The G98 and G99 certificates are required applications related to integrated microgeneration and storage units that allow solar PV systems to be connected to a grid network. In other words, they are to be taken into account during a PV installation process. For this reason, in the following article, we have included all the necessary information about these certificates

G98 and G99 certificates: what are they?

These certificates confirm that your solar PV system has met the requirements for the connection of generation equipment in parallel with the national grid. They contain a list of requirements to connect solar PV systems (as well as other microgenerators)  to public low voltage networks so they work in sync. It is a requirement for every solar PV system to have certification. Once your solar PV system is installed, the final prerequisite to completing your installation is obtaining one of these certificates which grants approval to connect to the national grid. 

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Are they mandatory?

Yes, it is mandatory to obtain a G98/G99 certificate. The consequences of not having them are serious: your system could be permanently cut off from the grid.

Who is responsible for filling out the certificates?

Your solar PV installer has the responsibility  to fill out these certificates. At Otovo, we take care of the completion of the applications as well as chasing your DNO to try to get approvals back as quickly as possible. Once we hear back from the DNO or we receive approval we let you know. G98 sized projects register paperwork post installation whereas G99 size projects require pre-approval from your grid operator. 

What's the difference between G98 and G99 certificates?

The G98 certificate

This certificate applies to systems with an installed inverter with potential output of up to 3.68 kW / under 16A per phase. It is important your system is registered with  the National Grid for a G98 within 28 days of commissioning the installation of your PV system. Many grid operators provide confirmation of registration within a business day however some take up to 30 working days to provide this confirmation. Your solar PV installer has the responsibility of filing this paper and should send this to you once received as you will need it to apply for the Smart Export Guarantee.  

When you install your solar PV system with Otovo, we will fill out the G98 application upon completion of your installation, and let you know once it's automatically approved.

The G99 application

A G99 Certificate is for systems with one or more inverters installed with a total potential output above 3.68 kW / above 16A per phase. In other words, energy generation installations with export potential above 16A and or 3.68kw per phase must comply with Engineering Regulation (EREC). This form is downloaded from the National Grid official website by your installer and sent to your regional office. 

If you choose our services, Otovo completes this certificate before the installation takes place, as required. It can take 35-45 working days to receive notification of the application's approval or rejection from some grid operators though many have a much lower average response time. Otovo have worked with all the major distribution network operators (DNOs) as well as independent distribution network operators so have a comprehensive knowledge of specificities of each as well as average response times across different grid operators. 

Why does it take so long to receive this approval?

Many grid operators have developed a streamlined online system to approve G99 applications quickly, including the largest grid operator in the country, UK Power Networks which results in a speedy approval process. However some grid operators have more manual application processes as well as greater inefficiencies in applying or interpreting some guidelines from Energy Networks Association (ENA). In addition a very small minority of projects (3% or lower) fall under unique situations with their grid operator such as a shared management structure or at or near capacity distribution nodes.   

A G99 application can require a variety of documentation including

  • location plans
  • connection designs
  • site layout plans
  • manufacturer's specifications, etc.

Therefore if a grid operator requests documentation beyond the scope of a normal project it can take additional time to prepare this supplementary documentation as well as the time to go back and forth with the grid operator.  

That said, the vast majority of Otovo projects receive DNO approval within 10-20 working days. However it is prudent in setting expectations that it can take up to 45 working days from when the grid operator determines an application is complete to receive approval to install. 

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G98 and G99 certificates are a part of the process of installing solar panels and harnessing solar energy. They are mandatory which is why it is really important to check out with your solar installation provider the details in order to avoid unpleasant surprises. 

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