists of shooting artificial hail from a pneumatic hail cannon in the direction of the panels at a speed of 20 to 30 m/s, and the solar modules need to remain intact.
Snow
Snow is the main enemy of the solar panels because even a thin layer of snow that covers the panel will stop the panel from producing electricity.
This is the reason why snow must be removed from the panels right away to avoid losing energy.
Removing the snow is very important because besides reducing the efficiency of the panel, a wet snow being very heavy can damage the panel.
Solar cells need to be coated with silicon in order to prevent the creation of the ice on their surface.
Even a small piece of ice that forms on a solar cell can seriously reduce the efficiency of the solar module.
Chemical Residues
If chemical residues will land on a solar panel, its efficiency will be slightly reduced, so we have to clean the panels or we can wait for the rain to do the job.
UV radiation
The structure of the solar cell can be delaminated due to the action of the UV radiation of the Sun.
Another consequence of the UV radiation is the fading of the solar cells that could occur over time.
Damp Heat Testing
To test the durability of the solar panels in highly humid conditions, a damp heat testing will be carried out.
This test is very important to check if the solar panels can resist over time in very humid conditions because humidity is a great enemy of the panels producing corrosion and connection issues, which always leads to the decrease of the panel efficiency.
Insulation resistance
Insulation resistance of the solar panel needs to be tested to see if the panel has current leakages on its sides.
A solar module manufactured using quality materials will always be properly insulated and will keep its integrity a long period of time.
Every type of PV (photovoltaic) solar panel will love the light, but not the heat because a heated solar panel will produce less electricity (decreased efficiency).
It is important to know if the solar panel tested can work well in the conditions given by a hot day during the summer when the outside temperature could create problems for the solar panel by affecting the solar cells, the interconnections, the solder bonds and connections of the module.
Thermal cycling
A solar panel with good thermal cycling needs to work the same during the winter and also during the summer despite the very hot or cold outside temperatures.
Testing the solar panels in extreme conditions is important because this way the low quality solar modules will be prevented from reaching the market.
All solar panels that are sold on the market need to provide a long term warranty and also an efficiency, which will slightly decrease only after a very long period of use.
How Efficient Are Solar Panels Today?
There are three main types of solar modules available on the market today, and the efficiency of these solar panels represents a different value for each.
1. Monocrystalline Solar Panels
This type of solar modules consists of solar cells that are made from a single high purity silicon ingot, which means that these solar cells will provide a high efficiency of the panel.
The monocrystalline solar modules available on the market today have a top efficiency around 22%, and their price is pretty high (at least $1 per Watt).
This Monocrystalline Solar Panel generates 280 Watts and 24 Volts.
Monocrystalline solar panels come with a 25-year power output warranty.
2. Polycrystalline Solar Panels
The solar cells used by these panels are cheaper because they are manufactured using melted silicon that is poured into a shape that is then cut into wafers.
The polycrystalline solar modules are slightly cheaper than the monocrystalline solar modules because the waste resulted in the manufacturing process of the polycrystalline solar cells is very small compared to the amount of waste resulted while manufacturing monocrystalline solar cells.
The efficiency provided by a polycrystalline solar panel is around 17%, which means that we need to buy more panels (than in the case of a monocrystalline solar PV system) to obtain the same output (the surface covered by the poly solar modules will be also higher).
This Polycrystalline Black Solar Panel has an output of 270 Watts and has about the same size as a mono solar panel.
Polycrystalline solar panels also come with a 25-year power output warranty.
3. Thin Film Solar Panels
There are several types of thin-film (flexible) solar panels after the materials and substances used to manufacture this type of solar cells.
- Thin-film solar modules using amorphous silicon (a-Si);
- Thin-film solar panels that use Cadmium Telluride (CdTe) solar cells;
- Thin-film solar modules using Copper Iridium Gallium Selenide (CIG, CIGS) solar cells;
- Thin-film solar panels using organic photovoltaic (OPV, DSC, DYSC) solar cells.
These flexible solar panels are more affordable than the PV solar modules (around 25% cheaper), but they provide an efficiency of about 12%.
Due to the fact that they are less efficient, they require about 50% more space for a given project size.
This Flexible Solar Panel generates 136 Watts and 24 Volts and works well in all light conditions, including partial shade or in a cloudy day.
The lifespan of the thin-film solar modules is slightly shorter, around 20 years.
What You Need to Know Before Choosing a Solar Panel System for your Home?
When choosing a solar panel system for your home, you don’t need to know the technical specs about this technology or about the electric current because the company that will install and maintain your solar PV system can answer to all your questions.
However, before contacting any solar company, you first need to know that the solar panels available on the market today are manufactured in different countries of the planet.
China and India are driving down the prices of solar today by producing solar panels and solar components at lower prices.
Choose a solar PV system that can cover your energy demand
However, you are the last person that will decide what solar power system is suited for your home.
After deciding the size of the system check your rooftop to see if it is suited for solar.
You need to have a rooftop facing south if you live in the Northern Hemisphere, and a rooftop facing north if you live in the Southern Hemisphere.
If your rooftop is not suited for solar, you can install the solar power system in the yard (if you have space).
Check your electricity bill to see the monthly consumption (mine is 1 MW during the summer, and 2 MW during the winter because I use AC units with inverter for heating).
If you know your average consumption of energy you can choose a solar power system that can lower your energy bill (if you have a tight budget, a 4 KW system will generate on average about 20 KW of clean electricity per day and about 600 KW per month, so it has the capacity to lower your energy bill).
However, if you want to have zero energy bills you need a solar power system that can cover all your monthly energy consumption (or at least during the summer months).
When choosing your solar power system, also check for the proper solar modules (in terms of aesthetics and style) because you don’t want a solar PV system that doesn’t look good on your rooftop.
Conclusion
The technology used today to harness the clean power provided by the Sun has a top efficiency of around 22%, which means that 78% of the sunlight is lost in the process.
Many teams of scientists are working today to develop a different technology that can provide a higher efficiency because if we want to replace the fossil fuels with renewable energy sources such as solar, wind, hydro, geothermal, biomass, tidal, nuclear fusion, etc. we need to increase the output per square meter of solar.
