How Much Solar Can Be Installed On A Roof?

by | Jul 29, 2022

13.2kw solar system

When considering the perfect solar system for your home, you may be wondering just how many solar panels can be safely installed on your rooftop. Should you be more conservative and install a smaller solar setup or cover your entire rooftop with panels as part of a 20kW solar system?

While the answer to this question is different for every household, the different panel capacities can provide some installation flexibility. The capacity in kW of your system is determined by the combined wattage of all the installed solar panels. For example, 24x 275-watt panels and 20x 330-watt panels both provide enough capacity to form a 6.6kW solar system.

This allows different numbers of panels to provide the same effective wattage, offering versatility during planning and installation.

Available Space

The size of the solar system that can be installed on your roof is effectively constrained by the limits of your roof itself. This can shrink even further when it comes to the total functional space. After all, solar panels installed in an obstructed area may not provide enough electricity to suit your household needs.

Factors that can potentially affect available roof space include

  • Shaded sections
  • Obstructions including trees or other buildings
  • Roofs with an unusual pitch

Some of these factors can be minimised, such as using brackets to optimise the tilt of the solar panels, but should be discussed with the professional installers at Solar System.


The orientation of your roof can be an important factor when determining available space for solar panel installation. If parts of your roof won’t be able to consistently generate electricity, they may not be ideal installation zones. The most efficient solar output will be produced using North-facing panels. East- and West-facing panels can provide higher electricity generation in the morning and afternoon respectively but this will ultimately depend on your property and the surroundings.


Physical space is not the only variable when it comes to installing the maximum possible amount of solar. Panels can weigh between 10kg and 20kg each, which can quickly add up if you’re looking at larger setups such as a 13.2kW solar system.

Ensure your roof can comfortably handle the additional weight and pressure solar panels will bring. In turn, this can prevent potential damage to your roof or the removal and reinstallation of your panels.

Electricity Limits

While size constraints may seem like the most prevalent limit, electricity distributors also place restrictions on how much electricity a particular solar system is permitted to generate. These limits depend on the location of your property and the size of the system, from a 5kW to 13.2kW solar system.

Why are energy limits placed?

Due to the way the electricity infrastructure was originally designed, energy was intended to flow in a single direction – a predictable flow to homes and businesses. As such, they are not optimised for electricity to flow back into the grid itself.

As the electricity grid needs to maintain a consistent voltage to function properly, too much energy flowing back could potentially disrupt the performance of existing power stations. Because of this, approval needs to be granted for larger setups, such as a 20kW solar system, ensuring the grid won’t be affected.

In order to maximise the amount of solar energy generated by your system, book a free assessment with qualified assessors from the Solar System. The highly-trained team can assist you with finding the best system for your home and electricity needs.

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