Plug-in solar is coming – how dangerous is it and is it worth it?

The global rise in solar energy is nothing short of extraordinary. Over the past 15 years, the cost of installing a solar system has decreased by 90 percent and now represents more than 80 percent of the world’s new electricity capacity each year. So when oil and gas prices skyrocketed due to the ongoing conflict in the Middle East, solar energy was the obvious place to look for relief for many countries.

But in the UK it hasn’t just been a case of pushing for more of the same – the UK government has said it will legalize a currently illegal form of solar energy. So-called plug-in sets will be available “within months” from major shops and supermarkets.

These kits are DIY in nature, you simply bring home a few panels, place them in a sunny spot and plug them in. There are no installation costs and you can start using solar energy to power your home right away. If you move, just pack up the panels and bring them with you. Solar energy is seemingly even cheaper and available to even more people.

Many countries have already opted for plug-in solar, and there are reasons to be excited about it on a global scale, but can it really help moderate rising energy prices? how cheap is that? And is it actually safe?

Despite the rapid decline in costs, installing a traditional solar system is not cheap. For the average UK home, estimates for a A 4 kilowatt system to cover most power needs is around 7000 pounds. In the US, the average home uses about twice as much energy the cost of installing a solar system to cover it is around $20,000. These costs include expert assembly of the panels and installation of the system by a registered electrician, and making adjustments to the electricity meter so that excess energy can be sold back into the grid – reducing bills or perhaps even making a profit.

Plug-in solar is a simpler proposition. The kits are smaller than full-scale installations, so you can expect to buy an 800-watt system for around £400 and hope it covers something like 20 per cent of the average UK home’s energy needs. Installation is free as it involves nothing more than tying the panel to the balcony railing, garden fence or garage roof and plugging the cable into the socket. Once you’re plugged in, you can start using whatever power is generated.

With plug-in solar, excess energy ends up back in the grid, but you can’t make money off of it without professional installation. “Eventually, the next-door neighbor will use that energy,” he says Mark Golding at British solar panel supplier Spirit Energy.

Plug-in solar is already an established technology outside the UK. It was more than a million plug-in solar systems registered in Germany for example, since July last year. Suggestive estimates that there they have a cumulative capacity of between 1.6 and 2.4 gigawatts – enough to simultaneously boil half a million kettles.

Germany is the only country that attempts to track plug-in solar in any meaningful way, so statistics are hard to come by. But one estimate says there could be as many five million sets are in use in Europe. Plug-in solar makes up only a small fraction of the total energy mix, but for individuals, they could reduce bills and cumulatively increase the country’s ability to produce renewables.

Jan Rosenow at the University of Oxford says the spread could soar if governments press ahead with legislation to allow people to install their own panels. “Even though the individual systems are small, their cumulative impact becomes significant, both in terms of distributed generation and in terms of engaging consumers in the energy transition,” says Rosenow.

Plug-in panels are currently mostly banned in the US, but Utah became the first state to legalize them last year, and many states already similar legislation in the works. Cora Stryker at the U.S. pro-solar nonprofit Bright Saver says that outside of Utah, people have to go through the same amount of red tape to install a few solar panels at home as someone to build a 20-megawatt solar farm — a situation she says is “patently ridiculous.”

Stryker hopes plug-in solar power can ease financial woes, help slow climate change and act as the thin end of a wedge to bring the U.S. up to speed on renewable energy. “This is a watershed moment, a tipping point towards a world where the cheap costs of renewables are really passed on to consumers,” he says. Bright Saver estimates that by 2035, 24 million American homes will use solar.

How safe is it?

But despite their already widespread use, there are concerns among some experts about the safety of plug-in kits. Mark Coleshead of technical regulations at the Institution of Engineering and Technology (IET), recommends that anyone who buys a plug-in solar kit should have their home’s wiring checked for safety. And even then, the organization identified areas of concern.

One problem involves residual current devices (RCDs), safety devices found in fuse boxes that sense when current is leaking to ground — a sign of an electric shock or short circuit — and cut off power almost immediately. Most RCDs used in the UK are not suitable for current flowing in both directions and could therefore fail. In the US, the setup is different, but there are similar issues. One of the reasons Germany was able to move so quickly is that it coincidentally standardized bi-directional RCDs in the 1980s.

Another concern of the IET is what happens if there are multiple kits and there is a power failure. In theory, plug-in kits should also be switched off to prevent ‘islanding’ where one house’s power remains live. But if they’re still generating electricity, they could trick each other into thinking the grid is live and keep running. The problem then is that the current can jump the fuse box and electrocute maintenance workers in the area repairing the outage.

“That puts those people at risk,” says Coles. “It kind of goes against the ‘you just buy it and plug it in’ concept, but we’re actually concerned that there’s a public safety risk here.”

Coles agrees that plug-in solar could bring huge benefits, but wants to ensure manufacturers can demonstrate that their systems will behave safely, even in unusual scenarios.

The new scientist raised the IET’s safety concerns with the Department for Energy Security and Net Zero, and a spokesman said: “Our tests have shown that plug-in solar is safe for use on UK domestic circuits. All products will have to meet UK safety standards and we have commissioned an independent study to inform further regulations before they are sold.”

Stryker says that with the catastrophic effects of climate change and skyrocketing energy costs pushing many into fuel poverty, the greatest risk to consumers is inaction. He argues that people will adopt similar technologies regardless of whether they are officially approved and regulated, so the pragmatic approach is to help people do it as safely as possible. “Solar energy is the cheapest energy on the planet, period. It’s actually the cheapest energy that mankind has ever produced,” he says.

topics:

• solar energy/
• Renewable energy