Solar Electricity - Solar PV

Solar panels are available in two main types – solar PV (for electricity), and solar thermal (for hot water). This section talks about solar PV (solar photovoltaic).

Solar PV panels convert daylight directly into electricity. They do work when it’s cloudy, but, prefer direct sunlight. One solar panel is unsurprisingly called a “solar panel”. When you add lots of panels together then that’s normally referred to as a solar array or solar PV array.

Each panel in the array is connected to it’s neighbour in series to form a long string of panels. One or more strings are then connected together and all the power from the whole array is fed into just two wires. Solar PV panels create DC current. Houses and the national grid run on AC current, so, these two wires connect to an inverter which changes DC to AC. In most cases the PV array will be grid connected. To connect to the grid the inverter is connected to the consumer unit via a spare circuit breaker. This then allows you to either use all that you generate yourself, or, feed surplus back into the national grid.

Solar PV arrays need more space than solar hot water. Typically an average solar PV array on a house would take up about 20 square metres (the minimum required is 12sqm). Also solar PV arrays are more affected by shading. If just a few panels are affected by shade it will not just affect the power output of those panels but will reduce the power output of all the other panels in that string which could be up to 12 panels. Therefore it is important that panels are positioned in an area that is unshaded where they will be in full sunlight for the lion’s share of the day.

In order to benefit from the maximum amount of sunlight available, arrays need to be positioned in a southerly aspect (south west through to south east). For a roof sited array a mounting system is attached to the existing roof on top of the roof tiles. This is referred to as a roof mounted system. The panels will typically protrude above the roof no more than 14 – 18cm which is within planning guidelines of 20cm. A panel array that lies flush with the existing roof is known as a roof integrated system. This involves a section of the existing roof tiles being removed and the panels fitted in their place. This system typically costs more than a roof mounted system but can be cost effective if you need to replace sections of the roof.

Little or no ongoing maintenance is required. The panels need to be kept clean and generally rainwater does that very well and just remember to keep any trees etc. that could cause shading cut well back.

To know how much energy your Solar PV system is generating you will have your own Naturalwatt webpage (your MicroGrid) that will display LIVE the amount of energy generated and amount of CO2 saved.

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