A 4 kW solar system using 300 watt (W) to 330W modules would require 12-13 panels.
Each module measures out to 1.6 m2. For a 4 kW solar system, you would require 19.2-20.8 m2 of roof space. This area may change depending on how your roof is laid out. Also, whether or not you may need to use additional tilt frames.
We have this article to know how panels may impact your roof.
In South Australia, the average retail price of a standard solar 4 kW PV system installation is 1.09$ per watt, after government solar rebates. This means that, the average cost of a 4 kW solar system is $4,360.
Solar systems have been getting cheaper over the years. We have seen that prices of solar systems do vary widely. Cost-competitive 4 kW solar PV systems are cheap but have low-end components. Premium options are pricier but use reliable and long-lasting products.
The power output of a 4-kW power system varies. Factors include:
The amount of sunshine is what determines a system’s output. In Adelaide we would expect 4.84 sun hours daily. Multiply 4.84 by system size to get a rough estimate of system performance. We would expect a 4 kW system to generate 19.36 kW daily. To get a more conservative estimate, multiply by 0.75 to account for performance efficiency. Note that energy yields are not accounting for seasonal changes. Energy generated will be higher in the summer and lower in the winter.
To install batteries with your solar PV system, we recommend a minimum of installing a 5kW system. This would make the most out of a battery system. A system of that size would generate sufficient energy to consider storing. As 4 kW is slightly lower than 5-kW, we do not recommend installing a battery. Though you can decide to install a battery system now and perhaps go for a small upgrade in the future.
Click here to learn more about batteries.
Payback period is the amount of time it takes for the system to pay itself off. The payback period takes into account energy bill savings and feed-in tariff credits.
Self-consumption is % of solar energy you use out of the power generated. Keep in mind you unable to self-consume when your panels are not generating solar power, this would be when there is no sunlight hitting your modules. You are able to maximize your self-consumption with the use of a battery system.
Assuming you have 30% self-consumption, you will save $1013.12 annually. This is also assuming the remaining generated power goes towards a feed-in tariff. The estimated pay-back period would be 4.30 years.
Assuming you have 50% self-consumption, you will save $1688.51 annually. This is also assuming the remaining generated power goes towards a feed-in tariff. The estimated pay-back period would be 2.58 years.
Click this article if you want to learn how to calculate pay-back period.
What sized system is right for you? (assuming you are located in Adelaide)