How PV systems are set up in Schoolgen Schools

The PV system installed at a Schoolgen school consists of  solar panels connected in one or two strings.

The positive and negative terminals of the strings are terminated at the DC side of the inverter, the device which converts DC power produced by the PV system to mains AC power. The AC side of the inverter is connected and synchronised with the local distribution board in the school. The system is grid connected meaning that during daylight hours the system produces electricity for use within the school.

The inverters (which convert direct current into alternating current) used are of the grid-connected type ("grid-tied") and is equipped with an isolating transformer to prevent system "islanding" (this means if the grid electricity fails, the system automatically shuts down preventing solar generation feeding into the mains system and creating a dangerous situation for electricians investigating in the area).

Electricity generation data from the inverter is captured and uploaded to the internet by a purpose designed interface device called the Hot-E box. The Hot-E box is connected to the Schools LAN (local area network), and data is pushed to the remote Schoolgen server where it is converted into daily, weekly, monthly and yearly generation graphs on the Schoolgen website.

Typical circuit diagram the 2kW PV system installed at a Schoolgen school

Figure.1 Typical circuit diagram the 2kW PV system installed at a Schoolgen school. More recent systems use different brands of panels and inverters bu the basic setup is the same.

Students are able to view and download the electricity generation data directly from the Schoolgen website as part of in-class investigations and projects.