Solar PV Panels: Everything You need to Know

Get to grips with Solar PV Panels with our conclusive guide to everything photovoltaic.

solar pv

Solar Panels cover a couple of different technologies: Solar Photovoltaic panels (PV) are used for generating electricity, whilst Solar Thermal panels are used to provide domestic hot water.

Solar PV (Photovoltaic) Panels

Solar PV is used for generating electricity for use around the home. They are a great way of powering energy-gulping appliances such as dishwashers, kettles, washing machines, televisions, and more without using fossil fuels to provide the power. The sun’s energy is free (for now, at least!) and you can expect your panels to last at least 25 years.

Types of Solar PV

The panels are ordinarily made up of either monocrystalline or polycrystalline silicon. Monocrystalline panels are made up one a single silicon crystal, and are considered more efficient than the newer Polycrystalline panels, which are made up of many smaller parts.

Monocrystalline Panels

The Pros and Cons of Monocrystalline Panels

+ Lifespan: Monocrystalline panels can last for around 50 years, outlasting their guarantee of 25 years by 100%.

+ Efficiency: These panels are the most efficient available on the market today.

+ Low cost: The panels themselves make up 60% of the total cost of installation.

+ Energy-efficient production: Fewer of these panels are needed to provide the same amount of power that many more thin-film panels will generate, making production more energy efficient.

+ Heat resistance: Monocrystalline panels are more heat resistant than polycrystalline panels, reducing by 12-15% in high temperatures of 50 degrees Celsius.

- Installation costs: Whilst the panels themselves are not too expensive, the overall cost including installation is rather pricey.

- Fragility: The likelihood of panels being damaged here in the UK is minimal, especially with the protection offered by the safety glass shield. However, branches brought down in storms could pose a threat.

Polycrystalline Panels

The Pros and Cons of Polycrystalline Panels

+ Low cost: These panels are formed in a much cheaper way than their monocrystalline cousins, making their retail price much lower.

+ Low wastage: The environment benefits from the simple formation process.

+ Minor heat resistance issues: Whilst monocrystalline panels are more resilient, the mild UK weather is unlikely to cause any problems.

- Lower efficiency: Due to the purity level of the silicon used, polycrystalline panels operate at 13-16% efficiency.

- Many panels required: In order to generate the same amount of electricity, more poly- than monocrystalline panels are needed.

- Appearance: These panels appear more speckled and blue as opposed to smooth and black.

Thin-Film Panels

Another alternative has more recently entered into the market. This is the thin-film solar PV panel, which is produced much more efficiently, producing lower carbon dioxide emissions and coming with a lower price tag!

The Pros and Cons of Thin-Film Solar PV Panels

+ High solar absorption: This allows for better power generation than silicon panels in all kinds of weather.

+ Lifespan: The panels are guaranteed to last well for 25 years and can be expected to run for much longer.

+ Lower carbon emissions: There is much less waste involved in producing thin-film panels, making them more environmentally friendly than the silicon models.

- Lower efficiency: Traditional panels will produce more power per panel than thin-film, so more of the thin-film panels will be needed to generate the same amount of electricity.

- Uncertain durability: Because the tech is so new, it is difficult to put an exact timeframe on how long the panels will last compared to crystalline panels.

- Lower quality: These panels are cheaper, and therefore can be expected to be of not such a good quality as traditional panels.

Solar PV Tiles

The latest of the additions to the solar PV market is Solar PV Tiles. These solar collectors are designed to sit into the roof rather than on top of it, and some are even designed to blend in with the roof tiles around them.

The Pros and Cons of Solar PV Tiles

+ Appearance: The tiles blend in with your roof and the roofs of neighbouring properties.

+ Two-in-one application: Solar tiles act as both the roof covering and a renewable energy provider.

+ Desirability: The newness and more pleasing aesthetic of solar PV tiles make them very desirable to buyers, and could increase the worth of a new home.

- Cost: You can expect to pay around double the price of regular panels for solar tiles.

- Efficiency: As a new piece of tech, tiles are improving but still aren’t quite as good as solar panels. They are generally around 15-20% less efficient.

- No PV and thermal combinations: Unlike some solar panels, solar tiles are not currently able to provide both electricity and hot water.

I recent years, a number of well-known highstreet brands have begun selling their own solar panels. Whilst the lower prices and ease of access can be tempting, you will have to decide for yourself whether these outweigh the expertise that goes into the more expensive models. Check out our article on IKEA’s offerings to help you decide!

Preparing for Solar PV

Whenever you make a big investment it is best to get all of the research out of the way before handing over the cash. There are many things you need to know before committing to a solar PV system.

Once you have decided to go ahead with the idea of fitting solar PV, you will need to know how to prepare your roof for having the solar panels fitted. It is essential that your roof can accommodate for the technology – you really don’t want your panels to end up on the bedroom floor – so get it checked out professionally if and when you can.

Fitting Solar PV Panels

Once all of the research is out of the way, you can go ahead and get the panels installed. This is usually quite straightforward for an experienced installer, but even the most experienced professional might misunderstand fitting a multi-aspect array. Multi-aspect arrays are those which are installed on different faces of the roof. For example, one may be fitted on a south-east facing roof, whilst the other sits on the south-west side. The two must either be fitted with separate inverters or with a single inverter and dual maximum power point tracing (MPP) inputs. This is to ensure that when one side of the system is receiving no sunlight it does not hamper the performance of the other side receiving all of the light. The premise is similar to that of using a poor quality battery alongside a good battery, where the weaker will reduce the performance of the stronger. The solar PV inverter is an important part of the overall system and is essential for allowing the use of regular electrical household goods with the electricity generated by your solar panels. Solar inverters are specially designed for use with PV (photovoltaic) arrays, featuring maximum power point tracking and anti-islanding protection. Some inverters will operate at a higher voltage than others, but all will work well no matter what the maximum power point (mpp) voltage range is, although some products may be better suited to one PV system than another. Find out which is best for your setup.

For anyone having solar PV panels fitted to their home, the main piece of advice remains the same: hire a professional! There is no good reason not to get the panels properly fitted, especially considering the financial incentives available to those who do so. The Feed-In Tariff is a government incentive which offers payback to those who install renewable technologies to generate their own electricity, and it can offer some significant financial benefits.

Using Solar PV

Getting your solar PV array installed does not mean running out of things to consider. Investing in this technology means signing up for a little maintenance, too. Keeping your solar panels in good working order will mean that over the lifetime of the system you will get all that you can from it, keeping your bills low, and generation and income high.

Restricting Shading

One of the most common disruptions to the best running of a solar PV system is shading. This can come from chimney stacks, telephone poles, neighbouring houses, and trees. By stopping light from reaching the panels, these obstacles will effectively prevent the panels from doing what you want them to do.

It is always best to avoid shading to ensure the best solar PV performance. Hard shading  falling on just one part of an array of solar panels can cause the whole system to generate less electricity. Where hard shading affects an array, the solar panels are actually more energy efficient in overcast conditions with no shading. A 15% level of hard shading can reduce electricity output to less than 5% of what would be expected in full sunlight conditions. Keep trees cut back, and if you don’t really need that old chimney stack then it might be time to bring it down.

Is your roof too shaded? Read more here.

Heating Water

It isn’t only solar thermal panels that are good for heating water. All of the excess electricity generated by solar PV will usually be sold on, but it is possible to harness this energy to power your own immersion heater, therefore giving you hot water without the need for gas.

The Advantages?

+ No need for gas.

+ Lower Carbon Emissions.

+ Feed-in Tariff tie-in.

Snow and Cold Weather

Solar panels work best on clear days in temperatures below 30 degrees Celsius. Cloud cover can cause the panels to cut their generation by around 50%, but the array will continue to provide electricity. Good panels will cope with most of the weather than is thrown at us here in the UK, and shouldn’t be too adversely affected by snow, ice, wind, rain, or sunshine.

The problem that can occur with solar PV and snow is that due to the sky being filled with heavy clouds and snowflakes, the panels are unable to absorb sunlight during times of snowfall. However, because the panels retain heat the snow will be very unlikely to set on the panels themselves, meaning that once the snow stops falling and the sky clears, the panels are able to get back to generating electricity right away. In fact, the snow on the ground can even be beneficial as it reflects sunlight back from the ground towards the solar array.

Fire Risks

There has been some speculation as to the potential fire risks associated with solar PV panels. The consensus is that whilst the panels are completely safe if properly specified and installed, there can be risks where the right measures are not met.

- Installation must be carried out by MCS accredited installers to ensure that the system is properly fitted.

- It is essential that the correct DC isolator switch is used in any solar PV system. Some wrongly specified DC isolators have been known to cause fires in the past, and some manufacturers have been known to alter AC isolators to perform as the DC isolators for PV systems.

- Fire fighters are often worried about entering a house which has a solar PV system fitted due to the risk of grounding via the water and hose. The chances of this happening are in fact minimal, but including a fire fighter’s switch in the system could solve the problem. This would stop any electricity from flowing whilst a fire is fought and therefore reassure the fire fighters.

Maintenance 

Solar panels are largely maintenance-free. You won’t have to top them up with fuel or wipe them down each day, but it is a good idea to keep on top of the upkeep to ensure that you are getting all that you can from the technology. The panels, when properly cared for, can be expected to last up to and sometimes above 25 years, so the nurture really is worth it.

Cleaning your solar PV panels will make all the difference. A little wash down every once in a while will keep any build-up of debris from forming on the surface, ensuring that the panels absorb all of the light they can. Check with your installer to see what they recommend you use to clean the system, or hire a professional cleaning company to do the work for you. Just make sure you hire someone with experience of cleaning solar panels to avoid any accidental damage.

Maintenance checks should be carried out regularly, and the easiest way to tell whether anything is wrong with your system is to keep an eye on its performance at all times. This way you will be able to tell when something is not quite right by the amount of electricity the system is generating.

Image by Bernd Sieker

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