DNO

Distribution Network Operator

Potential solar customers often ask, why is there a delay in fitting my solar panels due to the certification that is mentioned by SolarTherm UK, when other companies can fit straight away? One of these reasons is the DNO permission your solar panel installation requires when being connected to the grid. Some other companies do not apply for DNO permission, leaving you open to penalties, and the removal or inability to apply for export tariff payments.

Why do I need to be connected to the grid?

A SEG tariff will pay you a fixed rate sum for any exported electricity to the grid power network. Of course, adding a battery storage system and/or a hot water immersion device can use up much of the electricity that ordinarily would be exported, but dependent on system size, time of year and your homes consumption, you may still export energy back to the grid. With any solar installations installed over 3.68kW (16A per phase), there is a requirement to submit a G99 Application regardless, this is even if a larger inverter is installed and then restricted via a G100 device. If for example an installer uses a 5kW Inverter but restricts this to 3.68kW using a G100 device, this still requires a G99 application – it does not matter what the inverter is restricted to. The DNO is not just looking at what it can accept from an export point of view; when you apply they will carry out a Network Study. This will also look at things like the voltage rise on the network and if adding the new electricity generation causes this to fall outside of their tolerances.

Who are the DNO?

The Distribution Network Operator. This is not just one corporate set-up, it is six different companies that cover the UK’s grid. Check the map to see which DNO covers your area.

How long does it take?

One of the most frequent questions we hear in the offices from our customers at SolarTherm UK is, how long does it take?

In 2010 when we were first trading, we sent off notification on a simple form and the permission process was swift. However, as Solar PV has become more mainstream the applications process has become slightly more complex and in some cases expensive, as certain applications are now having to be paid for, but more importantly permissions from some DNO applications are taking up to 70 days.

This contrasts with certain DNO’s stipulating that it takes a mere 10 days. Our office can evidence that on average and at the time of writing a G99 application is being returned around day 30/35.

Your SEG (Smart Export Guarantee) Tariff

Utilities such as Octopus Energy now require a confirmation letter from the DNO confirming that the Solar PV system has been notified. This was never the case historically and the real frustration for us here at SolarTherm UK and of course our customers is whilst you are awaiting your SMETS2 meter and your MCS certificate you now must send off your G99 approval, meanwhile you are NOT getting paid the export tariff.

There is nothing worse for you or us knowing you are exporting surplus electricity for free and there is not much either party can do but wait and chase the documents. Of course, if your system is adequately sized, you have a battery or hot water immersion device, and it’s not peak summer then the chances are you are not losing a fortune. But still it’s your power and in our opinion this rule was added as it is of course very profitable for a utility provider to take 4/6 weeks of export from thousands of PV systems across the UK.

Rest assured SolarTherm UK chase the DNO applications daily on your behalf.

If you require any more information on these matters, please feel free to email [email protected]