Updated: Feb 24, 2020
Knowledge is power and the more you know, the more informed a decision you can make when considering whether a Solar PV Installation is right for you.
That’s why we’ve put together this Jargon Buster guide, to make sense of the most common Solar PV & Battery Storage technical terms.
Take a read through, and if you have any questions at all, contact our team and we'll be happy to help.
The Solar Energy Index
Array – Array is the common term used to describe your arrangement of solar panels. Whether you have two or two hundred panels on your roof, this is your array.
PV – PV is short for Photovoltaic, and our solar panels harness the photovoltaic effect, converting light into electricity. Photovoltaic is the technical term that describes the conversion of light into energy.
AC – Alternating Current. This is the type of electricity we use in our homes and businesses. Every solar panel system uses an inverter to convert the solar panels DC energy, into the more common form of AC energy, to use within the home or business.
DC – Direct Current. Your solar panels generate Direct Current electricity. Though in our homes and businesses we use AC, Alternating Current.
Inverter – An inverter is a key component of your Solar array. Although solar systems don’t contain any moving or mechanical parts, the inverter provides the control and brains behind your system's efficiency. An inverter controls several functions, primarily in converting DC energy from your panels into AC energy in your home or business. A good quality inverter converts energy more efficiently than a lesser one. It’s important to compare efficiency values and warranty periods when considering different proposals.
Solar Panel – A Solar Panel is the key component in generating the electricity of your solar array. Solar panels generate DC (Direct current) and are commonly wired in strings. A string describes multiple panels connected together in series. Each string accumulates the energy generated by each panel and transfers this into the inverter.
Solar Cell – A solar panel is made of numerous solar cells. A Solar Cell is a wafer-thin slice of silicon and is the component within the panel that transforms irradiance into electricity. A solar panel normally comprises 60, 72 or 96 solar cells and are sometimes larger in physical size to accommodate this.
Monocrystalline – Monocrystalline is the purest form of silicon used in the manufacturing of solar cells. Monocrystalline solar cells are made from wafer slices of a monocrystalline silicon ingot (metal) to produce a wafer with an unblemished and very smooth, flat surface. Monocrystalline silicon is considered one of the most important technologically developed materials of recent decades. Thanks to the scale on which monocrystalline silicon is now manufactured, the costs have decreased dramatically over recent years, helping make solar power more efficient, more affordable for homeowners and much more competitive in the commercial energy sector.
Polycrystalline – Polycrystalline, or Multicrystalline silicon, is named so because it comprises multiple different crystals of silicon. It is often melted together to form one larger crystal and thus produces silicon wafers/cells that have a flake-effect appearance. Polycrystalline cells are slightly less efficient compared to monocrystalline but are commonly proportionately cheaper to buy.
Irradiance – Irradiance is a term used to measure the influx of radiation and light. Irradiance is measured in w/m2. Using historical irradiance data gathered by global scientific organisations over many years allows us to forecast the amount of energy a solar array will generate on an annual basis, factoring in the array’s azimuth and pitch.
kWh – There are 1000 watts in one kWh. A kWh is a unit of measurement most commonly used to identify the volume of electricity used in a home or business. E.g. If you switched on a 100w light bulb, it would take ten hours to total the usage of one kWh. Alternatively, if you switched on a 2000w rated appliance, it would take half an hour to use one kWh. Regarding measurement, you will often see:
W = Watts
Kwh = Kilowatt Hour; 1000w per hour
MWh = Megawatt Hour; 1000kW per hour
GWh = Gigawatt Hour; 1000MW per hour
TWh = Terrawatt Hour; 1000GW per hour
kWp – Kilowatt-peak. In the solar industry, we use this term to identify the maximum generating capacity of a solar array. The most common size of a domestic solar PV system has a capacity of 4kWp. This means it has a maximum generating capacity of four kilowatt-hours in standard test conditions. External factors mean a system is unlikely to generate to its peak capacity of 4kWh, though in good conditions it is common for an array of this capacity to generate a kWp of between 3 to 3.5kWh.
Degradation – Solar panels have a lifespan longer than most appliances in the home or machinery in business, this is mainly thanks to its lack of moving parts. Despite their longevity, panels do degrade over longer periods. We term this degradation. All solar panel manufacturer’s warranty their panels against degradation, meaning they guarantee that your panel will perform to a minimum level after 25 years, sometimes longer. When we design and specify a PV system, whether, for home or business, we always factor in the warrantied degradation of a panel into our figures, so you’re safe in the knowledge you’re receiving the full picture.
Base Load – This term is used to describe the items in your home or business that are constantly running twenty-four-seven and usually consists of items you would not switch off. Items that contribute towards your base load are commonly fridges, freezers, alarm systems, WIFI-routers and set-top boxes, to name a few. It is these loads we talk about when estimating a suitable battery capacity for your home.
Azimuth – Azimuth denotes how far from South your roof faces. South is naturally the optimum azimuth for a Solar PV array, though anywhere between the East and West plain is considered suitable for a high level of solar generation.
Pitch – Pitch describes the angle at which your roof faces the sun. The optimum pitch varies up and down the country, though a pitch of between 10 and 50 degrees would be considered more than adequate to generate a high level of solar generation.
Battery Storage – This is the product through which you would store excess energy generated by your Solar PV array. Typically, most homeowners aren’t at home throughout the day when their Solar PV system is generating energy at its peak and they would, therefore, be sending this energy back to the grid. It is here where a battery becomes essential. A battery storage system will store that excess energy generated by your array and keep it to run the home for when you return home at night.
Mounting System – This describes the components we use to mount the system to your roof. Whether it’s a concrete tile, slate, flat or metal corrugated roof.
Export – This is the energy a Solar PV system has generated but is not used on-site by a home or business. It is therefore exported to the grid. If your Solar PV array is generating 5kWh of energy and only 2kWh are being self-consumed, the system would export 3kWh to the grid.
Import – Import denotes the energy a home or business uses on top of their Solar PV generation to meet demand.
Smart Export Guarantee – This is the government's new mechanism to replace the now-defunct Feed-In Tariff’s (See FIT’s). The Smart Export Guarantee became law on January 1st, 2020 and ensures energy generators – including home and business owners, receive payments for all energy exported to the grid.
FIT’s – FIT’s/Feed-in-Tariff’s, are the government's previous method of subsidy. They paid homeowners to generate and export electricity. They were discontinued in March 2019, but replaced by the government’s new flagship payment scheme, the Smart Export Guarantee (S.E.G).
Want To Know More?
These key industry phrases are just a few of the commonly associated terms. Do you have a term you’re unsure about? Get in touch for some clarification and we’ll add it to our list!