A big issue for solar and wind energy is that the power they deliver is not constant. Unlike coal or nuclear power stations which produce a steady stream of power whatever the weather, wind and solar suffer from extreme fluctuations. For wind energy, a drop in wind speed can mean a 90% power loss over a large area in just a few seconds.

For solar energy, there are many different types of fluctuations. In the UK for instance, winter months produce only a quarter of the amount of energy as summer months. Obviously solar energy production takes place only between dawn and dusk, and even during the day, clouds can cause major fluctuations in solar energy output. These fluctuations make it hard for electricity grid operators to really use renewable energy since they need to guarantee power is delivered 100% of the time.

At the moment, because renewable energy makes up such a small component of our electricity generation in the UK these fluctuations are irrelevant. However as the proportion of renewables connected to the grid increases these effects will eventually become more significant. In southern Germany, where solar energy makes up over 4% of the electricity generated and at times represents 30% of the electricity on the grid, energy companies are starting to think carefully about how to use this resource most effectively.

Several can be done to decrease the impact from these fluctuations in renewable energy:

The first thing is to have a strong and efficient electricity grid. This is the case in Germany where energy can be efficiently and almost instantaneously moved from one part of the grid to another. This means that when there is a surplus of energy in one part of the country, energy can be transported at very short notice to where there is an energy deficit. Interestingly, as the amount of solar energy in a country increases, short term fluctuations caused by clouds are “ironed out” as shaded solar panels in one region are compensated for by unshaded solar panels in another.

In addition, as some of you may have heard, there is something called a ‘smart grid’ in development. This term is used to refer to lots of different things but on its most basic level it implies that energy demand can be controlled in some way. This could be very helpful for renewable energy since energy demand can be matched to when there is an abundance of solar energy in the middle of the day.

Another tool that can be used is prediction mechanisms. Using weather forecasting and remote monitoring, the amount of solar energy expected can be predicted. Providing this information to energy companies allows them to use various forms of reserve energy such as gas turbines or hydroelectricity which can be turned on and off in a matter of minutes.

The ultimate solution though, is to find a cheap means of storing energy. This would make all the fluctuations from renewable energy irrelevant. Researchers around the world are busy working on a wide range of different energy storage technologies. One of the most familiar ways of storing energy is to use a battery. Regular alkaline batteries are far too expensive and not durable enough to be used on a large scale, but there is huge number of new types of battery being worked on that could soon bring the cost down dramatically.

Besides batteries, there is a wide range of other technologies in development that could all be used to store renewable energy. Examples of these include; compressed-air energy storage, pumped hydro-electricity, molten-salt, fly-wheels and hydrogen, to name a few. Of course each technology has advantages and disadvantages, but it remains that we have a number of potential solutions for storing renewable energy. So the fact that the sun doesn’t always shine is certainly not a reason not to support solar energy.

The much debated, tweeted, blogged and indeed refreshing government legislation, the feed-in tariff, which is to become reality on April 1 could transform micro-generation from cottage industry to nationwide norm within the next few years according to Steven Harris. Harris, as head of low carbon technologies at the Energy Savings Trust (EST) believes that with the tariff legislation in place, the UK will be in good shape to see a large scale uptake of renewable technologies, something which he believes only a few years ago would have been incomprehensible.

“The poor old cottage industry of renewable energy will not know what’s hit it. People could be forgiven for waiting to install these technologies up until this point, but once the tariff comes in, things could change rapidly,” states Harris who certainly knows how difficult it has been to bring about a change in attitudes towards the viabilty and importance of green technologies.

Harris who along with his colleague Bill Dunstar created the BedZed village project featuring carbon neutral housing in the Surrey commuter town of Wallington ten years ago can easily recall the derision which green ideas were met with at the time. The project which was shortlisted for the Stirling Prize in 2003 highlighted the potential feasibility of sustainable materials and carbon neutral building at a time when such ideas were far from the mainstream. Harris recalls,

“It’s amazing when you sit in meetings now; people are saying exactly the same stuff that was laughed at when we were starting BedZed. Back then, things such as using reclaimed materials, sustainability assessments, local sourcing, having an ecological footprint… they were just not on the construction agenda, let alone the housing agenda.”

With the introduction of the feed-in tariff at the beginning of next month the situation has changed dramatically for micro-generation projects such as BedZed pioneered by Harris and Dunstar. The tariff will offer small-scale generators of green energy guaranteed, premium rates for energy fed-back in to the national grid and will thereby seek to offset the obvious costs involved in installing renewable technologies. With annual returns of £500 expected for households with solar PV installed, the industry is hopeful that the solar industry has the potential to take off with the backing of the tariff.

Steven Harris certainly believes that solar micro-generation could become widespread with the tariff mechanism incentivising investment and see the BedZed project become reality within the next decade.

“Solar technology has really moved forward. In China, it’s illegal not to put thermal solar on your roof, but they have the advantage of a totalitarian state. The fact that they have to manufacture panels for billions of people has really driven down the cost of solar. I know when we first started BedZed, the payback on a panel was around 75 years; now it’s about 12.”

The UK feed-in-tariff announcement has generated a lot of interest in solar energy for homeowners. But what of the interest for organisations such as farms, businesses or local communities?

Some in the press have criticised the government’s proposed feed in tariff plans because they do not offer specific incentives to businesses as well as private individuals.

I would argue that the feed in tariff as it stands applies equally well to enterprises as it does homeowners. Businesses are often able to think longer term about investments. The incentives for installations above 50kW are still attractive for commercial roofspaces, especially if businesses use the electricity they generate for themselves, meaning that installing solar would be a prudent investment to have on a balance sheet. That is not to mention the kudos that comes with being a net exporter of green electricity.

In Germany the commercial rooftop segment of the market is the largest by volume, and with a feed in tariff pricing that now looks rather similar to the UK’s. We may therefore expect that companies start to explore using their roof space for PV. In fact if they haven’t thought of it yet, someone else will soon be approaching them with an offer.

That’s not to say the governments plans are flawless however. The UK is still pitifully behind the rest of Europe when it comes to renewable energy generation and particularly microgeneration.

Still lurking in government policy the ridiculously low target of 2 percent of energy coming from microgeneration by 2020. This is incomprehensible given that Germany is already at 4 percent from solar and other countries like Denmark with biomass gain nearly 40 percent from microgen. Surely this target must be revised!

Speaking as a professional in the global solar industry, the new UK feed in tariff has put us on the radar (a bit). Rather than smirking when I mention the potential for solar in the UK, my colleagues are now starting to take some interest…

You heard it here first. Sources recently disclosed to me that we can expect an announcement from the UK government concerning the feed-in-tariff in mid-to-late January.

You may well be aware that while the government has committed to launching a feed-in-tariff program to support renewable energy, it has not confirmed the value of the proposed tariff yet. Numbers have been suggested, but we do not know the exact price per kWh of energy that will be paid to producers and this is causing significant problems for the UK PV industry when advising customers.

The long-awaited announcement will be closely scrutinized to see whether the UK government is serious about meeting its renewable energy targets. Given that the UK is the last major European economy to introduce a feed-in-tariff program (by a considerable margin) the industry will be hoping that the price set will be strong enough to allow the UK to gain some of the lost ground.