Solar Jargon Buster

AC

AC is the abbreviation of Alternating Current. This is the type of electricity we use in our homes and businesses. Solar panel systems use an inverter to convert the solar panels DC energy into the more common form of AC energy.

DC

DC is Direct Current. Your solar panels generate Direct Current electricity. Batteries also use DC electricity. Though in our homes and businesses we use AC; Alternating Current.

FIT

FIT’s or Feed-in-Tariff are a method of paying for electricity that is sold into the grid. This is how we pay homeowners to generate and export electricity.

kW

There are 1000 watts in one kilowatt.

A kW is a unit of measurement of power. It tells us how much power a device uses (like a light bulb or dishwasher), or how much power a device can generate, like a solar panel. The bigger the number, the more power is used or generated. For example, an LED bulk might use 10W or 0.01kW, whereas a column heater would use around 2kW. A typical single solar panel is around 400W or 0.4kW.

kWh

There are 1000 watts hours in one kilowatt hour; kWh. 

A kWh is a unit of measurement of energy. 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. You will often see these measurements:

Wp

Watts peak refers to the peak power of a panel and is measured under STC (Standard Test Conditions) which are similar to a bright sunny day, hence the term ‘peak’ as this is likely to be the highest output you’ll see from the panel.   Typical panels for the UK market are between 300Wp and 500Wp.

1kWp

1000Wp — domestic arrays are usually between 4kWp and 20kWp, Commercial arrays average between 20kWp and  500kWp and industrial rooftop arrays can be 1000kWp (or 1MWp) or more.

PV

PV is the abbreviation of Photovoltaic. Solar panels harness the photovoltaic effect, converting light into electricity. Photovoltaic is the technical term that describes the conversion of light into energy.

Array

Array describes an arrangement of solar panels. Whether you have two or two hundred panels on your roof, this is your array.

Azimuth

Azimuth denotes how far from the North your roof faces. 

In New Zealand North is naturally the optimum azimuth for a Solar PV array, though anywhere between the West and East plain is considered suitable for a high level of solar generation.

Base Load

This term is used to describe the items in your home or business that are constantly running twenty-four-seven and usually consist 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. These loads help estimate a suitable battery capacity for your home.

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.

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. 

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.

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.

Grid

The Grid , also known as The National Grid or Electrical Grid, is the network of power stations, transmission lines, substations and power lines transporting electricity from where it’s generated to individual customers.

Import

Import denotes the energy a home or business uses on top of their Solar PV generation to meet demand.

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.

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.

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. Each solar cell is a wafer-thin slice of silicon that transforms sunlight AKA 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.

Module (see Solar Panel) 

A module is the name given to each individual solar panel, typically measuring around 1 metre wide and up to 2 metres long, it is a collection of silicon cells that generate electric current when photons (light particles) hit the silicon.

Mounting system

This is the frame, brackets, hooks etc required to hold the panels in place. Various solutions are available to deal with the many situations that Solar PV panels can be mounted in.

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.

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.

ZEV

Zero Emissions Vehicle