Solar Panel Bandgap

Solar panels produce electricity when sunlight hits their surface and they produce the most energy when that sunlight is exactly perpendicular to the panel face.

Solar panel bandgap.

For solar cells made from silicon to provide pv electricity the photons which hit a solar cell must have energy greater than 1 11 ev. Only photons with at least the band gap energy will be able to free electrons to create a current. To knock an electron of a silicon atom at room temperature we must provide a packet of energy greater than 1 11 ev. Solar panels on a shallow roof capture more sunlight during the summer season whereas solar panels on a steep roof will produce more power during the winter.

A simple heterojunction design evolved in which p type cdte was matched with n type cadmium sulfide cds. Solar cells made from cadmium telluride cdte the bandgap energy is 1 44 ev. Traditional single junction cells with an optimal band gap for the solar spectrum have a maximum theoretical efficiency of 33 16 the shockley queisser limit. While you can use solar panel trackers to keep them at the optimum angle at all times the costs and complications involved aren t worth it in most cases.

Therefore the best angle for your solar panels is the one that allows the panels to get the most direct perpendicular light. Solar cells with multiple band gap absorber materials improve efficiency by dividing the solar spectrum into smaller bins where the thermodynamic efficiency limit is higher for each bin. This first calculation used the 6000k black body spectrum as an approximation to the solar spectrum. The most efficient bandgap is found to be at 1 34 ev with a maximum power conversion efficiency pce of 33 7.

Put in terms of radiation all the photons in the visible spectrum are strong enough to causeelectrons to jump the band gap. Solar energy materials solar cells 91 2007 1599 1610 improving solar cell efficiency using photonic band gap materials marian florescua b hwang leea irina puscasuc martin prallec lucia florescua b david z. Subsequent calculations have used measured global solar spectra am1 5g and included a back surface mirror which increases the maximum efficiency to 33 7 for a solar cell with a bandgap of 1 34 ev. The semiconductor chosen for a solar cell has to absorb as much of the solar spectrum as possible therefore a low band gap is desireable.

Reaching this ideal bandgap energy can be difficult but utilizing tunable perovskite solar cells allows for the flexibility to match this value. Research in cdte dates back to the 1950s because its band gap 1 5 ev is almost a perfect match to the distribution of photons in the solar spectrum in terms of conversion to electricity.