Most of the solar panels you see are mono-facial solar panels. Sunlight hits the top face of the solar panel, and it generates electricity. But those aren’t the only kind of solar panel that is out there. There’s another type – bifacial solar panels. With bifacial panels, an extra part of the solar panel produces electricity – the back face.
Bifacial solar panels are solar panels that can capture sunlight on both their front and back sides and are an interesting new solar solution for certain solar installations. Bifacial solar panels utilize technology across modern solar modules and cell development advancements, such as high watt modules, higher efficiency modules, half-cut cell designs, and more. Coulee has developed its bifacial solar panel in the race to develop the most efficient type of solar energy product.
The higher efficiency rating of bifacial solar panels not only increases your overall energy output but the output of your solar energy system under less than ideal sun conditions. At the same time, half-cut cell technology reduces the risk of “hot spots” developing on your solar modules, extending the lifetime of the PV modules and increasing the output of your solar array.
Bifacial solar panel technology takes advantage of all three of these technologies and combines them into a singular PV module, capable of producing up to 30% more energy output.
Why Bifacial Solar Panels?
When sunlight hits the face of the panel, not all of it is absorbed on the first pass. Even the most efficient solar panels only have an efficiency rating of 20-24%, which means around 80% of the potential energy is “lost” as it passes through the PV cells.
By installing the bifacial solar panels over a reflective surface, the light can bounce back through the panel a second time, giving the cells on the backside of the panel a second chance to capture and convert energy.
Since the solar panel has a second opportunity to re-absorb sunlight, bifacial solar panels enjoy increased efficiency over their traditional counterparts. Given that bifacial solar panels provide higher output from the same form factor, it’s easy to see why the solar industry is excited about them.
Optimize Your Bifacial Installation
Bifacial solar panels can be a great way to pack a big punch with less room. If you’re limited on space, opting for bifacial panels can help your system produce more electricity with fewer panels. However, bifacial panels aren’t for everyone.
Some of the best practice recommendations to optimize your bifacial installation and achieve increased ROI and lower LCOE are as follows:
- Site selection: The cost of land affects how bifacial can be optimized. For places where land is scarce and expensive, panels should be laid flat on the ground to ensure maximum energy collection over a given land area. However, where land is cheap, bifacial panels can have optimal spacing and higher yields. Also, bifacial yields are greater where the diffuse light energy is greater, which means at higher latitudes, the bifacial yield will be greater than at lower latitudes.
- High albedo: The environment selected should have a high albedo. Desert sand is a good option. The best option is white concrete or highly reflective roof foil. Snow and ice also have a very high albedo.
- Panel height: This will vary from site to site, but 1 meter has provided benefit to cost ratios. Increasing panel height requires other variables to be measured, such as wind speed and lift from the tilt, and therefore requires stronger ground mounts.
- Tilt: This will vary from site to site, but generally, 2~15 degrees more than the mono facial tilt has been shown to be effective.
- Row distance: This will vary from site to site, but 6 to 8 meters row distance has been shown to produce good results. Of course, the cost of land or the available space must be considered, and if the cost of land is too great, then a greater row distance will increase your LCOE. Ideally, somewhere that land is very cheap can be used to increase row distance cost-effectively.
- Greater MPPT density: Using string inverters with more MPPTs (maximum power point tracking) is an effective way to reduce string mismatch and ensure efficient performance. The more MPPTs per watt, the better.
- Single-axis tracker: Researchers from the Solar Energy Research Institute of Singapore have concluded that bifacial installations with single-axis tracking can increase energy yield by 35% and reach the lowest LCOE for most of the land area on the planet. Although dual-axis trackers achieve the highest energy generation, their costs are still too high and are not cost-effective. The researchers wrote: “In general, with the same mounting structure, bifacial configuration outperforms mono facial configuration. Tracker configurations outperform fixed-tilt configurations significantly, with dual-axis tracker installations having a marginally higher yield than one axis.”
Bifacial solar panels offer many advantages over traditional solar modules. Power can be produced from both sides of bifacial solar panels, increasing total energy generation. They’re often more durable because both sides are UV resistant, and potential-induced degradation (PID) concerns are reduced when the bifacial module is frameless. Balance of system (BOS) costs are also reduced when more power is generated from bifacial solar panels in a smaller array footprint.