Solar Grid Inverter Monitoring System - Part 1

Solar based power has become an important part of modern strategy for some organisations as they move from carbon based fuel dependence to renewable energy. One of my current projects is looking at a solar power applications for a school that is working towards establishing a carbon neutral power system.

The solar panel array that is currently installed on the school's roof has enough panel area to produce up to 5 kilowatts of electrical power on a sunny day.


Fronius Grid Inverters
 

Three Fronius Grid Inverters

Three Fronius IG 30 grid inverters can feed up to 7.5 kilowatts of power back into the grid, or to the school's AC electrical systems. These high power inverters form the centre of the photovoltaic system, as AC power and access back to the power grid is essential at the school.

Grid inverters are essential for a power system to have mains AC power and photovoltaic power, enabling seamless use of both power sources as a single power source.


The goal of this project is to network the Fronius inverters into a PC system running MS Windows, so that information about the power grid and photovoltaic solar array can be collected for educational and organisational use.



Cabling the Grid Inverters for Computer Monitoring

Inverter, fuse box and Cat5 plate

Blue cables are the serial bus

The three Fronius grid inverters have been mounted on the wall in a way that makes it easy to network the units together.

The three inverter units all have special Com cards, so they can be networked together in a bus type network.

At each end of the Cat5 bus network, special terminator plugs are used to close circuit on the network.

Grid Inverter Bus Network and PC Serial Connection

The last unit has a special data logger card that gives the Fronius grid inverters a data IO port for a computer via RS232.

The data logger card has a DB9 connector, which has been then converted to Cat5 for easy of use in the networking cabinet. 

RJ45 connector in the rack to the Data Logger

The cable run from the DB9 connector on the inverter can be up to 20 metres in length. But for longer lengths of cable, RS232 extenders maybe required. For this example, the Cat5 serial cable is terminated into the network rack in another building.

The Windows PC is connected to the terminated rack connection, which connects back to the Fronius grid inverters with which the Windows PC will be communicating.



For part 2 of this project, I install and setup the Fronius IG access software on the Windows PC.

I will also be explaining the features and advantages that computerised power monitoring can have for an organisation.

Stay tuned.