We are often asked this question when customers are considering installing solar. The answer is that it really depends…
The main variables are:
- How much roof space you have;
- Your budget; and
- How much your electricity bills currently are.
It wouldn’t make sense to spend $10,000 on solar if your bills are only $250/quarter. Likewise, you wouldn’t fill a roof with solar panels, even if the roof could take 30kW. These examples are just excessive for normal households and it would take far too long to get a return on your investment.
Let’s say you have $15,000 to spend on a solar system, and for this you have been offered a 12kW system with 2 string inverters because you don’t have enough north facing roof space to fit all of the solar modules. In this instance, we’ll assume 6kW will be split across north and east facing roof spaces and the other 6kW will be split across the west and south facing roof space.
This 12kW solar system in Newcastle NSW should generate around 41kWh/day, taking into account directional losses (panels facing different directions due to roof space issues). Assuming a Feed in Tariff (FiT) of 11cents/kWh, self-consumption of 30%, and a shoulder rate of 31c/kWh, we would expect to see estimated savings of $2,550/year. A simple payback period for this is around 5.9 years ($15,000/$2,550).
If you’re able to load-shift into the prime solar sunlight hours, have a home office, or are at home most of the day, then yes it would make complete sense to maximise your roof space. The more of your solar you’re able to consume, the higher your energy savings will be.