An Introduction to Solar Panels

The majority of investors contemplating the purchase a solar array are looking for maximum production from the installation and this makes perfect sense because the Feed In and Exported Energy tariffs are both calculated on the amount of electricity produced. This is measured in the number of kilowatt hours (kWh) produced per year. The maximum amount of power allowed on a domestic installation is 4kW and a standard installation (roof space allowing) will consist of 16 panels of 250 watts per panel to obtain the 4 kw system. However solar panels now come in different wattages up to 330 watts per panel and so the same output can be achieved using just 12 panels if there are space constraints..

However solar panels over 250 watts in output tend to become more expensive and it is therefore more cost effective to use the standard 16 panel layout if space permits.

At this point it is worth mentioning the possibility of increasing the total kilowattage of the system for high energy users with the available roof space. Systems over 4kW can be fitted with the approval of the DNO (District Network Operator) which in this area is Western Power. The regulation is G59/3 (Commercial) as opposed to G83/3 (Domestic) We have fitted a large number of 6kW, 8kW and 12kW systems in private homes, our record being a whopping 26kW (the client did have a three phase incoming supply). If you think a larger system would be helpful please let us know and we will be happy to make the application on your behalf.

The majority of manufacturers now produce panels in the 250 watt to 330 watt range with LG producing a 300 watt panel and BenQ a 330 watt panel. In addition JA Solar and Hyundai produce a smaller 54 cell panel of 250 watts which is just 1.48 meters in length for limited space roofs. The standard size panel being 1.65 meters long by 0.99 meters wide.

Solar Star Power supply and install the majority of main stream manufactured panels sourced from all over the world including Romag and Sun Solar from the UK. In addition a number of manufacturers are building the Solar Edge optimization system into the actual panels as opposed to using separate optimizers. This has driven down the cost of the Solar Edge system to almost the same price as a single string inverter system.

Types of Panel

Monocrystalline (mono-Si) solar cells are more efficient in bright light conditions and are more expensive than most other types of cells. The corners of the cells look clipped, like an octagon, because the wafer material is cut from cylindrical ingots, that are typically grown by the Czochralski process. Solar panels using mono-Si cells display a distinctive pattern of small white diamonds but this is almost eliminated by applying a black backing sheet of laminate to the panels.

Polycrystalline silicone – multicrystalline silicon (multi-Si) cells are made from cast square ingots—large blocks of molten silicon carefully cooled and solidified. They consist of small crystals giving the material its typical metal flake effect. Polysilicon cells were the most common type used in photovoltaics but because of their bluish tinge are nowadays used mostly for commercial projects.

There are also Poly – Mono Hybrid panels available which have a very high production rate such as the REC (Renewable Energy Corporation of Norway.

Because design plays a huge part in the energy production of an installation we use a sophisticated industry standard computer model (PV Sol) to match solar panels and inverters to the orientation and elevation of a building. If orientation is an issue we may mount panels on both East / West roofs using twin string inverters to equalize the solar effect throughout the day and optimise the supply of electricity. Alternatively if shading from adjacent buildings or trees is a problem we would design a system using individual optimizers for each solar panel to negate the shading effect. We have found the most effective method of minimizing shading is the Solar Edge optimization system. Please see Solar Edge optimization.