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What Is a Grid-Tie System?

Written by Madelein Kroukamp

It is a misconception to think that once you use solar panels to generate your own electricity, that you are now “off the grid”. In reality, what most homeowners adopting renewable energy are doing is installing a “grid-tied solar system”. It sounds counterintuitive to go solar but still be connected to the municipality’s power lines. To understand this, you will have to understand what exactly a grid-tied solar system is and how it works.

THE COMPONENTS INVOLVED

A grid-tied solar system needs only four components to function. These are solar panels, a grid-tied inverter, an electricity meter, and a power grid. Thinking that it would be easy to take on the installation because there are only a few components would be a mistake, though. It is highly recommended to consult with a system engineer and installer to do a custom-designed system to fit the needs required.  

WHERE DO THE BATTERIES GO?

Solar energy is created, in layman’s terms, when the sun hits the solar panels and creates direct current (DC) electricity. We use alternating current (AC) in our homes, so an inverter is needed to switch the DC into AC.

When more electricity is generated than used, that extra energy needs to be stored somewhere. This is where the batteries usually come in. But not so with a grid-tied system. When connected to the municipality’s power lines, the extra power produced feeds back into the power grid and stored there, not in batteries.

This is only possible while the sun is shining. During the evening, and when there isn’t sunlight, the energy required is then pulled from the grid. So, there is no need for batteries to store extra energy for later use. Electricity will always follow the shortest route, meaning that the electricity is first used in the home, and then moves into the power grid.

When the energy that is being fed back into the system is equal to the energy that is consumed, your utility bill will be at zero. In countries such as America, you get paid for the extra energy that your system feeds into the grid, meaning that you can actually make money with your solar system. This system has been put into place in certain regions of South Africa and legislation is pushing for it to be adopted country-wide.

What should I know about grid-tied systems?

Batteries are very costly. Trying to save money AND be “off the grid”, is not feasible. Initial costing fees for using a grid-tied system is significantly lower than using an off-grid system. A grid-tied system does not require any extra equipment and there is little to no maintenance required. They are not prone to failure, keeping the costs low.

Sunlight availability, weather, and seasonal changes play a role in the amount of electricity generated. It thus varies the import and export of electricity. During the summer there is ample sunlight and usually a surplus of energy flowing into the grid. In winter, with less sunlight, more power will be imported and restores the balance. In spring and autumn, imports and exports are normally in balance.

Using the grid as storage for extra electricity means that when the grid doesn’t have any power like during loadshedding, the home will subsequently also not have access to power. If having power during loadshedding is a necessity for you, you need to speak to a specialist as to how to achieve this.

Thank you for reading this article. If you feel we have left out any important information or would like to contribute to this site and content, please get in touch with us by leaving a comment or emailing us.

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