Choosing Your Solar Panels
In this chapter we want to look in more depth at the type of panels available; the importance of choosing a reliable installer and system and how to make effective price comparisons.
As you will have discovered from previous chapters, everybody’s situation - and therefore requirements - are very different, so there is no one system that fits all and neither are all panels created equally.
Although this may seem confusing at first, it’s actually a good thing because it means there’s something out there for everyone’s energy needs, roof space and budget. If you ask a salesman which panels are best he’s going to tell you his are.
So how do you find what’s best for you?
Firstly, you have torealise the question isn’t, “What’s the best PV system?” but rather,
“What system will give me the best value?” Once you know what to focus on, everything gets a lot simpler and you can easily work out the answer for yourself if you,
1. Ask your prospective installer the right questions
and, 2. Do a very simple comparison calculation, which we will get to
soon. The main thing to remember right now is that even though some
panels are more efficient than others, that fact alone doesn’t justify
the extra cost.
First, let’s look at the types of solar PV systems that are available
and what you can expect from them:
Monocrystalline cells are cut from a single crystal of silicon. They are the most costly solar panels to manufacture and therefore the most expensive to buy. They can be up to 50% more expensive than equivalent polycrystalline panels. However they are also the most efficient solar
panels available, with efficiency levels ranging between 15% and 24%.
Their extra efficiency means they are also the smallest solar panels (per watt) available, which is something to consider where roof space is very limited and fewer panels can be used. They come mounted on a rigid frame for protection.
Polycrystalline or Multicrystalline
Polycrystalline cells are also known as multicrystalline and are cut from a block of silicon that has been made up of a large number of crystals. They have efficiency levels of between 13% and 18%. The production process is not quite as complex as that for monocrystalline which makes
them less expensive and thanks to an increase in manufacturing capacity
the price has been dropping at a rate of 25%-30% per year since 2009.
They also come mounted on a rigid frame for protection.
Amorphous or Thin Film
Amorphous cells are also called thin film and consist of a thin film of non-crystalline silicon that can be placed onto a wide choice of surfaces. Due to its amorphous nature it is flexible and if placed onto a flexiblesurface at the manufacturing stage, can be used on architecture that has
curved surfaces. The photovoltaic material is not as fragile as thin silicon crystals and one or more layers can be printed or sprayed onto a flexible substrate and protected by a flexible transparent layer applied in the same way. The result is a much lighter and flexible product than silicon crystal cells encased in glass and mounted using heavy frames. Another benefit of not having to be encased in glass for protection is that the cells maintain a lower temperature becoming more efficient at higher ambient temperatures. They are more efficient in overcast
conditions and can even produce energy from full moonlight. The aim of thin film technology it to allow more flexibility in their application while being cheaper to produce than silicon cell panels.Still, amorphous solar panels are the least efficient, converting a maximum of around 8% of sunlight to electricity. There are a number of different chemistries being used to produce amorphous solar panels and the results are so varied, it’s impossible to recommend them in a situation where you are looking to maximise output and income. While they are the least expensive choice their inefficiency would mean that many more panels would be required too, which would also be a problem where roof space is limited.
Solar shingles are PV cells that are designed to look like regular asphalt tiles while still being able to capture sunlight and convert it into energy. There are a variety of designs but they generally come as shingle-sized panels in strips of about 300 x 2,200mm (12 x 86 inches) that can be
stapled directly to the roofing felt. Usually they can be interspersed with regular asphalt shingles but different models require different mountings and installations. Once in situ, their dark blue-purple colour and the fact they look, in most cases, similar to existing roof tiles make them a favourite with those concerned about aesthetics. Solar shingles may be designed differently to amorphous panels but they use the same technology as thin film panels which means, when it
comes to getting the maximum output in order to benefit from the Feed In Tariff, the same problems apply.
Calculating The Best Solar Value
When you receive quotes for your solar panel system you may be surprised how much they differ. After all, you made sure that they were MCS accredited installers providing the big brand named systems and gave the companies the same details to work with - like your energy needs, your roof space and your budget. So why has one come back witha quote of £15,000 and the other £20,000? Has there been a mistake? Is one of the companies trying to rip you off? The chances are, they are both giving you the best deal they can. To find out, you need to ask:
“How much energy in kWh each system expects to produce in the first year?”
Once you have the answer to this question, you can divide the cost of the system by the amount of energy produced and this will give you an idea of how much money, per kWh, you’ll be paying and you’ll be able to choosethe panel that produces the most kWh at the lowest cost. For example:
Checking Out Solar PV Products
The MCS have been given the responsibility of approving solar panel products and installers by the Department of Energy and Climate Change (DECC). As we have mentioned before, if you want to be sure that you can earn money from the Feed In Tariff scheme you need to use installersand products that have a certificate of accreditation by the MCS.
You can reduce the true cost of solar panels by using quality solar panel information websites providing information and access to the best MCS accredited solar energy installers and products.
To understand the efficiency of a specific solar panel that you are considering you can find efficiency statistics at the following website:
Frequently Asked Questions About Choosing Solar Panels
Q: Should I be looking for the panel that has the highest efficiency or one that produces electricity at a lower rate?
A: The highest efficiency rate is most relevant where roof space is a
concern because you must make as much energy as possible with fewer panels. However, in most cases it will be the cost of the system that will be the greatest consideration. So choose the panel that produces the most electricity (kWh) at the lowest cost.
Q: Can solar panels be attached to flat roofs?
A: Yes. An ‘A’ Frame will be used to angle the panels at between 20 and 50 degrees from the horizontal position, depending on what angle is requires at that location.
Q: Will a solar system add value to my property?
A: Yes. In fact, a recent MORI survey revealed that people were willing to pay up to £10,000 more for a home built to high energy efficiency standards and, as a result, estate agents have
been raising the value of properties with solar panels.
Q: Is there really enough sunlight in the UK to make solar energy a feasible option?
A: The UK receives just over half the energy found at the equator, which is enough to operate a highly efficient solar panel system from a south facing roof, even in the cooler northern reaches