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Technical Aspects – Connecting to the grid

Connecting to the grid has always been the main show stopper with large-scale connections as most network providers simply cannot take anymore excess solar onto their network as the variations in solar production are causing all sorts of problems with local electrical infrastructure. As solar produces low voltage power it cannot interface on a level above the local network so when an excess power is being pushed to the grid it causes the voltage at the transformer to increase. Voltages have been seen as high as 265v when it should only be 240-250v. This is causing problems with power for all consumers on the electrical network as electrical appliances are designed to use 240v and the excessive voltage is causing power trips and appliances to fail.

To counteract this, in areas with a high amount of solar penetration on the network they have reduced the standing voltage on the transformer from 240v to 230v for example which will allow the solar to feed back in and not cause the voltage to exceed acceptable levels. Unfortunately, this is not a long term solution to the problem as reducing the voltage of the transformer to allow for solar during the day will mean that in cloud cover or at night time when there is no solar on the network the voltage is too low and the same problems occur. This is still an on-going battle for power companies and will eventually lead to the installation of large-scale battery systems that will be able to capture excess energy during the day and ‘dump’ it back onto the network in times where the voltage is too low.

The responsibilities of being a network owner and operator such as Essential Energy, Energex or Ergon require them to supply quality and safe power to consumers and excessive solar penetration can cause them to fail to meet these responsibilities.

A point has even come where retailers are refusing to pay a ‘Feed In Tariff’ for excess power put back into the grid and are starting to enforce the installation of sophisticated electrical equipment that can effectively prohibit any power leaking back onto the network. This equipment works in the form of an advanced relay system.

These relay systems can start with a very simple design and can become very sophisticated. They are designed to ‘kick in’ when solar production exceeds demand at the property and in doing so will effectively shut off the solar instantly to stop any power possibly feeding back into the grid. The more simple designs simply act as an on-off switch which is not good for the power network or the appliances at the property due to the flood-gate (water hammer) type effect you have with electricity when a high demand is turned on or off immediately.

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More sophisticated systems like those used by Gem Energy and recently installed on businesses like Bundaberg Palms, Austchilli and Gin Gin & Dry effectively ‘ramp’ the solar system up and down to meet the demands of the building. These systems are more expensive but certainly worth the extra cost. Gem Energy are able to ramp our systems in 1% increments whilst most competitors are only able to ramp at 20% commonly or 6% increments at the best of times. This allows for our systems to be producing more power when others are limited.

When commencing a solar installation Gem Energy will prepare electrical diagrams drafted by our electrical engineer providing full visibility on our sophisticated electrical grid protection equipment which will be submitted to the power company to get 100% approval on the solar connection to the network.