G99 Grid Connection for Brewery Solar, Explained

Before a single panel goes on your brewhouse roof, one piece of paperwork decides whether the project runs to schedule or stalls for months: the grid connection. For breweries this almost always means a G99 application to your Distribution Network Operator (DNO), and getting it wrong, or starting it late, is one of the most common reasons a solar install slips a quarter.

This guide explains the connection process in plain terms: why a brewery is nearly always a G99 job rather than the simpler G98, what the 45-working-day DNO clock actually covers, how G100 export limitation works in your favour, and how to identify the regional operator you’ll be dealing with. Solar tackles the roughly one-third of your energy that is electrical, the pumps, the packaging line, compressed air and above all the 24/7 glycol chilling, not the thermal load of the boil. But it’s that electrical demand that sets your array size, and your array size that sets which connection route you’re on.

Why a brewery is almost always a G99 connection

The rules that govern how you connect on-site generation to the grid are Engineering Recommendations written by the Energy Networks Association. There are two you need to know:

• G98, the “connect and notify” route for small, type-tested micro-generators. You can install first and tell the DNO afterwards.
• G99, the “apply before you connect” route for everything larger. You submit an application, receive a formal Connection Offer, accept it, and only then energise the system.

The line between them is drawn per phase, not by total kilowatts, which trips people up.

The 16A-per-phase line between G98 and G99

G98 applies up to and including 16 amps per phase. Breweries run on a three-phase 400/415V supply, you need it for the refrigeration compressors, the packaging line motors and the compressed-air plant. On three phases, 16A per phase works out to roughly 11 kW of generation as the G98 ceiling.

Now look at typical brewery array sizes. A nanobrewery starts around 6–30 kW, a craft micro sits at 20–50 kW, a growing craft site at 50–200 kW, and a regional independent at 250–750 kW. Only the very smallest nano array squeaks under the G98 threshold, and even then, only just. In practice, a brewery solar system is a G99 connection. Plan for it from day one rather than discovering it after you’ve costed the panels.

What the G99 application actually involves

A G99 application is more than a form. Your installer (acting as your agent) submits:

• A completed application to the DNO with the proposed generation capacity and the export capacity you’re requesting.
• A single-line diagram of the electrical installation.
• The inverter specifications and protection settings, G99 sets the rules for how the system disconnects itself if the grid goes down, so the network stays safe for engineers working on it.
• For larger systems, a commitment to witness testing or commissioning, where the DNO (or an approved party) verifies the protection actually trips as declared.

The DNO responds with a Connection Offer. This may be a straightforward acceptance, or it may come with conditions, and occasionally with a bill for network reinforcement if your local infrastructure can’t absorb the extra export without upgrades. That reinforcement charge is the single biggest cost risk in the whole exercise, and it’s exactly the risk G100 (below) is designed to remove.

DNO timelines: the 45-working-day clock

For a generation connection up to and including 1 MW, the DNO is required to make a connection offer within 45 working days of a valid application. That’s around nine calendar weeks before you even have terms to accept, and it sits entirely outside the installation programme.

Sequence it properly and the connection application runs in parallel with your structural survey, MCS design and finance approval. Leave it to the end and it becomes the bottleneck that holds up commissioning. The order that keeps a project on track is: agree the system design, submit the G99 application early, and let the 45-day clock run while everything else proceeds. When you’re modelling payback, treat the connection period as fixed lead time, our cost breakdown and savings calculator assume the array is generating, not sitting finished and waiting for an energisation date.

Know your DNO: the regional operators

Your DNO is set by geography, not by who supplies your electricity. Six operators cover Great Britain. You can confirm yours from the first two digits of your MPAN (the supply number on your electricity bill) or via the Energy Networks Association’s operator lookup.

Region	Distribution Network Operator
London, East of England, South East	UK Power Networks
West Midlands, East Midlands, South West England, South Wales	National Grid Electricity Distribution
North East England, Yorkshire	Northern Powergrid
North West England (incl. Greater Manchester)	Electricity North West
Merseyside, Cheshire, North Wales	SP Energy Networks
Southern England, North of Scotland	SSEN

A Manchester or Salford brewery applies to Electricity North West; a Birmingham or Bristol site to National Grid Electricity Distribution; a London or Kent brewery to UK Power Networks. Knowing this up front matters because each operator has its own application portal, its own queue, and its own recent history of local reinforcement, which can shape both the timeline and whether G100 becomes worth doing.

G100 export limitation: a brewery’s shortcut

Here’s where a brewery’s electrical profile becomes a genuine advantage. Because glycol chilling runs continuously through fermentation and the packaging line and compressed-air plant run through the day, breweries self-consume 75–90% of everything a rooftop array generates. Very little is ever exported.

G100 is the Engineering Recommendation that lets you fit a certified export limitation device, capping how much power you push to the grid at an agreed figure, sometimes to a low value, sometimes to zero export. Why does that help?

• It can unlock a larger array. If the DNO’s constraint is how much your site can export, limiting export lets you install a system sized to your daytime demand without triggering the reinforcement that a full-export connection of the same size would.
• It can avoid or reduce reinforcement costs. A zero- or low-export connection asks far less of the local network, so it’s more likely to be offered without a reinforcement charge attached.
• It can shorten the route to approval, because the DNO is being asked to accommodate very little additional flow onto their network.

The catch to be honest about: the limitation scheme itself must be type-tested and agreed with the DNO, and it caps your export earnings. But for a high-self-consumption brewery, exported units earn only the Smart Export Guarantee rate, a supplier-set figure currently in the region of 12–16p/kWh, whereas every self-consumed unit offsets grid import at roughly 25p/kWh. Giving up a little export to secure a bigger, faster, cheaper-to-connect array is usually the right trade. It’s precisely because a brewery uses most of its own generation that G100 tends to pay off here more than in other sectors.

How grid connection shapes your system size

The temptation is to size the array to your roof. The better approach is to size it to your electrical demand and your connection terms together. A regional brewery generating around 850 kWh per kWp each year, self-consuming most of it, and limiting export under G100 will typically land on a larger, better-returning system than one designed around a full-export G99 offer that attracts a reinforcement bill.

This is a decision to make with your installer before the G99 application goes in, because the export figure you request shapes the offer you get back. If you’re still weighing whether the numbers stack up for your site, start with is solar worth it for a brewery, then look at what funding and capital allowances apply on the grants and funding page. Larger regional and independent breweries, where connection and reinforcement questions bite hardest, are covered in more depth on our regional brewery solar page.

Common questions

Does my brewery need a G99 application or can I use G98?

Almost certainly G99. G98 only covers generation up to 16 amps per phase, about 11 kW on a three-phase supply. Brewery arrays start around 20–50 kW for a craft micro and climb from there, so all but the smallest nano systems cross the threshold and require a full G99 application before you can connect.

How long does DNO approval take?

For a connection up to 1 MW, the DNO must issue a Connection Offer within 45 working days of a valid application, roughly nine calendar weeks. Submit it early so it runs alongside your survey, design and finance rather than becoming the thing that delays energisation.

Will I have to pay for grid reinforcement?

Sometimes. If your local network can’t absorb the extra export, the Connection Offer may include a reinforcement charge, which is the biggest cost variable in the process. Because breweries self-consume most of their generation, a G100 export-limited connection often avoids this entirely by asking very little of the grid.

What is G100 and should a brewery use it?

G100 lets you fit a certified device that caps export to an agreed limit, including zero. For a brewery self-consuming 75–90% of its output, exported units earn only 12–16p/kWh anyway, so limiting export to secure a larger, faster, cheaper-to-connect system is usually the better commercial call. Confirm the specifics with your installer and DNO.

Get the connection sequenced right

The grid connection is boring paperwork that quietly governs your entire timeline. Sequence the G99 application early, request an export figure that matches how much you actually self-consume, and use G100 where it unlocks a bigger array without a reinforcement bill. For the rules themselves, the regulator Ofgem publishes guidance on connecting to the network, and the Energy Networks Association hosts the operator lookup and the G98/G99/G100 Engineering Recommendations.

When you’re ready to get a system designed around your real electrical demand and connection terms, request a quote and we’ll factor the DNO route into the plan from the start.