Solar farm powering over 10,000 homes

We're starting our search for solar energy here in Cambridgeshire, home to one of the largest solar parks in the country, Vine Farm. James Tytko paid a visit to the site and was joined by two employees from BayWa, the German company which built and now maintains the park. He wanted to see the farm action and learn how photovoltaic, or PV, solar panels actually work…

Nicola - It's amazing how big this place is!

James - Yes, I know!

Nicola - Can I just ask you to put that on?

James - High-Vis.

Dan - I'm Dan Bishop, I'm an area manager covering the Midlands area for BayWa.

Nicola - I'm Nicola Crosby. I'm the solar operation and maintenance coordinator for the BayWa operation services team.

James - So the sheep - they're just allowed to graze in and around the solar panels?

Dan - Absolutely. The site's been built with grazing in mind. There's sheep protection built around to stop them damaging any of the infrastructure. And having the sheep on site obviously helps maintain the ground conditions. It stops the grass growing too long - that can shade the modules, which can affect production. If the grass grows too long and dries out in the summer, that can be a fire risk. So having the sheep on site for us is fantastic. The site itself is spread over roughly 200 acres. There are just shy of 150,000 solar modules. What you can see here is a very small percentage of the actual site. It goes way in the distance over there, spread over four fields.

James - And I've read online that this is either one of the biggest solar farms in the country or the biggest solar farm in the country?

Dan - I believe at the time of building in 2015, it was the biggest. But BayWa are building solar farms this year, and I believe we've got one in the pipeline that is going to quite dramatically bigger.

James - How exactly do these sheets of Silicon that we can see as far as the ICS turn sunlight into electricity, which powers our homes?

Dan - These modules they take in solar irradiation from the sun, which is exactly the same thing that gives you a tan effectively. The solar radiation then excites electrons inside of those cells, which generates a DC voltage

James - Direct current?

Dan - Direct current, exactly. The solar modules are then daisy-chained together effectively, in what we call series, which increases the voltage and makes it easier and more efficient for the inverters to convert into AC, which is alternating current. It makes sure that the frequency and the voltage that it's putting out matches the grid, hence it's called a grid-tied solar inverter. And then from there, it converts it to the grid voltage grid frequency, and feeds it back to our private substation, which then feeds it back to the DNO substation, which is district network operator. Each module putting out roughly 350 Watts at peak and in total, that'll give us just shy of 46 megawatts of power. 46 megawatts roughly, give or take, will power on average 11 and a half thousand homes.

James - What goes into maintaining a site like this? What other sort of technology or innovation are you using to keep something like this up and running? I mean, it's so massive as we've described.

Dan - On a site like this, obviously due to the sheer scale of it, things do go wrong. It's inevitable. So the solar inverters, like any other piece of electrical equipment like a fridge freezer in your house, eventually something will break. With regards to the sheep, they are generally very good for helping us maintain the site. Every now and again, they'll find a little cable to have a nibble on.

James - Have you had any casualties?

Dan - We haven't Over 200 acres, we've never had a sheep succumb. As a general rule, the sites are generally very good. The inverters are reliable. The modules, considering the sheer scale of it, we don't have to replace as many as you'd think. So on this site, we may replace maybe 10 modules per year.

James - When the sun's not shining, what's the variation in output of the station? And is it fairly consistent year on year or do you have bad years and good years?

Dan - So naturally you will have years that are slightly higher than others, depending on the weather. But as long as the sun rises in the morning, they'll be producing something. Depending on the level of cloud cover, that obviously will reduce - again, it works on solar irradiation. So the more intense the sun, the more efficiently the system will work. So in the middle of winter, if the sun is out and there is absolutely zero cloud, they will still produce a full amount with the sun slightly lower in the sky. But it'll be pretty much there. Obviously, as soon as the cloud cover comes over with the sun a bit low, yes, it will drop, but it still produces more than you'd expect in the winter.

James - Which is probably surprising to most people.

Dan - Yeah, absolutely.

James - One of the things people often say about solar is it takes up a lot of land and this is land that might otherwise be containing lots of wildlife. There's the debate, obviously around people growing crops, food versus fuel...

Nicola - I think operationally as a company, we're very good at looking at sustainability. We compensate 100% of all our operational and travel greenhouse emissions. We always have a plan in place for wildlife, the badger gates, so wildlife can access the sites. Obviously we've already touched on where you can use the land for grazing for grain and food crops. Obviously this is a big space and the farmers decided to graze here as well, which is really great because it benefits everyone.

James - Farmers presumably leasing out their land to a solar farm is a lot less work for them than growing crops. With the war in Ukraine, people are talking about a food security crisis and, at the same time, having this energy crisis and we're pushing for renewable sources to get to our carbon targets. When is there too much solar that could otherwise be used for other purposes?

Nicola - I think farmers have a challenge, wherever they are, to make sure that they're meeting their own requirements. The country's requirements for food sourcing and, as you said, we've got a challenge with energy as well. And I think that they can quite well achieve a blend of that with their land. The solar power is helping them with keeping their farm sustainable from a commercial perspective, but also still being able to use it for grazing as well and for growing the crops that we talked about. So I think all-in-all, it's a good mixture. Obviously you can't just stick a solar farm just anywhere, not all land might be suitable, but similarly, there are also farm lands that aren't suitable for crops either. So that would be a good alternative to help with the energy crisis to use your land for renewables.