Is Solar to blame for high grid voltage?

Yes in some cases, with a big impact for the electrical network.

Solar systems can play a positive or negative role in our electrical grid’s stability, so as long as a Solar system designer stays within the rules then a balanced, cheap, and renewables + storage dominated grid can be built for the future.

The Solar industry is governed by the Clean Energy Council and Australian Electrical Standards however, a large proportion of Solar system designers do not train for any CEC qualifications and instead defer the electrical design responsibilities onto the installation crew.

Grid connected Solar systems are entitled to a set level of ‘grid export’ for leftover Solar power that the building does not use, and this varies due to 3 different factors. The starting point for any design should be the Voltage Rise Calculation or ‘VRC’. (AS/NZS 4777.2 2020). By placing an unrestrained Solar inverter on long and/or thin wires traveling back to the transformer the grid shared voltage can be raised up high, and this risks the Solar inverter performing poorly, shutting down, or in the worst cases it can damage your buildings appliances.

We recently dealt with a client in the Thora valley who was quoted by another company and they had apparently “lodged an Essential Energy grid application” and were “approved for 5kW of export”, but the Solar designer had ignored the VRC (or the cabling was inspected correctly) because we calculated the correct limit to be 3.7kW and installed the system accordingly.

Shortly after installation the inverter signalled (through its online monitoring) that the voltage was getting too high, so the high voltage network was already at the upper limits before the Solar was even installed and the client’s water pressure pump was damaged.

The key to this story is that because we had kept within the ‘VRC’ rules we were able to lodge a complaint on behalf of the client with Essential Energy to rectify the grid voltage (re-tapping the transformer), and the pump was repaired at no cost. Had the higher export level been implemented then the voltage issue would have been blamed on the Solar system with no chance of fixing the issue.

To ensure that your Solar & Battery consultant (not the company) has a design accreditation with the Clean Energy Council then check by surname or location @ CECfindaninstaller

Geoff Tosio – Better Volt Solar + Batteries, based in Dorrigo.

0422 544 555