How solar PV works

Solar Panels.
Solar cells are made of semiconductor materials, traditionally silicon, which is also used in the microelectronics industry. Silicon is highly resistive and so it needs to be specially treated with specific impurities, these with less tightly bound electrons, in order to create the specific properties of a dielectric material. This forms an electric field, positive on one side and negative on the other, across a thin wafer of the material. When photons (particles of light energy) strike the cell, electrons are knocked loose from the atoms in the semiconductor material. Electrical conductors attached to the positive and negative sides and also to a load, such as a lamp, or inverter (see below) form a closed electrical circuit, through which the electrons can flow. In doing so, useful electricity is generated, in the form of a direct current. 

Inverters.
Direct current (DC), is the same type of electricity as you would get from a simple battery, all the electrons flow in the same direction and at a constant rate. In order for most domestic appliances to use this electricity, i.e. those appliances with AC motors or transformers, it must be converted to 50Hz, 240V AC (alternating current). The conversion is  performed by a piece of equipment called an inverter, which is normally located as near as physically possible to the installed solar panels, for instance, within the loft space. The inverter unit must be carefully specified for each individual installation, in order to maximize system performance over a range of conditions, including input and demand. Your surveyor will ensure that the best inverter is selected for your particular installation, dependent on the many factors involved.

Do clouds affect generation?
Solar PV arrays require daylight to generate energy, in the form of electricity. However, they do not require direct sunlight, they can work quite adequately in diffused light, i.e. under clouds/mist etc. and so electricity is still generated even on a cloudy day. Of course, they will not work when in a hard shadow caused by  buildings, trees etc., so their placement is of vital importance to their overall performance. The best conditions for generating solar energy would be a sunny day, but even on a cloudy day, they will generate satisfactory and adequate levels of energy, if the installation’s specification has been computed well.