What is it Solar PV and how does it work?

‘Photovoltaic’ is a combination of two words; ‘photo’, Greek for light, and ‘voltaic’, from ‘volt’, meaning electrical power.

The solar cell is the main component of Photovoltaic technology and Solar PV systems use these cells to convert solar radiation into electricity. These 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. Solar cells can be wired together to form a module (a solar panel) and these can then be connected together to form an array.

 

How do solar cells produce electricity from light?

Essentially, when light shines on the cell it creates an electric field across the layers causing electricity to flow. The more intense the light is, the greater the flow of electricity. However, PV cells produce electricity in the form of direct current (DC). An inverter is needed to covert this electricity to Alternating Current (AC) which can then be used in your house and exported to the national grid.

 

A typical grid connected roof mounted system consists of a number of components, as shown in the diagram below:

 

The main components in a Solar PV System Solar cells

Solar cells and modules

These are used to capture the suns energy, initially supplying Direct Current to the system. We are able to offer a choice of industry leading solar panels made by ‘Solarworld’ in Germany.

Inverter

An inverter is used to convert direct current (DC) electricity, from the solar panels, into an alternating current (AC) which is then fed into the electricity supply for use in the building and for exports to the national grid. We supply and fit industry leading ‘SMA’ inverters.

Solar PV mounting system

A mounting system will be needed to accommodate the PV system.

Generation Meter

Every AC unit (kWh) generated from the system in counted up on the generation meter. This meter defines the amount you receive from NIROCs.

Consumer Unit

Also known as the ‘fuse box’, this is the main point of connection. Solar PV provides the primary source of electricity, however, if more is needed the grid will supplement. In contrast, if there is excess electricity, it will exit to the grid.

Isolators

Isolators enable separation from and within the PV system for safety when carrying out installations, upgrades and maintenance work.

Cables & Connectors

Used to connect the various components of a PV system and are selected based on the size and characteristics of each PV system.

Remote System Monitoring – Optional

Remote monitoring can be provided so you can you track the amount of electricity the system is producing, how much is used within the property and how much is being exported back to the grid. This can be carried out by most commercially available inverters and can be integrated into PC and web applications or hand held devices.

Import/Export meter

Like a conventional electricity meter, it counts up usage, but it also defines the amount of export the Solar PV system has added to the grid. NIE will replace your existing import meter with a import/export meter after your Solar PV system is installed and commissioned.

Types of Solar PV Panel

There are 3 basic construction types of Photovoltaic solar panels:

Crystalline – Monocrystalline Monocrystalline

Monocrystalline cells are cut from a single crystal of silicon and are the most efficient type, but also the most expensive to produce. They are completely rigid and must be mounted in a rigid frame for protection.

Polycrystalline

Polycrystalline cells are made from a slice cut from a block of silicon that consists of many crystals. Solar PV panels made from these types of cell are slightly less efficient but also cheaper than monocrystalline cells. They also need to be mounted in a rigid frame.

Thin Film – Amorphous

Amorphous cells are manufactured by placing a thin film of non crystalline silicon onto a wide range of surfaces. This creates the least efficient type of PV panels but also the cheapest and if manufactured on a flexible surface, the whole PV panel can be flexible. One problem with amorphous cells, however, is that their power output reduces over time, particularly during the first few months, after which they become stable.