Many people have been asking us when the government will finally announce the size of the UK feed-in-tariff which is a fair question since it’s supposed to come into force next April after all. Unfortunately we’re not able to give a definitive answer, and nor are any of the people we’ve spoken to about it.

The ‘We Support Solar’ campaign has done well to generate publicity around the feed-in-tariff. Now the government has mentioned 36.5 pence per kilowatt hour as a provisional figure, asking for an increase on that of just 10p is a strong argument. Whether the government sees it that way is yet to be known however. Alan Simpson, one of the most active and vocal MPs on the subject believes that the delay in feed-in-tariff decision may be a tactical decision by Labour. For example, an announcement on the feed-in-tariff could be used to boost popularity at a key moment – perhaps even during next week’s summit in Copenhagen.

Alternatively, if both the Tories and Labour believe the feed-in-tariff to be a votes winner, there could well be a bidding war taking place behind closed doors between the two parties right now. Neither party would want to be seen as stingier than the other when it comes to creating green electricity and green jobs. This is pure speculation of course, but if it were true it would be great thing for the UK renewables industry.

The opposite could also be true however. With many households already stretched by their energy bills, the government could be looking to reduce the cost of implementing a feed-in-tariff. It is hard to see them going below the already announced 36.5 pence (it would be better to scrap the whole feed-in-tariff together), but they could be waiting for a moment when the newspapers are distracted by another issue to announce the feed-in-tariff plans.

Hopefully in the near future I’ll be able to write a reaction to a government announcement. Until then though, if you haven’t already written to your local MP asking what they personally have done to support the UK feed-in-tariff then go do it, now!

The whole idea of this feed-in-tariff business is that you earn money by selling units of energy produced by your solar panels. So much so that after 25 years of operation you’ve made your money back and have even turned a tidy profit. This means that in order to know whether putting up some solar panels makes any sense, you need to know exactly how much energy they’re going to produce over the 25-year guarantee period.

Easy, you might say – the calculation is pretty straightforward. You find out the average annual irradiation (sunnyness level) from your local weather station, and multiply by the efficiency of your solar panels and the number of square metres you have. This will give you a nice number and away we go. The only problem is you might be more than 50% wrong because we’ve missed out a couple of variables. Variables such as temperature coefficient, tilt angle, diffuse-light fraction, solar cell type, shading losses, inverter losses, cable losses, degradation, module de-rate factor, mismatch losses, anti-reflective coatings, snow and lightning strikes, to name a few.

Of course there are an infinite number of effects that can influence the output of your photovoltaic system (solar eclipse, anyone?). The question is whether you have considered the important ones or not.

Knowledgeable installers use one of a number computer programs designed specifically to take these factors into account. You type in what type of solar panel you’re using, how many, where they are, what angle they’re tilted at, what direction they’re facing and then press ‘go’. It then calculates the amount of energy you’ll produce each month and even the return on investment if you want it to. Behind these models is actually some physics that describes the behaviour of solar cells under different light intensities and correctly.

The most commonly used model in Europe is called PVSyst, developed at the University of Geneva. This software package contains information on a large number of different solar panel types and is capable of taking into account many of the above listed factors. Installers across Europe use this software package to predict the energy yield of residential solar systems, as do many banks pondering whether to provide multi-million euro loans to super-large PV power projects. Even with this advanced software package however, some of these factors are very complex, and improving these models is an active area of research.

Here, I’ll deal with a couple of these complications as examples. When you buy a solar panel, it invariably comes with a power rating. Full size modules are generally around 200W. What does this mean though? In principle, the power rating indicates what you get when the panel is illuminated by full-sunlight. ‘Full sunlight’ is not very specific, so the international community has defined what is known as Standard Test Conditions (STC), which corresponds to an irradiation of 1000 W/m2 and a cell temperature of 25oC, when the light has a specific spectrum (or colour) known as Air Mass Index 1.5. So the power of your solar panel comes from its performance under exactly these conditions. In general this is measured using special type of lamp called a ‘solar simulator’ that tries to reproduce the AM1.5 spectrum as closely as possible. Calibrating these lamps precisely is notoriously difficult and there are very few testing centers around the world that are truly trusted. The National Renewable Energy Laboratory (NREL) in Colorado, USA uses at least two different lamps and one outdoor measurement to record STC performance, after a long period of calibration.

Because measuring the STC performance is so tricky, the power rating you get has a plus or minus 5 percent error margin. This is hard to include in your simulation. In addition, manufacturers will often deliberately under-rate the power of their solar panels to be sure they don’t fall below the warranty. This means you may well get considerably more power than you expect.

Another factor that adds to uncertainty is the degradation factor. When you buy solar panels they are normally guaranteed for 20 years, but only to 80% of the initial power output. This means the manufacturer expects them to degrade 1% per year on average. When calculating performance in the models, people also tend to use a 1% degradation rate per year. This is only a rough estimate however. During the certification process, solar panels are given all sports of nasty treatment to test their reliability to breaking point. This doesn’t tell you much about the rate of degradation when the solar panels are outside under normal operation though. The only reliable way to test degradation over 20 years is to wait 20 years, but this is complicated by the fact that technology improves reliability much faster than that. So the degradation of solar panels made in 2008 has only been tested since, well, 2008.

What these issues highlight is that understanding the energy yield output of your solar panels is not as straightforward as it may at first seem. When having your system designed, make sure who-ever you’re dealing with has some experience, and if possible, get a second opinion.

The other critical piece of information for understanding the financial viability of a solar installation is how much you will get paid per kWh under the feed-in-tariff. Unfortunately, the UK government has not released the final figures yet, which means no-one in the UK can make a reliable financial plan for getting solar panels, even when the launch date for the feed-in-tariff is just 4 months away.

Hopefully I will be able to update you on this in the near future. For now though, it’s better to be more conservative with your numbers than too ambitious….

The government has recently introduced a new certification program for sustainable energy products. Called the ‘Micro-generation Certification Scheme’ (or MCS), the program is designed to protect customers by ensuring good quality in both products and installation. The scheme works by putting manufacturers and installers through an inspection process in which the applicant has to demonstrate a certain level of competency in the technology they offer, provide a documented, quality management process and show an example of a finished product or installation. In order to incentivize the industry to sign up to the certification scheme, the government has declared that customers may only apply for grants or feed-in-tariffs if their system is entirely covered by MCS which means there is little point in buying an installation without MCS accreditation.

Preventing cowboys from entering green-industry and exploiting customers trying to do their bit for the environment is essential. However, concerns have been raised regarding the real impact of the scheme on customers and regarding the credibility of the certification process itself.

Since this is solarfeedintariff.co.uk, let’s look at the certification requirements for solar energy as an example. In order to claim the UK solar feed-in-tariff arriving next April, you have to install solar panels that have been through the MCS process. At this stage however, few manufacturers have obtained MCS accreditation for their products. In many cases it is simply because they haven’t heard of the UK’s MCS program yet. In other cases, manufacturers who have been told about the scheme may not immediately decide to go for it. To get accredited, you have to pay a private certification center (that in turn has been ‘accredited’ by the MCS administrators) to inspect its product and facilities. This is a costly and time-consuming process. In many cases, someone from the accreditation center has to be flown (at the expense of the manufacturer) to a factory in Europe or Asia so that it can be ‘inspected’ often by someone with little or no experience of the photovoltaic industry. Once you have MCS, the rewards for manufacturers are not clear. In the world of solar energy the UK barely even registers. I am often met with surprise (or worse still, laughter) when I say I’m from the UK at solar conferences. The German market will be over 200 times greater than the UK market this year. There is not a single ground mounted PV power plant in the UK. This means there is no guarantee that investment in MCS will be worthwhile.

The second issue is that certification processes for solar modules already exist. The most prominent is the IEC certification process that can be administered only by a handful or institutions worldwide. This is a rigorous performance and reliability procedure that tests the energy output of a solar panel under controlled conditions, and puts it through a large number of stress tests. These include the damp-heat test (thermal cycling in a humid chamber) and the hail-test (bombarding the module with pellets of ice fired from a canon). IEC tests are designed and continually improved by a committee of international solar energy experts. Wisely, the MCS recognizes IEC accreditation and requires it as part of its inspection. This does lead to the amusing situation where a UK inspector will visit mulit-billion dollar factory that has been supplying solar panels to the rest of the world under the IEC has ‘approve’ that everything in order.

In a photovoltaic system, there are many different components besides the solar panel, however MCS applies only to the solar panel. This is hard to explain. The other expensive part of a PV system is the inverter, which converts the direct current produced by the solar panels into mains 50Hz alternating current so it can be used by most appliances in a building or sold to the grid. The inverter is therefore critical to the good functioning of a system and is known to be significantly less reliable than solar panels which are normally guaranteed for 20 years compared to just 10 for the inverter. Why then is the inverter not covered by MCS?

The MCS for installers in the UK has a clearer role. Many people are familiar with cowboy builders or decorators providing shoddy service, and MCS could be an excellent way to reduce this. Questions remain about the implications for accessibility of micro-generation however. Does MCS mean that a competent DIYer interested in building their own micro-generation system is denied access to government support because they haven’t forked out for an MCS installer?

The main concern is that MCS reduces the amount of competition in the UK, limiting the choice consumers have when it comes to products and installers. Prices of Solar PV systems in the UK are already shockingly high compared to Germany (up to twice the price) and MCS risks being a barrier to entry so that certain manufacturers can now charge even higher prices to UK customers. The MCS could be hurting those it is designed to protect, to the benefit of the manufacturers and installers already within its program.

Certainly the intentions of the MCS are good and with time it could play a key role. The MCS needs to be very careful however not to stunt the growth of the UK solar industry from its current insignificant size. The biggest barrier to that growth is cost, so any measures that may increase costs to the end customer must be rigorously justified.

Labour MP and advisor to the Department of Energy and Climate Change (DECC) Alan Simpson has warned of the presence of an cartel acting against the interests of renewable energy in the UK. At an event organised by Solar Century to promote the government’s proposal of a feed-in tariff system, Simpson announced that there is currently a lobby opposing the renewable campaign headed by the big utility companies keen to protect their own commercial interests at the expense of the development of green energy in the UK.

With the government’s announcement regarding the introduction of the Clean Energy Cash Back system (essentially a feed-in tariff system) in April 2010 much debate has raged regarding the tariff rate which will be required in order to optimise investment in the fledgling UK renewable energy industry.

The feed-in tariff works on the principle that small, renewable energy producers are guaranteed a fixed, premium rate for all units of energy they feed back into the national grid. The renewable energy units are purchased by the utility companies, something which they are obliged to do by the tariff legislation. In actual fact, the government has set a rate of 5p/unit with a subsidy of 36.5p for units of energy generated by small scale solar and wind installations, something which Simpson has controversially asserted will not be sufficient to spark the must needed investment in the industry.

Simpson claims that with the current rate set at 5p, the ROI for solar investors will only be around 5-7 per cent, yields which would possibly not be generous enough to turn the heads of investors who would potentially be attracted by more generous tariff rates elsewhere in the world. With a tariff rate of 10p, Simpson believes that returns could be a more healthy 10 per cent, rendering the UK as a highly competitive market in the world for attracting renewable investment in the long term.

For the UK to finally become one of the major players in the world of solar drastic changes will need to occur within the coming years to catch up with established markets such as Spain and Germany who are currently generating 2,511 MW and 1,500 MW of renewable energy annually respectively compared to the UK’s peak 6MW. Simpson certainly believes that this shortfall can only be remedied with the introduction of comprehensive tariff systems. Speaking at the Solar Century event, Simpson announced,

“Current energy policy in the UK is dominated by the vested interests of “Big Power”. The national grid is monumentally inefficient as an energy system. It was a half-decent idea for the middle of the last century, but 70%-80% of energy put into the grid disappears before you or I even switch the light on. We need not an energy, but a power revolution that takes control from the centre and literally puts power back into the hands of the people”.

Those within the industry back the words of Alan Simpson and are well aware that the future of the UK renewable energy industry is completely reliant on a strong tariff rate. Come April, it will be there to be seen if the government’s rhetoric on tackling climate change can be matched by a determination to take on the big utility companies and drive through a system which will see the UK become a leading light in the green energy revolution.