Market research and consulting firm, iSuppli has released a report showing the UK as the world’s fastest growing solar market in research looking at solar uptake since last year.

Good news indeed for UK solar and exactly the kind of market reaction which was expected following the announcement of the introduction of feed-in tariffs by the Department of Energy and Climate Change. While the cynics among you might point out that the UK was starting from the lowly figure of 6MW of output in 2009, it in no way detracts from growth figures of 1500 per cent, up to 96MW this year.

Feed-in tariffs, introduced in April 2010 work by offering fixed, guaranteed rates for small scale producers of renewable energy both for the energy they use and the surplus energy fed-back into the grid. The power companies are obliged by the legislation to buy the units of electricity at the top rates, the costs of which are passed onto the consumers.

In areas such as Germany, California and Spain, tariff systems have been an extremely effective way of generating investment interest in new renewable industries, traditionally perceived as unviable. Indeed, the annual Ernst & Young Investment Attractiveness Indices consistently ranks those countries with strong tariff legislation as the most attractive for renewable investors looking for good returns on their capital.

The UK growth is such that it has outstripped that of Spain, a mature solar market whose growth only tipped 730 per cent.

Dr Henning Wicht, Director of iSuppli commented that,

“Things definitely are looking brighter for the solar market in the United Kingdom in 2010, as the country has adopted attractive Feed-in-Tariffs to promote PV adoption. Furthermore, with leading solar country Germany cutting its FITs, the focus of the PV world is shifting to places with more favourable incentives, making the United Kingdom a solar hotspot this year.”

With tariff legislation now in place and growing consciousness of the viability of renewable energy, it is expected that the UK solar market will continue to grow albeit at the more steady rate of 50 per cent. The iSuppli study estimates that the UK market will reach 214MW by 2012 and 501MW by 2014 helping the UK to go along way to meeting its carbon reduction targets and building the foundations of a strong renewable energy industry capable of competing with the like of Spain and Germany.

In the UK’s fledgling PV industry there are some unexpected issues emerging.
One of those is related to the grid or ‘mains’ voltage. This should be, as
in the rest of Europe, fixed at 230V. However it can vary, and in reality
the legal limit is 230V plus or minus 10 percent, generally being higher
voltage close to the nearest transformer, and getting lower voltage as you
move away.

This is important for PV systems because the inverter must convert direct
current into mains compatible AC with an acceptable voltage level. Inverters
are also designed to shut down if there is a problem with the grid for
safety reasons.

In Germany, the voltage level is very precise (perhaps as you might expect)
and since Germany is the world’s largest solar market by far, most inverters
in Europe have their settings with Germany in mind. This means that when the
grid strays slightly away from 230V, the inverter temporarily shuts down. In
the UK, the grid is much more likely to deviate from 230V, meaning that with
German settings, an inverter could well spend more time off than on.

Luckily the problem is generally easily fixed by changing the inverter to
new settings which make it tolerant to a wider voltage range. The key point
to remember is that with the inverter shortage, products are being sold
which are completely unchanged from their German settings. This means you
need to be extra vigilent when buying an inverter to ensure compatibility.

A related topic, that I will soon cover, is to do with how lots of solar
energy connected to the grid can actually affect the grid voltage and
frequency – but that’s another issue.

If an inverter is used in the UK without any change in settings then chances
are, with our fluctuating grid, you will have peaks or dips in the voltage
that shut off the inverter from time to time. The solution is simply to
change the settings via the firmware to allow the inverter to carry on
working in a wider range of voltages.

Understanding how to design a PV system is not rocket science, but it is more complex than many people consider. Here’s a very quick overview of the important points.

Solar panels produce direct current (DC). This means you need an inverter to turn that electricity into mains frequency alternating current (AC).  Inverters come in a range of power ratings. The more solar panels you have, the more power the inverter has to deal with, so the size and cost increases. It’s very important to match the size of the inverter to the number of solar panels.

If the inverter is too small, you will lose out on some of the energy that your system produces. If it is too large, the inverter may not perform at its optimum efficiency, and you will have paid for more than is necessary. In the UK, the optimum situation is to have an inverter that is rated at 80% of the power rating of your PV system, since it is rare you will be producing at 100% power.

More critically than getting the power right, you need to ensure the voltage and current of your solar panel system remains within the input range of the chosen inverter. To re-cap, solar panels on your roof are generally connected together in series, in a ‘string’. This increases the system voltage, but does not increase the current. Once a certain number of solar panels have been connected in series, the voltage will become too high and the system needs to be arranged in two strings, each of the same number of panels, connected in parallel. This generally occurs after a string exceeds 8 – 11 solar panels. When strings are connected in parallel, the currents add-up, but the voltage remains constant.

By adding more and more strings in parallel, the current and voltage can be controlled to remain in the inverter limits. For large solar installations, inverters can used that that have a very high power capacity, or alternatively it is possible to use many small inverters connected in parallel.

It is important to remember certain constraints. Inverters come in several sizes, but there may be some numbers of solar panels for which no inverter is ideal. For instance, because it is necessary for all stings to be equal in size, you can only use an even number of solar panels when using multiple strings. In addition, all solar panels must receive the same amount of sunlight when connected to the same inverter. It is no good to have some solar panels facing different directions on different parts of the roof. New technologies, soon to become widely avaialable that will make this process much easier. Namely micro-inverters, which convert DC to AC at every solar panel, will mean that solar panels can face different directions, however these are not yet widely available.

If you have a sales visit from a solar company, make sure the salesman understands these points as he’s designing your system.

If you want to buy a solar panel in the UK and use it to generate green electricity under the UK feed-in tariff, you will have a much smaller range of solar panels to choose from than customers anywhere else in the world. The reason for this is because of a scheme invented by the UK government called the Micro-generation Certification Scheme (or MCS). This benefits and drawbacks of this scheme were discussed in a previous article on this site and now that we are two months into the feed-in tariff it is a good time for a review of the situation.

There are more solar panels to choose from now than there were two months ago, however there is still a very restricted choice with some major solar panel manufacturers missing from the list. This can only hurt the UK industry. At a time such as now, when the industry is going through an unprecedented boom, customers need as much competition in the market place as possible. Such restrictions are dangerous as they can lead to inflated or irregular pricing. Europe as a whole is experiencing high volumes of demand at present (largely driven by Germany) which is causing equipment shortages and long lead times. We have seen evidence that the MCS restrictions are exacerbating these problems as there is a much smaller number of available suppliers to choose from.

Some of the stated aims of the MCS process are valid. I am very much in favour of protecting consumers from low quality, inferior products. The question remains is how much does MCS add on top of the existing international accreditation bodies for solar panels such as IEC and UL. These bodies are represented by committees with decades of experience in solar panel reliability testing who spend a huge amount of time developing new ways to prove reliability.

MCS accreditation requires visits from MCS inspectors who ‘inspect’ a manufacturer’s facility before their solar panels can be given the green light. Nowhere is it written who these inspectors are and what their qualifications might be to do this above and beyond IEC or UL testing.

Looking at the current list of MCS accredited solar panels it is difficult to see on what criteria certification is being given. Some large very high quality manufacturers are missing, whilst some small, unheard of manufacturers are already there.

I have heard from colleagues in the industry that administrative and beaurocratic issues are currentls holding up a large number of MCS applications and that a raft of new solar panels will join the list soon. I hope this is the case, and I would encourage anyone with more information on the issue to contact this site. My message to the organizers of the MCS process however, is to put more effort into not damaging the industry that it is designed to support.