Ecotricity explains Bifacial Solar Panels
As Britain’s greenest energy company, our sun parks generate electricity from the ultimate free power source – the sun. Whatever the weather, solar energy is generated when photons from the sun create a flow of electricity in the solar panel, which is why you’ll sometimes see them referred to as photovoltaic panels.
The technology used in solar power has come on in leaps and bounds in recent years. One particularly exciting development is bifacial solar panels – we’ll soon be using this technology in our hybrid energy parks.
But what is a bifacial solar panel and why is it better than the ones we’re all familiar with? To find out more about this latest generation of solar panels, who better to ask than Ecotricity’s Head of Generation, Steve Ellis…
Steve, what exactly is a bifacial solar panel?
“Most people know what a solar panel looks like. It either sits flat on a surface (like a roof) or up on frames in a sun park in order to face the face the sun more directly, and generates electricity from sunlight hitting the side that’s facing upwards.
The new bifacial panels in our sun parks don’t have a frame covering the back. Instead, they have a second side that’s able to generate electricity, this time from the reflected light that comes from underneath the panel rather than direct from the sun.”
“On the same area, a sun park will generate around 7 to 10% more electricity with bifacial panels. That’s a significant increase for a very small extra cost in the manufacturing of the panels themselves.
The exact amount of extra energy generated depends on the ground beneath the solar panels. More sunlight reflects off lighter ground – just think of how bright the glare is off snow on a sunny day. Here in Britain, we keep the grass short in our sun parks in order to get the maximum possible amount of reflected light.”
How much energy do today’s solar panels generate?
“Talking about a typical solar panel – or sunmill as we like to call them! – around 10 years ago we were looking at solar panels that might have generated about 280 watts per panel. Early next year, there’s a 500 watt panel coming on the market – it’s the same size but generates almost twice as much electricity!”
How long do solar panels last?
“Improvements in the amount of energy we can get out of them will certainly continue for the next few years. Module efficiency will continue to improve due to the application of new technologies. Lab scale experiments are hitting 30% to 40% efficiency, currently we are at about 20% efficient.
The structure of the solar panel – how it’s put together – makes a difference. Essentially, there are 2 types of polycrystalline – blue tint in colour, slightly cheaper as they tend to be less efficient, and monocrystalline – black colour and a bit more expensive due to improved efficiency.
As for their actual useful life, that’s a good question. When our planning permissions are given, we build sun parks to last for 25 years – but there's evidence to show that solar panels will generate clean electricity for much longer as long as the panels are looked after.”
Do bifacial solar panels cost more?
“There are additional costs for the panels and for installation (as the frame needs to be a little sturdier because it can’t have a back to it) but these are marginal, the amount of energy generated from the extra side balances the extra minimal costs.”
How long does it take solar panels to pay for themselves?
“The amount of time it takes to get back the energy used in manufacturing and installing our sun parks is around two years. After that, for the next 20 years, or even 40 years if the predictions hold true, sun parks will just keep producing clean energy – and of course there’s no more carbon being produced apart from the very small amount involved in maintenance.”
Can you use bifacial panels on a roof?
“One thing that’s important about bifacial panels is that the higher up in the air they are, the better, because you get more light underneath them. In a sun park, we’d sit them about four metres up which gives them lots of space underneath while still making maintenance not too much of a problem.
In a domestic setting, you don’t need planning permission for single face panels because they sit flat but with bifacials you’d need to have them about 4 metres above your roof!”
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