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.

As usual, it seemed that the UK was falling behind competitors from abroad from a reluctance to look to the future and fully back green energy through strong legislation. Solar markets in Spain, Germany and Italy to name but a few in Europe, attracted investment through incentive schemes in the form of feed-in tariffs. With the UK government finally introducing the Clean Energy Cash Back scheme in April 2010, it now appears that the financial mechanism is in place to help UK solar investment catch up with more mature markets overseas.

According to many within the industry, the UK now has everything in place to become a player in the global solar market.

“The UK market for solar PV is growing explosively. This is because the FITs [feed-in tariffs] bring a huge new raft of players – the energy users – into the market; broadening it way beyond the traditional energy industry. All renewable power sources are benefitting, but solar is doing best because it is so easy to apply,”

Commented Philip Wolfe, Director of Ownenergy and leading exponent of feed-in tariffs.

With the tariffs working as a means of incentivisation for investors who were once reluctant to invest in what was once an extremely expensive field, the tariffs offset costs and greatly improve the attractiveness of green energy investments. In all countries where tariffs have been introduced there has been a massive uptake in investment with individuals keen to take advantage of legislation-protected investments with healthy ROIs.

With regards to potential for the solar PV industry, Edwin Koot CEO of Solarplaza stated that,

“Having experienced the benefits that FITs have to offer, European countries are now looking to capitalise on the emerging UK market. We can already see signs of this happening for our upcoming UK PV Conference: where 67% of delegate registrations are from international companies, compared to just 33% from the UK.”

However, warning that in the current climate the UK solar PV industry is unlikely to achieve overnight success, Clive Collison of South Facing said,

“It will take time to develop the UK market. Currently there is a lack of knowledge so education of potential customers and businesses is needed. Right now, very few people understand the feed-in tariff system and the opportunities to their full extent.

It took Germany, Spain and Italy three years after the start of their feed-in tariff to reach a substantial market scale. No doubt a similar market development will occur in the UK. That is why conferences like the UK PV Conference are important, to educate the business community and customers and build the business infrastructure. There will be plenty of business for everybody.”

After the official commencement of the UK feed-in tariff on April 1^st we were surprised by the relatively mute response that it received in the UK media. The event did get some press coverage, but the general impression given was that this was just another green initiative, rather than the introduction of a program that has caused a major renewable energy boom in every other economy where it has been introduced.

Since then however, signs have been emerging that there is an ever increasing wave of companies entering this market, and that solar energy in the UK is getting interest from international investors.

As you may well be aware, qualifying for the feed-in tariff requires an MCS accredited installation company. Newly qualified installers have been added to the MCS list every day since April now and the range of companies now offering MCS solar installations is very broad. Some companies are one man, local electricians whilst at the other end of the spectrum are large energy companies such as E.On with thousands of installers, there is a large choice for those wishing to have solar panels installed.

One trend to look out for is the increasing number of professional investors who see an opportunity to make money from the feed-in tariff. By paying for a solar installation on a rented roof or field, investors can have access to the feed-in tariff revenue. Owning the PV system can provide up to 10% annual returns over a 25 year period with a high level of security.

Quite how these arrangements will work is not yet clear. There are a number of ways the contracts between the investor and property owner can be written, and great care to needs to be taken to ensure that all liabilities are covered in the case of a property sale or an accident. Despite this, a number of companies are exploring this type of agreement for the UK, which is already very common in the rest of Europe.

For land owners or property owners with suitable roofs, leasing space for solar panels can be a very attractive option. It requires no upfront investment, generates significant revenues, carries little risk, and improves the environmental credentials of the building. A property owner might earn more money if they own the solar system themselves, but that would require significant initial capital expenditure, something which many companies may not be able to afford.

The feed-in tariff is obviously very attractive to investors as there is little risk. Once you are in the scheme, the payments are guaranteed for 25 years. Photovoltaic systems are generally reliable, so long as you use good quality products. Solar panels are guaranteed for 25 years (to 80% of their power production) and inverters usually for 10 years (you should expect to replace an inverter at least once in the lifetime of the installation). Other than this, the only risk is that the sun will stop rising each day, and if it did, you’d have something a bit more serious to worry about than your profits…

If you would like to invest in a photovoltaic system, or have a suitable roof that you would like to rent, you can contact us for more information.

The 25^th EU PVSEC and 5^th World Conference on Solar Photovoltaic Energy will take place between the 6-10 September 2010 at the Feria Valencia, Spain. Considered to be one of the leading annual conferences in the field of solar PV energy generation, the 25^th EU PVSEC conference will be held in conjunction with the 5^th World conference on Photovoltaic energy conversion.

The ground-breaking Valencia conference will also bring together the 36^th US IEEE PV specialists conference and the 20^th Asia/Pacific PV science & engineering conference in what is expected to be a massive and unique internationally focused forum for solar energy specialists.

Attendees of the Valencia conference will have the opportunity to meet experts fro around the world and discuss potential developments in the field of solar photovoltaic generation. New trends will be discussed with a keen focus on recent innovations in the science of solar PV. The opportunity for networking, exchanging ideas and perspectives and keeping abreast of international PV developments will provide an exciting prospect for anybody involved in this industry.

With subjects of discussion covering Industry, R&D, Policy, Utilities, Architecture and of course, end users, those involved will get a truly global perspective on all the key issues facing the solar PV market now and in to the future. With side events such as Fora, workshops and technical tours, the 5 day event will be sure to provide a wide array activities.

Programme:

• Plenary lectures focusing on the state-of-the-art and targets of PV
• Oral and poster presentations of specific research, development and demonstration projects, PV applications, 
  PV markets
• Exhibition of PV products and services (6-9 Sept.)
• Fora and workshops on present-day PV issues
• Scientific tours and a social programme

For more information on the 25^th EU PVSEC and 5^th World Conference on Solar Photovoltaic Energy please visit: http://www.photovoltaic-conference.com/