Solar FAQs

Knowledge is Power

Did you know…the Sun provides the Earth with more energy in a single hour than the whole world consumes in a year. All we have to do is collect it. If every roof space in the UK had solar panels linked to battery storage, we’d have enough energy to power everything we do, everywhere we do it. We think knowledge is power, so we’ve started building a database of all the things you need to know to make good decisions about your energy future.

We’ll post the answer here.

What is Solar PV?

PV stands for Photo (light) Voltaic (Electric). Solar PV panels convert light in to electricity. Note the word light, not sunlight. They continue to produce electricity on cloudy days. It’s just that their output will be higher, the brighter the light is. This is not new technology – the use of light to produce electricity dates back to the 19th Century.

What does an inverter do?

Inverters change the DC current from the panels to AC current needed for your home and the grid. It’s essential the correct type of inverter is used and that they’re located in the right place. Many installers always put them in the loft, but this can be detrimental to your system. Naked Solar are meticulous about inverter choice and placement.

How do I know you’re selling me the right system?

Our solar team have absolutely zero financial motivation to push particular products because their salaries are not commission based. Cornwall Solar Panels (renamed Naked Solar in 2017) was formed in 2010 by Tony Sampson because he had a passion for green energy and saw that there was a great opportunity to take Solar energy away from the ‘double-glazing style’ hard sell pushy sales approach and offer customers a genuinely informed choice. We’re committed to remaining 100% impartial and can install any Solar PV products on the market. And frequently do – because every home and every business is different.

How do I know I’m using the power from the PV panels?

Your inverter monitors grid voltage and ensures that it is putting the power from your inverter into your system at a slightly higher voltage than the grid. Voltage is best thought of as pressure, the force behind the electric. If the inverter produces a higher voltage when you switch an electrical appliance on it will naturally use the power from the panels first.

How much electric will my PV panels generate?

A 4kWp system in Cornwall on an unshaded south facing roof can generate over 4000 units (kWh) per year. If your roof is East or West facing you’re still likely to generate 3400 units (kWh) per year. The average household in the UK uses around 3200 units per year, so living in Cornwall is a definite benefit! Depending on when and how you use your electric depends on how much impact your PV system will have on your bills. With a bit of information about your electric usage and habits, Naked Solar can produce incredibly accurate bespoke forecasts thanks to their PV Sol modelling software.

How much will I earn?

Naked Solar use PV Sol software to accurately calculate your expected output. PV Sol accurately takes in to account panel performance, inverter performance, shading, roof pitch, roof orientation and your local weather data to calculate how much electric you will generate. We then include these figures and how much money you are likely to earn, based on your usual usage and the amount that will be returned to the grid.

What happens when there’s not enough light?

You will simply draw from the grid in the normal way. But remember, it doesn’t have to be sunny to generate electricity.

What happens if my PV Solar Panels are producing more than I’m using?

The excess energy will be sold back to the grid.

I’ve heard that I’ll need an Energy Performance Certificate (EPC). Is this true?

Yes. Properties are required to have an EPC grade D or above to get the full Feed In Tariff. Naked Solar can check to see if your property has one. If you fall below a D grade, Naked Solar can check to see if adding Solar PV will lift the grade to a D, advise on what other measures might help obtain a D and arrange for an EPC assessment, if required, at a cost of £60.

What size system can I fit on my roof?

Naked Solar use a Professional PV design software package called PV Sol. We can build a 3D model of your property to see which panels will fit best on your roof. There are over 400 panel manufacturers in the PV Sol database and every panel listed has details of the panel’s performance.

Do I need to inform Building Control?

No, leave that to us. Naked Solar are accredited to notify all their work to Building Control.

How are PV solar panels attached to the roof?

On homes, for standard installations, the brackets used fix to the rafters of your roof which ensures the fabric is free from loadings. However, new developments in solar technology now mean you can build your roof entirely out of solar material or solar tiles that look like part of your roof.

Commercial roofs vary in construction and there are many different mounting solutions for every different scenario. At Naked Solar, we’re used to dealing with complex or unusual installations. Test us!

What happens in a power cut?

For the safety of linesmen who may be repairing the fault, your inverter will need to shut down. There are some battery systems that will allow you to have back up power in the event of a power cut. If back up is essential, we’ll be happy to put together options for you.

Who will fit the system?

Naked Solar use their own fully qualified tradesmen. A domestic system team is made up of a qualified roofer, a labourer and a qualified electrician.

How long does a PV Solar Panel installation take?

Home installations take up to two days to install. However, typical installations are finished in one day.

Commercial installations can take longer, depending on the size of the site and the specific requirements of your business.

What is FIT?

FIT (Feed In Tariff) is the government-backed scheme which means your electric supplier (eg EON, N-Power, EDF, Utility Warehouse etc) will pay you for every unit that your system generates, whether you use it or if it goes back in to the grid. More info on FITs is available on the Energy Saving Trust website.

How long will it take before I see a return on my initial investment?

You’ll see savings on bills immediately. Payback of the installation cost depends on many variables including quality of panels and inverters, your local weather conditions, shading, pitch and orientation of your situation. Typically in Cornwall you can expect to pay off a home system in 8-12 years and a commercial system in 6-8 years. After that, it’s like getting free energy for the lifetime of the system (25-50 years with quality panels).

Are there schemes to help me get a solar panel installed on my property?

The FIT (Feed in Tariff) is there to encourage the installation of PV panels as it allows you to be paid for the electricity you generate. For more information, look at our FITs page.

I rent a property. Would I be able to get PV solar panels installed?

You would have to check with your landlord. We’ve installed Solar PV for many landlords as they can benefit from the Feed in Tariff, increase in property value and increase in rent.

I have a thatched cottage – could PV panels be installed on my roof?

There is currently no mounting system to put Solar PV panels on thatched roofs. You may be able to have a ground mounted Solar PV system.

I have a loft conversion – could I still have PV panels installed?

Yes, PV solar panels can be fitted to any roof, even if there is no access to the loft or it is used daily.

What other renewable technologies work well with PV?

Many customers also install heat pumps. These take the small amount of heat in the air or ground and extract it to help heat homes and provide hot water. They run on electric and save huge amounts on people’s bills. They need a very specialist installer like Source Energy. They have a work ethos similar to Naked Solar they’re heat pump specialists and have won UK Heat Pump Installer of the year twice!

Does my property need to comply with any special energy requirements before I can qualify for FIT?

You property needs to meet Energy Performance Certificate grade D or above to get the full Feed In Tariff. Naked Solar can check to see if your property has one. If it’s below a D grade we can check to see if adding Solar PV will lift the grade to a D, advise on what other measures might help obtain a D and arrange for an EPC assessment if required (at a cost of £60).

If your property is grade E, F or G you will still get some FIT, Naked Solar can calculate very accurately how much your return will be to help you decide if it’s worth it or not.

Do I need a south facing roof?

No, Solar PV panels work on light and all roofs have light shining on them. Many customers have fitted east/west facing systems and typically generate around 86% of an equivalent south-facing roof.

How many panels will I need?

Solar PV panels vary greatly in efficiency so one panel may generate 250 watts while another panel of the same physical size may generate 345 watts, therefore it’s not how many panels you need but how much power you need. Domestic systems usually aim for 4kWp which is made up of 11-15 panels, depending on the quality and efficiency of the panels chose.

Has the Feed in Tariff dropped now?

Yes, but the cost of systems is coming down too. So,  Return On Investment for Solar PV remains the same. The Government target is for 8% ROI. However in Cornwall, Naked Solar are still finding domestic system can reach 16% ROI and Commercial systems can reach 30% ROI.


How long do panels last?

Solar PV panels gradually degrade over time. Typically they will lose around 15% of their power over 25 years with some high quality panels only degrading around 2.5% over 25 years. This also varies depending on the quality of the panel. Naked Solar use PV Sol software which allows us to forecast very accurately the impact of any degradation.

The technology is moving so fast, surely it’s worth waiting for new panels?

There are advances in technology, however these are aimed more at using different materials, e.g. hiding PV technology in glass. These advances do not show any progress in efficiency so are unlikely to become mainstream. The technology we see in today’s Solar PV panels is the same technology that was used to power some satellites in the early 70s. There are some small incremental advances but these are not expected to change dramatically at the moment.

I’ve got some shading, is that a problem?

Shading will reduce the power output of solar panels and any panels connected to that panel. Naked Solar can calculate exactly what impact your shading will have with their 3D modelling software PV Sol. Severe shading, like a chimney right in front of panels can also cause some long term damage. CSP will be able to advise you of the best place for your panels to be installed.

I’ve been offered some panels with diodes that stop the effects of shading.

Almost every panel on the market has diodes these days and they don’t completely stop the effects of shading, however they do help.

I’ve been told that I need monocrystalline panels as they’re better.

Monocrystalline panels will give more power per square meter. This might not mean that the panel is better than a high quality polycrystalline panel. There are many, many factors that affect the quality of a panel, this is just one of them and efficiency is only a critical factor if you have a limited amount of space.

Where is the best place to mount inverters?

Inverters are electric and electronic equipment so they’re best off being kept cooler. We usually recommend installing them in a garage, utility room or some models can be mounted outside. We advise that the loft is a poor place to install the inverter as they get very hot and in particular will get hottest on the day you want your inverter to work its hardest. This will reduce the output from the inverter and age its components quicker. We know that installing in the loft is easier and quicker and that the slightly shorter cable run may also have an impact. However, it’s a poor trade off as the extra loss in longer cables is more than offset by the extra production and life that you’ll get from your inverter. Another advantage of having the inverter where you can see it is that you can check that your system is working properly. Inverters have a display that tells you if everything is running smoothly. If this display is in the loft then you won’t know anything is wrong until you get the Christmas decorations out!

How long does the FIT last?

You will get paid FIT for 20 years from the date that you register. You keep the rate from the date of registration with your energy supplier and the rate will also follow the RPI (Retail Price Index) each April, which means your investment retains its value.

Do I need planning permission?

In most cases, no. Domestic solar panel installations are considered ‘permitted developments’ and don’t require planning permission unless:

  • you live in a listed building
  • your home’s in a conservation area or an area of outstanding natural beauty. (Panels are permitted in a conservation area as long as they’re not installed on a wall or roof that fronts a main highway)
  • the panels protrude more than 200mm from the roof. We always fit within this limit.

If you’re unsure about permitted developments, please visit the Government’s planning portal or book a call back and get free advice from us.