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G98 or G99! Whats all the fuss about?

Whats the difference between G98 & G99 installation routes?

Solar Pv G98 or G99 Applications

As renewable energy installers we have to comply with various regulations when we install a Solar Pv system. Your new Solar Pv system which generates power for use in your own home also has the ability to export power to the gird to be used elsewhere on the network. Having the ability to produce and also consume, you are now known as a prosumer with a small scale generation site.

These electrical networks are managed by DNOs (District Network Operators) meaning we have to comply when connecting to their network. One of the biggest concerns for the DNO is to protect their own infrastructure such as cables & transformers etc. The way they do this is by enforcing two installation routes, G98 or G99 regulations.

To ensure that their network is safe and protected the DNO set very simple and straight forward guidance on the size of systems we can install. Under G98 regulations, we are allowed to install 16Amps per phase, meaning that on a single phase installation such as domestic homes, we can install a generator / inverter up to and including 3.68kw without permission.

It is not just the inverter size that can determine whether or not a G99 application is required, but also the battery. AC coupled batteries such as the Tesla power wall are classed as "Generator" and therefore need to be included on a G99 application. Even in the event of your inverter being less than 3.68kw if you match this with an AC coupled inverter you will be required to submit a G99 application.

G98 Regulations Installations

- Under G98 regulations we can post notify the DNO after the installation as long as the generator / inverter is no bigger than 3.68kw.

- Most inverters can have oversized DC input meaning that on a 3.68kw inverter you can install up to 7kw of Solar Pv array.

- Post notification so no application or pre install works are needed.

- This is the fastest route to installation.

- 3.68kw for Single phase installations

- 11.04kw for Three phase installations

G99 Regulations Installations

- G99 regulations for generator / inverter installations greater than 16Amps per phase such as 6kw, 8kw, 10kw single phase or 12kw upwards on Three phase.

- Full G99 applications are required prior to any works being carried out. The DNO will then carry out network assessments and in some cases will carry out works on the network to accommodate your installation.

- The DNO in almost all cases, will quote you a cost for you to accept. The cost of this can vary depending on the condition of the local network and how much work they need to do.

- G99 applications installations allows you to produce more power to be consumed by the property and help to reduce the overall dependancy from the electricity suppliers which helps to save you more money against your electricity bill.

- Minimum 45 working day wait from submission of an application and theres no guarantee of the application being granted.

G100 Regulations Installations

- In some cases following a G99 application, where the local DNO network can't support the full system size applied for, the DNO will ask us to re-submit using a G100.

- Where an inverter has the capability to export greater than 16amps per phase, and where the network cannot take this addition export load, the DNO will ask us to limit the export to a required limit.

- This means that they will allow you to install the full applied for inverter generator size to use around the property but limit the amount that can be exported to protect their network.

If you have any questions regarding G98 or G99 please get in touch.

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