Dr. Derek Taylor talks about advances in wind and solar power over the last 50 years.
Interview with Dr. Derek Taylor
Dr. Derek Taylor established the multi-disciplinary practice Altechnica in 1990, and is behind the renewable energy course offered by the Open University. He has also written a talk called ‘Riding the wind and sun for 50 years.’
“Solar and wind were the most important stuff”
Derek worked on the Milton Keynes solar house in the 1970s. The question of how to generate enough energy in the winter led to him researching wind energy, which he found provided what was needed at that time of year. Wind and solar complemented each other perfectly, and that changed his career.
Photo by Bill Toomey
Wind and solar have thousands of years of history
It’s thought that a wind power device was first deployed in about 2000 BC, probably in China. Similar windmill-type devices were developed in Persia as well. Harnessing solar energy might also have begun in China, and we know the ancient Greeks looked at passive solar design when orienting their streets and buildings.
The Dutch are famous for their windmills, and had a host of different industrial uses for wind. Dutch engineers helped to establish windmills in East Anglia, and much of the innovation then happened in Britain.
Solar PV started out prohibitively expensive
Its only original application was on spacecraft! When Derek started out in the 1970s, solar power was too expensive to really think about. The German government wanted to support more renewable energy generation. Combined with technology development in Australia, it created enough of a market for manufacturers to invest in production. China is now the dominant producer, but there are also specialist companies, including in Britain and Europe.
How do solar PV panels work?
Panels are a combination of two layers of material which are ‘doped’, one to be positive and one to be negative. Light shining on the panel excites the electrons so they move through the system. That movement is captured with wires to generate DC electricity.
For domestic appliances, the DC needs to be converted to AC through an inverter. In the early days, inverters were expensive and prone to problems. Now they’re more cost effective, and can even be sited on the actual panel. But if you want to charge a battery then you need DC!
There is lots of interesting solar PV technology
Most of the technology is based on crystalline silicon, where a single crystal is grown and sliced into wafers. There is also amorphous, thin film solar which has never really been successful – it can be used in windows, but it doesn’t produce a lot of electricity.
Particularly interesting is combining multiple layers of solar cells tuned to different parts of the spectrum. You can generate more energy that way.
The UK has a lot of solar resource
A typical roof area will generate the average electricity requirements in a year, so it's in the right ballpark. South-facing roofs are normally optimum, but an east-west arrangement can work well. With the falling cost of solar, sometimes east-west might be the more interesting possibility because you can get morning and evening power production.
What should you look for in a PV array?
Good durability is an obvious starting point, and the peak power output should be as high as possible. Maximum efficiency is more important where you’ve got a constrained area. If you have space then you can cover a larger area with lower efficiency panels, which will be cheaper. It depends what your energy demand will be.
Overall, it makes sense to cover as much of the roof as possible, because the price of electricity is unlikely to go down soon.
What are the best uses for solar PV?
People talk about using PV panels with heat pumps, forgetting most electricity is generated in summer when the heat pump is mainly needed in winter. There's a bit of a disconnect. It makes sense to use the electricity generated for electrical purposes, although you could use it with a heat pump in the warmer months for hot water.
Solar PV panels can be expected to last for at least twenty years
Efficiency will degrade over time because of wear and tear, especially due to the weather. Installations need to be protected from high winds. Overall, though, there are few moving parts so panels should last a long time, and that makes them a sensible investment.
Batteries are becoming an interesting option
For a long time they were very expensive, but have followed the same cost curve as PV. When people are out during the day the battery can store the generated electricity for use in the evening. It’s possible to use excess electricity with an immersion heater, but it's quite a high-tech way to heat water.
Solar water heating panels are also an option
They will produce sufficient hot water for about three quarters of the year in the UK climate. However, a lot of washing machines don't allow you to plumb in a solar water heating panel.
Roofs may not always be the best place for PV
Roofs do make sense, but installing and maintaining them requires scaffolding and roof workers. If you have the land area, having PV nearer the ground – on a carport, for example – is appealing from a long-term perspective.
Derek would like to see solar canopies over large car parks, which would make use of otherwise ‘wasted’ space. It would have the added benefit of protecting the cars parked underneath from the weather.
Solar farms on agricultural land could also benefit from raising the panels above the ground by a couple of metres. Enough light comes through to grow the crops, while also protecting the crops in summer. And the transpiration from the plants can help to cool the panels, so it’s a win-win.
To give an idea of the scale we’re talking about, more agricultural land is taken up by golf courses in the UK than would likely be needed for solar.
Solar is probably the best choice for return on investment
For domestic use, electricity is the most expensive form of energy, although that's changing as more renewables come onto the grid.
Gas is going to be phased out, so what we do about heating is the big issue. Rather than making individual decisions, we need to think about community-scale and neighbourhood-scale projects. Some technologies only make sense at that kind of scale.
In Denmark, for instance, 65% of houses are heated from waste heat from power stations or district heating systems. It’s a much smaller proportion in Britain, because of various policy challenges over the years.
Land-based wind turbines are probably the cheapest form of electricity generation
However, it’s almost impossible to install a wind turbine on your land because only one objection can stop a project. That’s a result of government policy.
The advantage of wind turbines is that they can be built with standardised components produced in volume, which helps with costs. The largest turbines at the moment are around about 16 megawatts, with blades over 100 metres long – longer than the wingspan of a jumbo jet.
Land with wind turbines can also have a second use
Compared with solar PV parks, wind farms are even easier to assign a second use because the footprint of the wind turbine is only its base. Most animals seem to cope very well. An animal shelter project in Cambridgeshire installed its own wind turbine and the horses and animals were fine.
Community-level wind schemes in Britain are difficult
Mainly for the reason that most available sites are used by commercial companies. There are organisations trying to make schemes happen, but funding is needed in the first instance for feasibility studies. In Denmark, about a third of projects are owned by cooperatives and local people. But the expertise is rarely in the communities, so you need to work with people you can trust.
The West Mill Wind Farm cooperative in Oxfordshire has five turbines, and a solar farm as well. But that took seven years of hard work to get it off the ground.
Photo copyright Westmill Wind Farm Co-op
There could be no limit to wind power
Britain is well set up, having a shallow seabed around our continental shelf. Floating wind turbines are an interesting technology too, because you can go into deeper water. We have a lot of resource around our coast for seabed and floating turbines – equal to Gulf oil reserves every year, potentially.
At the start of the 1970s there was zero electricity going into the grid from wind energy. Now, it produces about 26% of UK electricity, and as much as 30% in January. It’s been a real success, and there’s no reason why it shouldn’t continue.
Energy storage is quickly becoming the issue
Wind tends to be dominant in the winter months, and sun in the summer months. Wind blows at night too, which is another interesting benefit. The two energy sources are complementary, but if we’re going to have more of both then we need systems for when the energy is not available. Energy storage is becoming more and more important, as well as backup systems. In general, batteries can work overnight but not for much longer, so we need other technologies to be deployed.
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