Ultra-high efficiency arrays being developed for the residential PV market

Innovation and mind-spinning technological invention have often acted as the foundation blocks for the solar industry, and Swiss startup Insolight is continuing that trend with the idea to bring space-age cells to the mainstream market. This high-end solar technology, which has efficiency levels above 40%, is currently way too expensive to compete with the PV modules that are on the market, so Insolight has come up with some ingenious solutions to make it cost-effective and hopefully to start installing it on residential roofs.

The key to the cost reduction is to concentrate the sun’s rays onto small areas of the high-efficiency cells, so you only have a small area of PV cell. To do this, Insolight has developed plastic lens, which can be layered on top of the solar cell, and which focus light from a larger area onto it. To do this the modules were also required to track the sun to concentrate the light.

Insolight is happy to admit that it did not come up with the idea of concentrating sunlight onto ultra-high efficiency cells, as it has been done before, but these initial forays into the field required dual axis tracking equipment to track the sun. The difference with Insolight is that all of the tracking has been integrated into their flat panels, meaning that they can be installed on rooftops, and not just for utility-scale arrays. Insolight has labelled this technology: optical micro-tracking.

“We analyzed why this method of concentrating PV had been unsuccessful, and we saw that they reached good efficiency levels, but they used dual axis trackers,” Insolight Co-Founder and CEO Laurent Coulot explained to pv magazine. “This means it is only for utility-scale, as you can’t put these on your roof. This is challenging, as you need to align it with large structures, which creates maintenance issues, and various other issues.

“These type of modules need to track the sun, because in optics in order to concentrate the light, you need to have the optics more aligned with the sun rays coming in,” Coulot continued. “Our idea was to concentrate the sunlight, but we want to do it in a flat panel assembly. So we have an optical system that allows you to redirect the sunlight without tilt, and this tracking system can move laterally by small strokes instead of rotating, so that you can insert it in the panel.”

Raising the efficiency

Using this unique method, Insolight was able to generate an incredible efficiency of 36.4% on a small-scale prototype of their module. Although this was just a prototype, Coulot was confident that the company will be able to scale this up to reach the same level of efficiency, but he admits that a lot of work is going into the scaling up process.

In terms of costs, the company is predicting that the panels will be significantly more expensive that standard PV modules on the market right now, but with installation costs included, it won’t significantly raise the cost of having one of its systems installed on a residential roof.

“We are targeting 2 to 3 times more expensive for the panels alone,” Coulot explained. “But the panel costs are only around 20% of an installation. When you take into account all of the costs involved in getting your panel installed on your roof and to the grid, we predict that it will only rise from $650 per m2 to $850 per m2, in the U.S. for instance. This is only a 30% rise in installation cost.”

Although the system may cost 30% more in total, what the customer would get back in terms of efficiency, which would translate into lower electricity costs, would outweigh this increase. Insolight is hoping that with its systems it will be able to bring electricity costs down to below 10 cents per kWh in the U.S. market, for example.

But when might we see these commercial products on the market.

“Now the goal is to go to increasing the capital and going to the next step which is developing the product,” said Coulot. “The target is to have the first pilot size array running for September 2017. Then the next goal is to go to production, eventually heading to mass production.”