What is Solar Export Limiting?

Fast read

Solar export limiting controls the amount of electricity solar systems send back to the grid.

Introduced due to Australia's high solar system adoption rate, it ensures grid stability by preventing excessive solar electricity from causing voltage and frequency surges, which can damage infrastructure and appliances. Typically, systems might be limited to exporting 5-10kW, with some areas allowing no export.

This might initially seem restrictive, but it allows homeowners to install larger solar capacities without impacting the grid. It also boosts the value proposition for adding batteries, allowing for storage of excess energy for later use. Overall, export limiting safeguards grid stability while supporting continued solar adoption.

It is also a sign that the policymakers responsible for grid stability have been asleep at the wheel for a decade-plus.

What is solar export limiting, and why is it happening increasingly?

When not used in the home or business, solar power is exported to the grid. That electricity is then available to other nearby households to use. As solar generation overall is renewable energy, one would expect the more we export, the better for the grid from an environmental perspective. But this assumption is now being challenged as more solar systems are under export control. Export control, also known as solar export limiting, is something that is being brought in by a number of electricity networks across the country. This is where additional hardware or controls are installed to communicate with the solar inverter. The hardware or controls then have the ability to control the amount of electricity that can be sent back to the grid.

This commonly restricts the ability of an installed solar system to an export limit of 5 to 10kWh for the day but can vary in different circumstances and regions. Other limits that can be placed are the actual size of the solar system, so, for example, one would not be able to connect a larger solar system in certain regions with high solar penetration than, let’s say, 10 kW.

Some areas with a high proportion of solar systems installed in the area see a solar export limit of zero being set. This means the property or commercial business cannot export any solar electricity for a feed-in tariff (FiT) and can only rely on self-consumption.

hazard sign in regards to solar export limiting
Some substations had to be upgraded to cope with increased solar power entering the grid, as the grid originally was not designed for decentralised solar

The rules differ from region to region

You may find that if you want to install a solar system of higher capacity than 5 to 10kW, the network will require the system to be limited in the amount of electricity that can be exported at any point in time. If the solar system is producing more than 5kW of electricity that is not being used by the home, at any point in time, the additional electricity that is produced will effectively be throttled back, wasted and released as heat. Your local solar installer will be able to assist you in learning about your local solar export limiting rules.

For most homes and systems, the amount of electricity that will be lost and therefore not receive a FiT for solar exports will, however, have a small impact on the overall financial benefits and earnings from exported electricity.

Why is this solar export limit being implemented?

The electricity networks have had to introduce this system over a number of years for various reasons. The main one is due to the high volume of solar systems installed nationwide. In fact, Australia has the world’s highest solar system per roof ratio. Subsequently, this creates specific areas with a lot of solar electricity being sent back down the wires.

Unfortunately, the electricity retailers, generators and policymakers have been asleep at the wheel and have not either upgraded the grid or built enough battery storage capacity to absorb the solar in the peak generation time and release it when required.

Too much solar entering the grid at any point in time can harm the stability and strength of the grid if there is no demand for electricity at the same time. The surge in solar electricity into the grid creates voltage and frequency surges that can risk damaging transformers, network infrastructure, and household appliances and can cause blackouts.

In areas with an excess of solar, these restrictions may be imposed to control the amount of solar electricity being sent to the grid, maintaining the strength of the grid.

solar and the grid together
The solar export limiting rules are changing in some regions with grid congestion

Will I lose a lot of money?

Potential solar purchasers may worry they will lose some income from their solar system as their potentially exported electricity is not counted as a credit in their billing cycle. At the current feed-in tariff rate of 5 to 8 cents, the overall credit gained, other than for very large PV systems, is relatively small. Also, the solar export control policy forces solar owners to use their solar power within the house. This means they will install technology that pushes the electricity into their water tank to make hot water from the electricity or pre-cool and pre-heat the home with the excess solar electricity. So, the name of the game is to up one’s self-consumption.

Are there any benefits of solar export limiting

One of the benefits of having solar export limits imposed is that it may actually enable you to have a larger solar system installed. The reason for this is that when you have solar export limits in place, it does not matter whether or not you have additional generating capacity because it will not affect the grid. However, this additional capacity may enable you to self-consume more power in the home or business where you are a large electricity user.

Many people are also seeing the introduction of solar export limits to increase the value of adding batteries to their solar systems. If you have additional solar capacity that cannot be exported, the ability to store that electricity to use during the night rather than wasting it completely is increasingly more attractive.

The other benefit of solar export limiting is, as explained above that it reduces the chances of grid power surges and overall stress on the grid. When every household decides to export solar energy simultaneously, the grid’s power lines can become stressed. Reducing this stress also increases solar adoption overall, as installing a new residential solar system has little to no negative impacts.

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