A offgrid system for private residence, comprising four buildings for both residential and industrial, choose energy independence over a costly grid connection
Grid connection or grid independence? Today, as new residential areas develop outside the existing national grid network it is an important question to ask. And this is what the owner of this residence has done by choosing to be independent of the grid.
The residence is situated in the Cradle of Humankind north-west of Johannesburg, a known anthropological site where 40% of the worlds discovered human ancestor fossils have been found.
This offgrid system has an 84 kW solar array, 72 kVA power-electronics with a large battery bank of 8000 Ah for extended autonomy. It allows supplying independent power to four buildings and several pumps for water delivery. It includes a generator that is used only for energy backup and has been automatically programmed to start at a certain state of charge (SOC) level.
The PV panels was mounted on high frames providing a well appreciated shaded parking underneath for the offices.
Our variostring high-voltage MPPT solar charge controller provides balance of system advantages not available from any other suppliers.
Our xtender inverter/charger has a surge capacity that can handle three times its nominal power which is a great benefit in systems that has to cope with the start-up of large water pumps. No other device on the market in South Africa has this kind of capacity.
What are the challenges of the project?
One of the main challenges for this offgrid system was the location of its solar array. The area with maximal solar radiation was located 60 meters from the buildings. This long distance between PV panels and power-electronics could have become costly for this offgrid system. By using our variostring MPPT solar charge controllers with high input PV voltage it was possible to use small diameter cables with low voltage drop providing an effective and economical solution.
How about the project?
Choosing an independent energy solution has created a big change in energy consumption. Since its installation this robust and reliable system has made it possible to minimize the use of the generator resulting in massive diesel savings and therefore reducing the carbon footprint. From the beginning, this one has only been used in case of emergencies or to charge the battery bank.