Increase yield PV modulesilumen
PID box undoes daytime damage to solar panels at night.
You might not think when you see them gleaming on the roofs of Flemish homes, but most solar panels suffer from significant degradation, with electricity yields decreasing in just the first few years after installation.
But one Flemish engineering company is conquering the world of solar electricity systems, or photovoltaics (PV), with a clever invention – a rejuvenating device for solar panels.
Potential Induced Degradation (PID) is well-known and feared by solar panel manufacturers the world over. Because of poor grounding, high voltages and inadequate shielding between individual solar cells, leakage occurs, which dramatically reduces the electricity yield of solar panels. In some cases, the loss can be as high as 80% and can already occur in the first two years after roof installation. PID also increases the fire hazard of PV systems.
The reduced electricity yields mean that the payback period of the costly installations is prolonged by many years – a development that has been disillusioning solar panel owners and has been giving solar energy a bad rep.
With its “PID box”, the Limburg-based engineering company Ilumen has devised a solution to the problem. The box automatically regenerates the solar cells by reversing the degradation process. The result? Not a single rooftop panel needs to be replaced because of PID problems.
So how does it work, this PID box? The device – which looks like a plastic box – is connected to the PV system’s power outlet, right between the panels and the inverter (a device that converts the generated direct current to alternating current and then delivers it to the electricity net). At night, when the solar cells are inactive, the PID box reverses the direction of the current and rejuvenates the degenerated cells.
“We just reverse the degradation process,” says Ismaël Ben-Al-Lal, manager at Ilumen. “And the regeneration process happens much faster.”
But knowing that it “reverses the degeneration process” doesn’t make the device look less like a plain, metal box. What does the PID box do exactly, on the physical level of the individual solar cells? Ben-Al-Lal (pictured, left) says that it reinforces the PN junction, or the core of the semiconductor technology in every solar cell, by driving a high electrical current through the cells. Because this involves high voltage, the panels are temporarily disconnected from the inverter. According to the company, the PID box is the missing link in every existing PV system.
A gun and a toothpick
The biggest challenge for the Ilumen engineers was ensuring that the regeneration process could be implemented for existing installations. According to Ben-Al-Lal, few users like to take down their solar panels to have them rejuvenated somewhere elsewhere – and repeat the process every two years at that.
“That’s why we equipped our PID box with an algorithm that detects the susceptibility to PID for every individual cell,” he explains. “Based on that information, an optimal current is sent during the regeneration process.”
The PID box might rejuvenate solar panels, but it cannot ultimately prevent the deterioration process. According to Ben-Al-Lal, this wouldn’t be technically feasible because it would require fundamental technical adjustments at the cell level. “Actually, we are competing with a gun against a person with a toothpick,” the Ilumen manager says, explaining that PID still occurs during the day, but that it doesn’t begin to compare with the night-time regeneration process. “Because PID has a certain inertia, it won’t get the chance to reduce the overall yield of solar power.”
Ilumen is currently conquering the entire PV market with its PID box and other related technology. The company is also involved in several large-scale projects around the world. Ilumen technology was, for instance, used in a PV installation in Asia with a capacity of no less than 40 megawatt. “These are projects backed by big investors who do a really short follow-up,” Ben-Al-Lal explains. “What they want – before anything else – is a high yield.”
For small customers – think Flemish households with rooftop solar panels – Ilumen has developed a miniature version of the PID box. And just six months after the launch, customer demand for the product has gone through the roof.
“Currently, we are running seven weeks behind our production schedule because we can’t keep up with the orders,” Ben-Al-Lal says. The majority of the buyers are solar panel manufacturers, he says, because they like to present the PID box solution to their customers.
But the guarantee policies that tie manufacturers, installers and end consumers are causing some makers not to embrace the device. Ben-Al-Lal explains that some large installers of PV systems that have filed claims with manufacturers don’t want to hear about the Ilumen box.
“They just demand new solar panels,” he says, because, after one more year, it is no longer the installers’ problem; they’re only tied to a two-year customer guarantee. “When they have installed the new panels, the problem for them is resolved,” the Ilumen engineer explains. “Of course, that is not a sustainable or cheap solution.”
Bron : Flanders Today
Improve the performance of your PV installation with the PID box. More Info: What is PID