With the increasing prevalence of PV panel based domestic (and commercial) electricity creation; usually from roof mounted modules or panels, I thought I would share some thoughts arising from some research I am doing.
PV panels create Direct Current (DC) electricity. Each panel may create up to 40 Volts DC. The panels are interconnected in series, meaning that the end of the supply cable to the next part of the circuit can have hundreds of volts DC potential. The DC supply cable then is connected to a isolator switch (DC specific double pole). The DC electricity then flows into an Inverter, where it is altered into 240 volts Alternating Current (AC) at 50 hertz. This then enters a smart meter, (sometimes constructed to be part of the inverter package). Sometimes this is all mounted on a timber backboard. The electricity then flows through a double pole AC isolator switch. It is then connected to the internal wiring of the property with a feed back into the supply grid. The smart meter will feed over supply into the grid and calculate the tariff. It will also disconnect the supply from the grid should there be an incoming grid supply failure in order to prevent electrocution of linesmen.
Obviously there is no greater danger of fire from all this as compared to any other electrical installation (if correctly installed and constructed out of suitable components). However, there is a greater fire loading in a loft because of the installation, a greater weight loading on the roof construction ( a cause for concern of earlier failure due to fire damage). Along with the danger of electrocution of firefighters from the live DC supply. Should a fire develop in the loft then the occupier is unlikely to detect it early until the products of combustion are smelt downstairs or seen from the street.
Discussion….. Notwithstanding building codes / regulations; I believe where PV panels are installed on roofs of premises, consideration should be given to the installation of smoke detection in the roof space in order to allow for early detection of incipient fires, especially those caused by high resistance faults?
Comments please?
Sam