With hundreds of different solar panels on the market, identifying which panels to use can be tricky.
Using the latest solar cell innovations to develop the most efficient and reliable panels with the longest life and highest performance – the solar industry has produced both Bifacial and Half-Cell module technologies. Arguably not the newest of technologies but with ongoing development, the affordability of the two different types of panels make them more accessible in the ever-crowded market.
What is Bifacial?
The short explanation is that the bifacial cell within a solar panel not only generates electricity from the front but also the back.
Bifacial solar technology has been available for several years but is becoming more popular as the cost to manufacture the high-quality monocrystalline cells required continues to decrease. Bifacial cells in the right location and conditions can produce up to 30% more energy than traditional mono facial panels. Bifacial solar panels typically use a glass front and clear rear polymer backsheet to contain the cells which allow reflected light to enter from the rear side of the panel. Bifacial modules can also use a glass rear side which lasts longer and can significantly reduce the risk of failure.
The 2020 International Technology Roadmap for Photovoltaics (ITRPV) predicts that the market share for bifacial modules will increase from 10% in 2020 to at least 35% in 2030.
What is Half-cell?
Quite simply, half-cell modules have solar cells that are cut in half, which improves the module’s performance and durability. Traditional 60- and 72-cell panels will have 120 and 144 half-cut cells, respectively.
Half-cells were introduced in order to reduce interconnection losses. There is an extra stage in the manufacturing process for cutting the cells but the benefit to module power is evident in the graph below.
When solar cells are halved, their current is also halved, so there are less resistive losses through the bus bars thus the cells can produce more power. This also means the bus bars width can be reduced by half which means a reduction in the effects of cell shading and increased efficiency. Smaller cells experience reduced mechanical stresses, so there is a decreased opportunity for cracking. Half-cell modules have higher output ratings and are more reliable than traditional panels.
The lower current also translates to lower cell temperatures which in turn reduces the potential formation and severity of hot spots due to localised shading, dirt or cell damage. Also, the shorter wire distance to the centre of the panel from the top and bottom further boosts efficiency and can increase the power output of a similar-sized panel by up to 20W.
Module manufacturers are so impressed with half-cell technology that they are making all of their future module models half-cell, such as; TrinaSolar, Longi and Jinko among others.
The picture above shows the expected market share for modules with full, half and quarter cells. Other includes 1/3, 1/5, 1/6 for 210 x 210mm² .
Commercial Applications
Large solar PV systems with bifacial modules are still quite new to the market, many questions that were asked during the launch phase can now be answered with some certainty thanks to the availability of data. Bifacial modules have been tipped for large-scale power plant installations i.e. utility-scale sized projects. More power can be produced for 30% less module area covered essentially.
Half-cell technology can also suit commercial applications. We can also predict that the performance in the long run is similar to standard modules or even slightly better.
Low photovoltaic module costs imply that increasing the energy yield per module area is now a priority. The ability to harvest sunlight from both sides of a cell will strongly penetrate the market but that more field data, better simulation tools and international measurement standards are needed to overcome perceived investment risks. What can be confirmed from the data that we already have is that overall component costs of solar systems is falling. Battery storage being included in solar systems is increasing and bifacial and half-cell technologies are taking a larger share of the module market.
Reference: https://bit.ly/itrpv-documents