A solar PV system looks simple from the street: panels on a roof. Behind them is a short chain of equipment, and knowing what each part does makes it easier to read a quote and to ask the right questions.
Panels make direct current
Each panel is made of cells that produce direct current (DC) when daylight falls on them. Panels are wired together in groups called strings, and the voltage of a string adds up panel by panel. That is why the number of panels in a string matters: the inverter has a range of voltages it works with, and the strings are designed to stay inside it.
The inverter makes it usable
Homes and businesses run on alternating current (AC), so the DC from the panels goes to an inverter, which converts it. The inverter also watches the grid and switches itself off if the grid goes down, which is a safety requirement. Many inverters connect to an app or a web portal, so you can see what the system is producing.
Where the electricity goes
From the inverter, the AC goes to the consumer unit, the main distribution board of the property. Anything switched on at that moment uses solar electricity first. If the panels produce more than the property needs, the surplus goes to a battery if there is one, and otherwise out to the grid. When the panels produce less than you need, for example in the evening, the rest comes from the battery or from the grid as usual.
What changes how much a system produces
Output depends on the amount of daylight, so it changes with the seasons and the weather. It also depends on the direction the roof faces, its angle, shading from trees, chimneys or nearby buildings, the temperature of the panels and how clean they are. In the UK a south-facing roof is generally the strongest, but east- and west-facing roofs also work and can spread production across more of the day. A good design looks at all of these together rather than at any one of them.
What to have ready for a quote
A few photos of the roof from the ground, the type of property and its address are enough to start a conversation. A photo of the consumer unit and the electricity meter helps too. With those, the team can talk about what is possible on your roof and what needs to be checked.
Planning something like this?
Send the address, the type of property and a few photos of the roof by email, and tell us what you would like the system to do. You can read more on the solar pv installation page.