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Last updated: 13 April 2022

The Ultimate Guide to Solar Panels

This guide is an educational tool about solar energy. It comprises all you need to know when investing in solar power and targets green energy lovers, solar schools, installers, and everyone else interested in joining the 'solar community.'



We’ve been writing and researching for a long time about green energy for and got to the point that everything looks the same. And it can get boring! We thought of this content page that presents all the information you should consider before investing in solar energy, which is easy and fun to read.

You are welcome to have a look at our solar alphabet!


Accredited installer

Even if an installer gives you the best price and best offer, you should first make sure it is an official installer. Having your solar system installed by a non-accredited installer could mean that you are not eligible to apply for the Feed-in Tariff. If you are in the UK, you can check whether an installer is official here: Also make sure that the installer is a member of RECC (Renwable Energy Consumer Code).

Before taking any step

There are some things you should check to make sure that your building is the ideal place for a solar panel installation, such as:

  • Check the size and inclination of your roof.
  • Check your roof’s orientation (S, SE, SW are ideal orientations).
  • Check that nothing will block the sunlight from reaching the panels (trees, other buildings, etc.).

Clouds are not a problem

Contrary to common thought, solar panels work in cloudy weather too. Although it is true that the output will be maximized when the amount of sunlight hitting the panels is greater, solar panels have proved to be significantly efficient in grey weather such as that of the UK.


Some things you shouldn’t do:

  • Don’t sign a deal with a sales person. Make sure an experienced surveyor visits your place and assesses all your needs and building conditions.
  • Don’t clean or fix the panels yourself without checking beforehand the warranty conditions with your supplier. Sometimes the warranty won’t cover if you have touched the panels.
  • Don’t accept a price over the phone, whether a non-binding estimate or a firm quote.


Efficiency is one of the most looked-at features. A solar panel in simple terms consists of a group of solar cells that are grouped next to each other on top of a backsheet and covered by glass. Solar cell efficiency refers to the amount of light that a single cell can convert into electricity and solar panel efficiency is the amount of light that one entire module can convert into electricity. Solar panels currently on the market have an efficiency between 15%- 22%. You might think this is a low percentage, but the truth is, it is enough to power your home and sell some of the remaining electricity back to the grid.

Feed-in Tariff

This is definitely something you should be aware of if you want to make the most out of your investment. Feed-in Tariff is a scheme by the government that will pay you for every unit of electricity you generate, either you consume it, or if you sell your surplus energy back to the grid. Most countries have some similar scheme. If you are in the UK, you can go to to get all the details and requisites to be eligible for the FIT.

Grid-connected systems

When you are choosing a solar panels system, you will see there are lots of options. One important thing to know is that there are grid-connected and off-the-grid solar systems. The first option is good if you want to benefit from the Feed-in Tariff and also if you want to have access to electricity during the night. Off-the-grid systems are more suitable for cottages that have no access to the national grid, and most often go along with batteries to power the house when there is no sun.

Heating or electricity?

Despite the fact that “solar panels” is the most common term to refer to solar power, one must know that solar panels (or solar photovoltaics) are different from solar water heating systems (or solar thermal systems). While solar panels generate electricity and make it available for household use, solar thermal systems are used to heat water, which is then available for heating purposes in the house.


A solar inverter is also called “the brain“ of the solar system. This device will convert the energy captured during the day, from DC to AC, so it can be used for consumption. The inverter combines digital control technology with efficient power conversion architecture in order to make the most of the energy the panels are collecting. You can choose from grid-tie or off-grid inverters. ”Smart inverters” are being developed with forecasting algorithms, load/demand planning and so on. In addition, smart inverters can be “told” whether to use photovoltaic energy or not, send power to batteries to store it, or save you in case of a power blackout.

Ja, Panasonic, Samsung, REC, Sunpower

Are just a few brand names that manufacture solar panels. The major players in the market are competing to bring great features for the consumers such as double sided panels or anti reflective coating. A large amount of resources is invested every year in Research and Development. It is good to have an idea of the different brands in the market, and maybe read a little description of the differences and advantages of each.


You can find it on your monthly electricity bill. They will indicate the amount of electricity you have used. It is always a good starting point to find your energy bills from the last year so you and the solar supplier have a good understanding of your energy use and costs. From this step you can start planning what kind of panels and how many you need. Check with the manufacturer to find out how many kW you can expect the panels to generate.

Long term savings

Solar panels are said to be expensive. And it’s true that the initial costs are considerable (although technological development has lead to an abrupt drop in the costs of solar devices). However, like it happens with any other big investment, one should assess the costs/benefits in the long term. The cost of a solar panel installation can go from £2,500 to £8,000 depending on the type of system chosen. If you are eligible for the Feed-in Tariff, this will payback after approximately 8 years (remember that during all this time you will enjoy the free electricity).

Monocrystalline solar cells

Made from the purest form of silicone, these cells deliver the highest efficiencies. One crystal of silicon is used to make one cell. You can recognize them by the uncovered gaps at the four corners of the cells. apart from monocrystalline cells, you can also choose polycrystalline or thin-film panels.

Normal Operating Test Conditions

(NOCT) are used to measure the solar panel's output under “real world” conditions. This will indicate how much power you can expect the panels to generate on any given day. Initially, the panels are tested under Standard Test Conditions (STC). This is a lab carried test, where the conditions are optimal. However, a solar system will produce lower energy when faced with changes in: weather, shading, irradiance. NOCT assumes the following: irradiance 800 W/㎡, ambient temperature 20°C, windspeed 1m/s, nominal cell temperature 45.7°C (±2°C). So when you read the data sheet of a solar panel, look for the output under NOCT.

Operation and maintenance costs are low

Once the system is installed, you can almost forget about its maintenance. It is recommended to have the system checked once a year by your supplier, to make sure everything is ok. Other than this, you should only check that no leaves or other objects are blocking the panels. A solar panel system is expected to work for at least 35 years.


"Photo" comes from the Greek language, and means "light"; and "voltaic", means electric, and comes from the name of the Italian physicist Volta. Often, solar panels are also called photovoltaics or solar PV’s.


Get at least a few to compare prices of different installers. Also, inquire about how long the work will take and the warranty for their work. Make sure you get binding quotations, preferably in writing. This way you will not have surprises once the work is done.

Rent a roof scheme

Some installers run this business model which consists of installing a free solar panel system on your roof. In this scenario, you rent your roof in exchange of free (and clean) electricity generated by the panel. The catch is that the excess electricity the panels produce will be sold to the grid and the money will be cashed in by the installer. If you decide to get the free panels you should know that you and the installer will enter a 25-year commitment contract. Also, you need to own your home and your roof must usually be 24 square meters due south, or within 35 degrees of south.

Solar energy statistics

Germany is the world's leader regarding solar energy. It has 37.45GWp installed capacity and solar PV accounts for 5.3% of the country's electricity consumption. Second comes China, with 17.7GWp capacity. In the UK there are over 500,000 solar installations, and this number is growing fast. You can check the World Map of Direct Solar Irradiation and see which countries have the greatest potential for solar energy.

Technical information

The solar cell is the main component of Photovoltaic technology and Solar PV systems use these cells to convert solar radiation into electricity. Solar cells consist of one or two layers of a semi-conductor and the most common material used in these cells is silicon, an abundant element most commonly found in sand. Watch how solar panels are made. Solar cells can be wired together to form a module (a solar panel) and these can then be connected together to form an array. More than one array connected together will form a solar system. In addition, a solar panel can weigh from 15Kg to 26Kg, and their dimensions go from 99x140cm to 105x166cm. Moreover, you should know that maximum output (expressed in Watts) is the amount of power a sun panel will generate.

Unlimited energy

The big advantage of solar energy compared with other sources of energy is that the energy of the sun is unlimited. In addition, solar energy is not only a clean and free source of energy, but also a different way to make money. Installing solar panels in your roof will therefore reduce your carbon footprint and also reduce your electricity bills since you will use less energy from your supplier. In addition, if you are eligible for the Feed-in Tariff, you can even get paid for the green electricity you produce. Here you can see a simple explanation of the carbon footprint.

V is for very easy!

Switching to solar energy is very easy once you find the right installer. Finding the right installer is not complicated either. As previously mentioned, you can get free quotes and compare the offers from different installers. You can also ask for references if you have neighbours that have already taken the lead. When you have the installer, it’s just about making the investment and enjoying for the next decades the free and green electricity from your panels.

Warranty of solar panels

Typically, most manufacturers offer 2 kinds of warranty:

  • one for the product
  • one for the output

It is common to get a 10-year material and workmanship warranty. When it comes to output, most manufacturers will cover 25 years. You should check with the manufacturer how much of the output they will actually cover. For example, you could expect 97% of the maximum output in the first year of operation. This will gradually decrease with 0.7% every year reaching around 80% in year 25.



Xavier has a 4kW Solar PV installation at his bungalow, in Bournemouth. The 16 solar panel system generates 3500 kWh per year in green energy. After the first month, he started to save £50 on his electricity bill. After 3 months, the first cheque came in with payments from the Feed-in Tariff- this time £200. Xavier now covers 80% of the electricity he consumes with the help of solar panels. The payback period for this project is 6.5 years but payments from the FIT will come for the next 20 years.

You should get solar panels!

There’s not much to explain here. It is easy, it is good for the environment, and it is also good from a financial point of view.

Zone regulations

Depending on where you live, there might be some planning permissions to consider before making any investment. You should check building permissions in your council to be sure that there are no constraints regarding solar panel installations.

BenQ Solar Panels

BenQ Solar is a division of AU Optronics Company. The company is a leading global manufacturer of TFT-LCD (thin film transistor-liquid crystal display). Their products are primarily used in PCs, monitors, consumer electronics products and televisions. In addition to display panels, the company manufactures photovoltaic (PV) modules and systems for the solar market. In June 2013, AUO launched Power Legato, its first residential energy storage system designed specifically for the European market, at Intersolar Europe 2013. Additionally, AU Optronics completed the first 1.2 megawatts (MW) solar project in South Africa. BenQ Solar claims over 32 years experience manufacturing solar systems. As a total solutions provider, Benq has a complete solar value chain, including: polysilicon, ingot, wafer, cell module and system production. With a workforce of over 32,000 people, the headquarters and production facilities are located in Taiwan. The company is represented all over the world: Singapore, Japan, China, Netherlands, USA and Slovakia.

Canadian Solar Panels

Canadian Solar is one of the world’s top 3 solar power companies, holding 6 GW of modules deployed worldwide. Founded in 2001 in Ontario, Canada, the company quickly became one of the largest solar manufacturers in the world. As a leading provider of ingots, wafers, solar cells, solar modules and other solar applications, in 2011, Canadian Solar reached a revenue of $1,294.8 million. The headquarters are located in Guelph, Ontario, while the company is represented at various locations around the globe: Germany, Italy, Spain, South Africa, India, Japan, Korea, Australia, the United States, Singapore, and China. Manufacturing facilities are currently located in Canada and China. The company employs around 7,020 people.

Hyundai Solar Panels

Hyundai Green Energy is part of the Hyundai Heavy Industries and it has been operating on the market for solar panels for the past 20 years. The Korean conglomerate started as a construction company and became one of the Fortune 500 businesses. Hyundai Heavy Industries is known worldwide for manufacturing of plants, ships, cars, machinery and electronics. The Green Energy division produces Solar Power systems, Wind Turbines and Energy Storage Systems. The company is currently supplying quality solar PV’s to more than 3,000 customers worldwide. Hyundai Solar is heading towards more innovation and improvement, recently establishing an R&D laboratory with an investment of 20 million $. 600 MW of Solar Panels make up the capacity of Hyundai Solar. The power plants are located in Spain, Korea, Turkey, Germany, Belgium and Italy.

LG Solar Panels

LG Electronics is a global leading consumer electronics manufacturer. Their product portfolio covers mobile phones, vehicle components, home entertainment products, appliances, heating and air conditioning products. The company has an ambitious growth agenda, investing $820 million over the next five years in its solar cell research. The solar business unit of LG Electronics just celebrated this year the manufacturing of their five millionth module at the manufacturing plant in Gumi, South Korea. 25 years of research and development has brought LG to the forefront of solar manufacturing. A team of more than one hundred solar researchers are working in LG’s R&D department. At the present, LG Electronics employs more than 85,000 staff at 113 factories worldwide. The company achieved total sales of 36.72 billion euros in the 2012 financial year.

Panasonic Solar Panels

Panasonic is a Japanese multinational electronics corporation headquartered in Osaka, Japan. Panasonic Solar Division is aiming to become the No. 1 Green Energy Company in the Electronics Industry by the end of 2018. In 2012, Panasonic Solar bought SANYO, an established solar panel manufacturer. SANYO was the first manufacturer that produced and commercialized worldwide solar cells made of amorphous silicon. The company claims they have produced over one billion cells to date. Their global manufacturing hubs are located in Malaysia and Hungary. Panasonic is now at the forefront of the industry, investing a lot in R&D and striving for better efficiency for their solar modules. Since 2012, the company is building a “Sustainable Smart Town” in Fujisawa, Japan. A whole urban district comprising of 1,000 homes and shopping centres will have a smart energy structure based on solar PVs.

REC Solar Panels

The Renewable Energy Corporation is a Norwegian company, operating in the market for solar panels since 1998. REC produces silicon materials for (PV) and multicrystalline wafers, as well as solar cells and modules. The business activities are organized into three subdivisions: REC Silicon, REC Solar, and REC Wafer. Manufacturing facilities are located in Singapore. At the end of 2013, the company announced they had produced more than 12 million solar panels.

Sharp Solar Panels

Sharp is a Japanese multinational designer and manufacturer of electronics. Sharp Solar division has been around for over 50 years and they offer silicon photovoltaic cells and even solar TVs. The headquarters are located in Osaka, Japan, and production facilities are currently in Poland.

SolarWorld Solar Panels

SolarWorld AG is a German based designer, manufacturer and distributor of solar power technology and systems. The product range is comprised of solar kits, solar modules, sundecks, inverters, planning and monitoring softwares for photovoltaics. Additionally, the company is engaged in further research and development, as well as the recycling process of raw materials. SolarWorld has sales offices in Germany, the USA, France, Singapore, South Africa and Spain, while manufacturing facilities are located in Germany and the USA. SolarWorld AG employs around 2,073 people. In 2013, the company reported revenues of around $600 million.

SunPower Solar Panels

The company is producing residential solar solutions for the past 30 years. Sunpower is the 2nd largest US solar power maker and holds over 200 patents for solar technology. Currently, the company’s solar panels hold the best energy production record on the market.

Suntech Solar Panels

Founded in 2001, Suntech is a solar energy company engaged in the design and manufacturing of photovoltaic (PV) cells and modules. Suntech’s products are marketed for a range of applications in the residential, commercial, industrial, and public utility sectors. The company prides itself with delivering more than 8 GWs photovoltaic panels to more than 1,000 customers in over 80 countries. Suntech is a strong player on the solar market, also holding contracts with several local governments and companies for the development of large scale solar projects. Apart from the solar panels, Suntech also offers BIPV (building-integrated photovoltaic) products. BIPV can blend seamlessly with the construction and are used to create buildings that are sustainable, functional and visually stunning. Research and development activities are also strong at Suntech. Since 2010, the company entered into a research partnership with the University of New South Wales to further improve the conversion efficiencies of solar cells. Suntech has its headquarters in the Jiangsu Province, China. In the video below, you can see how their headquarters are covered entirely with solar panels. Suntech is represented all over the world through subsidiaries in Germany, UAE, the US, UK, Greece, Switzerland, China, Australia, and Japan. At the end of 2011, the company had employed 17,693 people.

Trina Solar Panels

Founded in 1997, Trina Solar is one of the leading Chinese manufacturers of solar panels and system integration devices (roof racking, DC optimization). Trina Solar has integrated all their supply chain, thus producing ingots, wafers and cells in-house, as well as assembling the solar PV’s. The company prides itself with more than 7.4 GW installed worldwide, a world record in power output. When it comes to innovation, Trina Solar strives to bring new products to the market, currently holding more than 980 solar panels patents. Trina Solar is present in 20 companies worldwide, through its own subsidiaries in USA, Switzerland, UK, Italy, UAE, India, Singapore, China and Australia. The biggest markets for the company are USA and Germany. In total, Trina Solar employs around 14,000 people.

Yingli Solar Panels

Yingli Green Energy Holding is a Chinese manufacturer of polysilicon PV cells, modules and integrated PV systems. The Chinese giant designs, assembles, produces, markets and installs PV systems for lighting systems, mobile communication base stations and residential applications. Yingli has a production capacity reaching 2,450 Mw a year and prides itself with more than 40 million solar panels installed in over 50 countries. This milestone has propelled Yingli to become the largest solar panel manufacturer in the world in terms of production capacity. Operations are carried through a network of subsidiaries located in Europe, America and Asia. Yingli employs over 19,000 people. Additionally, the company is a sponsor of FC Bayern Munich, 2014 FIFA World Cup, men’s and women’s US national soccer teams.

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