Solar cells are the structures which are capable of converting light energy into electricity. Over the past 20 years, the costs associated with solar cells have been steadily decreasing. It is estimated that the hard cost, which is the cost of the physical solar cell hardware, and soft costs, which include labour or costs to obtain required government permits, are about equal. Soft costs have decreased because there are more potential consumers and more installation experts for new solar cells. It has therefore become possible to manufacture solar cells in bulk and install them easily. Hard costs are less than half of what they were in the year 2000, mostly due to decreasing material costs and an increased ability of cells to capture light.
Historically, silicon has been the most popular material for solar cells. Currently, the cost of silicon-based solar cells continues to decrease, and, despite predictions to the contrary, the cost of silicon itself continues to decrease. Silicon solar cells are likely to remain popular for the next few years. Alternatives to silicon solar cells have been developed but aren’t far enough along to be commercially viable.
The Future of Solar Cells
- There are approaches to make even the current silicon technology more efficient. One method to do so is by adding an extra layer to a cell’s back to reflect unabsorbed light back through it a second time. This improves efficiency by 1-2%.
- To outpace current solar cells, a new design would need to be able to capture more light, transform light energy to electricity more efficiently, and/or be less expensive to build than current designs. One of the solutions could be to add hardware that allows the solar cells to capture more light, while not being forced to abandon the current solar cell designs.
- Another route to improving the performance of solar cells is to target their efficiency so they are better at converting energy in sunlight to electricity. Solar cells with more than one layer of light-capturing material can capture more photons than solar cells with only a single layer. Recently, lab-tested solar cells with four layers can capture 46% of the incoming light energy that hit them. These cells are still mostly too expensive and difficult to make for commercial use, but ongoing research may one day make implementing these super-efficient cells possible.
- An innovative appoach to increase efficency of solar cells is by installing electronics that let the cell track the sun as it moves through the sky during the day. If the solar cell is always pointing at the sun, it will be hit by many more photons than if it was only pointing towards the sun around midday. Currently, designing electronics that can track the position of the sun accurately and consistently for several decades at a reasonable cost is an ongoing challenge, but innovation on this front continues.
- Another alternative to improving the efficiency of solar cells is simply decreasing their cost. Even though processing silicon has become cheaper over the past few decades, it still contributes significantly to the cost of solar cell installation. By using thinner solar cells, material costs decrease. These “thin-film solar cells” use a layer of material to harvest light energy that is only 2 to 8 micrometers thick, only about 1% of what is used to make a traditional solar cell. Much like cells with multiple layers, thin-film solar cells are a bit tricky to manufacture, which limits their application, but research is ongoing. In the immediate future, silicon solar cells are likely to continue to decrease in cost and be installed in large numbers.
- The fastest improving solar technology is called perovskites – named after Count Lev Alekseevich von Perovski, a 19th Century Russian mineralogist.These have a particular crystal structure that is good for solar absorption. Thin films, around 300 nanometres (much thinner than a human hair) can be made inexpensively from solutions – allowing them to be easily applied as a coating to buildings, cars or even clothing. Perovskites also work better than silicon at lower lighting intensities, on cloudy days or for indoors.
Energy producers and consumers are more likely to adopt solar power if the energy it produces is equally or less expensive than other, often non-renewable, forms of electricity, so any improvement to current solar cell designs must bring down overall costs to become widely used.
In the immediate future, silicon solar cells are likely to continue to decrease in cost and be installed in large numbers. In Australia, these cost decreases are anticipated to increase the solar power produced by at least 700% by 2050. Meanwhile, research on alternative designs for more efficient and less expensive solar cells will continue. Years from now, we are likely to see alternatives to silicon appearing on our solar farms and rooftops, helping to provide clean and renewable sources of energy. These improvements have and will continue to be made possible by increasing bulk manufacturing of solar cells and new technologies that make the cells cheaper and more efficient.