Solar panel efficiency can be defined as a measure of the electricity produced in watts based on the amount of solar energy absorbed by solar cells. Today, there are thousands of solar panels available in the market and this presents a challenge to many solar buyers when they want to select the best solar panels that are suitable for them based on solar panel cost and design aspects of the solar PV project.
Solar panel efficiencies can range from as low as 10% to as high as over 20%. Cheaper thin-film solar panels can have efficiencies of below 10% while most Monocrystalline/polycrystalline panels will have a solar panel efficiency ranging between 13 to 15%. Premium solar panels from very well-known and established solar panel manufacturers such as SunPower, Panasonic, SolarWorld, Solaria, etc will have solar panel efficiencies ranging between 20% to 24%.
Solar panel efficiency and space requirements:
Since solar panel efficiency is a measure of the electrical output of specific solar panels versus solar irradiation hitting or being absorbed by the solar cells; the amount of space to install your solar panels is affected by the level of efficiency of the solar panels. Generally, the higher the efficiency, the less space is required to install the solar panels and vice-versa.
This means that you require less surface area for high-efficiency solar panels to produce the same amount of power as compared to low-efficiency solar panels. For example, a typical 20% efficient solar panel would convert 20% of the solar energy landing on its surface into electricity. On the other hand, a 15% efficient solar panel would convert 15% of the solar energy landing on its surface into electricity. This implies that for a 300 watts rated solar panel for example, with different efficiencies, you will need more 15% efficiency solar panels compared to 20% efficient solar panels because you need more surface area to produce the same amount of power as captured in the formula:
Efficiency % = Electricity produced (in watts) divided by Solar Energy Absorbed
Types of solar panels and their efficiencies
Many thin-film solar panels have lower efficiencies and hence are widely used in commercial projects since they require a big surface area, are cost-effective and are not bulky in nature. Thin-film solar panels are made with lower efficiency products such as amorphous silicon; cadmium telluride etc and cheaper versions have efficiencies of less than 10%. However, today with the advancement of solar PV technology, high-efficiency thin-film solar panels (about 20%) are available but are costly because higher efficiencies require technologies that are harder to produce at scale and at an affordable cost.
A high number of monocrystalline/polycrystalline solar panels have high solar efficiencies compared to thin-film because they are made of high-efficiency materials (e.g. silicon). Solar panel efficiencies of these types of solar panels can range between13% to 24% and efficiencies continue to improve because of research and development (R&D) efforts in this space.
So, should you only consider solar panel efficiency when selecting your best solar panels?
It is very easy to get confused about which solar panels are the best for you, but that depends on factors such as affordability and availability of space that we try to capture here.
- Affordability: Solar panels with higher efficiencies are in many cases from premium solar companies which means they are made by some of the best solar panel manufacturers in the world that employ innovation and have invested a lot of capital in producing very high quality (premium) solar panels. Such solar panels are definitely recommended to enhance system reliability and durability due to the manufacturing engineering that is employed in producing such solar panels. However, if for affordability reasons, you are unable to get premium panels; there are economy & standard solar panels whose solar efficiency might not cater to all the system reliability issues. For example, you might not get product warranties that are equal to the lifespan of your solar panels. Also, this might affect the bankability of your project if you are looking for a loan to develop your project thus calling for high-interest rates. Many premium solar panel manufacturers are listed on a stock exchange and have a strong balance sheet and this enhances the bankability. However, depending on your budget there will always be a trade-off for using economy, standard or premium solar panels.
- Availability of space: If you have a good amount of space, using lower efficiency solar panels will be ideal because that means you will reduce the overall cost of going solar and vice-versa. However, if reducing your carbon footprint is one of the reasons for installing solar panels, then perhaps this will not be ideal because lower efficiencies call for the installation of many solar panels compared with when installing high efficient solar panels. Monocrystalline/polycrystalline PV technologies are good for places limited in space especially in the residential sector while thin-film solar technologies are good for applications where space may not be a limiting factor to going solar.
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