Times are changing with the fall of solar feed in tariffs and ever-growing electricity prices. Larger solar systems, batteries and EV chargers are becoming the standard for most new homes. With these technologies, comes different considerations for electrical design. We want this document to help make the right decisions for Products, Design and Locations.
Solar Energy Meter
This is separate to the retailer’s meter and is installed on every site with solar (with and without batteries), this device monitors the whole sites imported and exported power to send commands to the inverter. This must always be installed up stream of any appliances that want to be covered by the solar system. The best design is to have this installed in the meter box but can be difficult if the meter box is free standing and not attached to the house. A conduit for a control cable should be considered so things like electric gates, garden lighting etc are not left out. A three-phase meter requires 3-4 poles.
Backup Contactor or Gateway
A battery systems backup capability takes place where ever a contactor/gateway is installed. At this location there is normally a separation of Backup and Non-Backup or Essential and Non-Essential loads. Typically, with most new builds this contactor would be installed in the customers meter box or in their sub board. A three-phase backup contactor will take up 6-8 poles. Some brands offer a “Gateway” that are a medium sub board design with the contactor and energy meter incorporated. There is some spare din rail for additional circuit breakers (cannot be flush mounted). If the brand uses a gateway as the backup/energy control, it is advisable to keep as close to the main switch board as possible.
Solar Inverter and Battery
Solar battery systems can come as a hybrid inverter with a separate battery or as an all-in-one unit. Solar inverters are more resilient than batteries, but the best design is to have them installed as close to the meter box as possible. Inverter supply cables are allowed a 2% voltage rise from POS to the inverter. Normal electrical circuits are allowed 5% voltage drop from POS to the final sub circuit. The further the inverter gets away from the POS, the cable sizes and costs dramatically go up.
Batteries are quite hard to find suitable locations. Not all batteries are IP rated, most of the batteries need to be kept within 5m of the hybrid inverter, clearance to other appliances and exclusion zones to habitable areas (Ref AS-5139). The solar supply circuit breaker is normally located downstream of the contactor and requires 3 poles for a three-phase inverter.
Summary
All this equipment requires lots of room in the meter box or sub board, three-phase systems require 13-15 poles. When the design is out of our control, remote meter box, etc. The sub board gets quite busy as shown in the first picture, this is not even including the energy meter. This results in the customers electrician installing either a much larger sub board or multiple sub boards.
Our preference is to install all our equipment at the meter box, this ensures all loads are captured by the energy meter, we have clear segregation between essential/non-essential loads and we will not need to re wire the sub board that has been freshly wired by the electrician. We will supply a backup main isolator for the electrician to connect loads or submains to.
For any questions regarding this document please contact
Callan Waye 0430 019 293
