If you have started to research solar power systems, you may have come across expandable solar power systems. An expandable solar power system is designed to allow you to increase the number of solar panels at a later stage. You may have enough room on your roof to install a 5kW system (20 x 250 Watt solar panels or equivalent) however your budget may only allow you to purchase 3kW worth of solar panels. If this is the case, you have the option to install a larger solar inverter now so you can add a further 2kW worth of panels at a later stage.
(a) Maximised Solar Power System
- 3.0kW of solar panels (12 x 250W solar panels)
- 3.0kW solar inverter
(b) Expandable Solar Power System
- 3.0kW of solar panels (12 x 250W solar panels)
- 5.0kW solar inverter
As you can see, option ‘b’ enables you to add additional solar panels to your current system after the initial installation.
Expandable solar power system advantages
- There are a couple of reasons why solar companies promote expandable solar power systems
The cost of a solar inverter – The difference in price to install a 3kW inverter compared to a 5kW inverter is minimal. When you take into account the time it takes to install the inverter, commission the inverter so that it connects to the grid, and register the inverter with the energy retailers, this process can be very time consuming. So to install a larger inverter now to cater for an expansion will prevent the double up of installation costs.
Energy Retailers – When a new grid connect solar power system is installed and commissioned, the installer is required to register the system with the energy retailer by lodging a document outlining specific details about the new installation. These specific details include serial numbers, inverter capacity, number of solar panels and other information. When an energy retailer calculates the size of the system, they use the size of the inverter as a benchmark. So if you install 3kW worth of solar panels with a 5kW solar inverter, then the energy retailer will class your system as a 5kW system. Once the solar inverter is installed, commissioned and registered with the energy retailer, you will be eligible for the solar feed-in tariff. The solar feed-in tariff varies from state to state and can also vary depending on what energy retailer you purchase electricity from.
Examples:
- Queensland – If you installed a 3kW solar power system with a 3kW solar inverter before the 44c feed-in tariff cut-off date and you currently receive 44c per kW of solar energy exported to the grid, and you wish to install a larger inverter now to maximise your output, you then will forfeit the existing 44c feed-in tariff and have to re-register your system under the new policy and reduce your rate from 44c down to 8c per kWh.
- Queensland – If you installed a 3kW solar power system with a 5kW solar inverter before the 44c feed-in tariff cut-off date and you currently receive 44c per kW of solar energy exported to the grid, and you wish to install an additional 2kW worth of solar panels, you would not need to lodge any additional documents with the energy retailer and would not forfeit the 44c feed-in tariff.
Conclusion
Considering the above factors, expandable solar power systems are generally more versatile and cost-effective than non-expandable systems. If you have the available roof space, upgrading your solar inverter at the start will allow you to install more solar panels at a later date.