Single Phase Limitations

There’s a definite trend towards larger solar power systems, as people are keen to offset as much of their quarterly electricity bill as they possibly can. However, there are some challenges in doing this if you only have single phase power connected at your property.

Single phase limitations

• Most properties in NSW have single phase power, which means the largest solar power system you’re allowed to install – without being limited by the amount of surplus solar energy you export back to the grid – is a 6.6kW system with a 5kW inverter*.
• With single phase, you can install a system larger than this (eg. a 13kW system with a 10kW inverter), but you can only export a maximum of 5kW back to the grid at any moment in time. This is fine if your energy usage is high and you can consume lots of your free solar energy during the day, but if you’re a smaller user of power or you’re not home during the day to use your free solar energy, it doesn’t really make sense to oversize your system too much.
• However:
  • it IS possible to change some habits, so that you’re self-consuming as much free solar power during the day as possible and by doing this, you minimise the amount of surplus energy that gets capped by the grid. If no one’s home during the day, there are some clever devices (smart relays and solar energy diverters) that allow you to get better use out of your system – meaning you’re less impacted by export limitation (and your electricity bill will be negligible because you’ve run most of your heavy-duty appliances during the day).
    These clever devices – which are cheaper than batteries – effectively turn your home into a smart home by allowing appliances to run only when there’s surplus solar energy. When the sun disappears behind a cloud, appliances that are connected to a smart switch will ramp down. When the sun reappears, they will kick in again Using the example of a pool heat pump, if this hasn’t run for the necessary time or reached the desired temperature by the end of the day, the unit can be programmed to run directly off mains power for a short period to achieve the desired outcome. These smart switches can work with a range of appliances, such as electric hot water, heat pump hot water, air conditioners, pool pumps, irrigation and stock watering pumps, underfloor heating, lighting circuits, fans and garden water pumps.

    Of course, you can choose to just run your appliance on a timer for a given period of time each day, but if there’s cloud cover throughout the day, it’s likely you’ll dip into the grid to run that appliance – and you may still be affected by export limitation.

This is what a single phase meter box looks like: there’s normally only one service fuse installed, and on the meter you’ll see ‘1P 2W’.  

3 Phase Power

When you have 3 phase power connected, you’re much less limited by the size solar power system you install (in fact, you can install up to 39.9kW of solar on a 30kW inverter!) and you can export all of this surplus back to the grid if you choose to.

Some clients opt to upgrade their property from single phase to 3 phase, but this is generally only recommended if you use a fair amount of power/have high electricity bills.

This is what a 3 phase meter box looks like: there are 3 service fuses installed, and on the meter, you’ll see ‘3P 4W’.

Single phase loophole

The current ruling in NSW is that you’re allowed to oversize solar panels to inverter output by up to 133%. ie. a 6.6kW of panels with a 5kW inverter.

However, you can legally get around single phase export limitation by installing SolarEdge optimised inverter solution with a battery (you can’t do this with a string inverter or micro-inverter solution).

With SolarEdge, you can install an Energy Hub inverter of any size (3-10kW), and add up to 3x the inverter rating in panels on the roof!

With the right inverter technology and a battery, you don’t need to upgrade to 3 phase power and you can significantly oversize your system to potentially become completely energy independent. You still get to stay connected to the grid and you get all the benefits this offers, but your electricity bills will shrink to next to nothing 🙂

Sound good? Like to learn more. Send us an email at save@theenergyexperts.com.au or give us a call on 1300 516 474.

* The exception is the AusGrid region, where you can install as large as a 10kW system with a 10kW inverter without export limitation issues. If you’re not sure what region you’re in, you can check out this handy page (just enter your postcode down the bottom and click ‘Electricity’ and ‘Solar’).