Last updated 5 November 2026 · BrightEdge Solar team
Short answer: Filling in a G99 application costs nothing to submit. The cost comes from the network operator’s assessment and design charge for preparing your connection offer. In Northern Powergrid’s area that starts at £990 + VAT for smaller low-voltage systems and is £1,290 + VAT for low-voltage systems over 50 kVA.[1] If the network needs work to take your export, you pay for any new cable or equipment that serves only your site, plus a share of upgrades at your connection voltage. The operator funds the rest.[1][5]
Most commercial solar and battery systems need a G99 application to the Distribution Network Operator (DNO) before they can connect. In Hull and East Yorkshire that’s Northern Powergrid. The paperwork itself is straightforward. The bill that comes with it is harder to pin down, because it depends on your system size, the voltage you connect at and whether the local network has spare capacity. This guide sets out the published fees, how network upgrade costs are split and what you can do to keep them down. For the step-by-step process, see our G99 application guide.
Key facts
- Small systems usually pay nothing. A single small-scale generator of up to 16 A per phase is connected under G98 and attracts no assessment and design charge.[1][3] See G98 or G99? to check which route applies.
- The charge is set in law and published. DNOs can recover the cost of preparing connection offers under the Electricity (Connection Offer Expenses) Regulations 2018. Each one publishes its fees in a charging statement.[4]
- Fees differ between DNOs. For a low-voltage system over 50 kVA, Northern Powergrid’s listed charge is £1,290 + VAT. SP Electricity North West’s is £8,300 + VAT.[1][3]
- You don’t pay for the whole network. Since April 2023, generation customers pay for upgrades at their connection voltage only, up to a cap of £200 per kW. Beyond that cap they pay in full.[5][6]
- Offers expire. A Northern Powergrid offer is valid for 90 days. An SP Electricity North West offer is valid for 180 calendar days.[1][3]
What you pay for in a G99 application
The G99 application costs come in two separate parts. The first is the fee for the DNO’s study and quote. The second is the connection charge for any physical work, and many systems don’t have one at all.
The assessment and design charge
The assessment and design charge pays for the DNO’s engineers to study your application, model the effect on the network and prepare a formal connection offer.[4] Northern Powergrid’s charge is fixed by category, so you know the figure in advance. You pay the same charge whether or not the final offer includes reinforcement.[1]
Northern Powergrid invoices the charge when the connection offer is issued. You pay it whether or not you accept the offer.[1] You get a 5 working day cooling-off period after you’re told the charge applies. If you cancel after that, you pay a share of the charge based on how far the work has got. If you accept the offer and then cancel, you get no refund.[1]
Optional budget estimates and feasibility studies
If you want a feel for costs before committing, you can ask for a budget estimate or a feasibility study. A budget estimate is a desktop indication of cost. Northern Powergrid lists it from £360 + VAT for low-voltage generation up to 50 kVA. A feasibility study looks at connection options in more detail. Northern Powergrid lists it from £540 + VAT, paid in advance.[1] Neither of these is a connection offer, so you’d still need a full application to connect.
Published fees: Northern Powergrid and SP Electricity North West
These are the listed assessment and design charges for generation in the two DNO areas we work in most often. Northern Powergrid publishes the same figures for its Yorkshire and Northeast networks.[1][2]
| Generation connection | Northern Powergrid (Yorkshire and Northeast) | SP Electricity North West |
|---|---|---|
| Single small-scale generator (G98, up to 16 A per phase) | Zero | £0 |
| Other generation up to 20 kVA, LV | £990 | £2,380 |
| Over 20 kVA up to 50 kVA, LV | £990 | £3,170 |
| Over 50 kVA, LV | £1,290 | £8,300 |
| Up to 250 kVA, HV | £1,930 | £9,090 |
| Over 250 kVA up to 1 MVA, HV | £2,640 | £10,270 |
| Over 1 MVA, HV | £5,050 | £13,170 |
| When it’s payable | When the offer is issued | Mostly when you accept the offer* |
All figures exclude VAT and come from each DNO’s statement effective June 2026.[1][2][3] Northern Powergrid’s figures are minimum charges, and it can charge more for extra work or where a transmission impact assessment is needed.[1] The voltage band is the highest voltage of the assets needed, including any reinforcement, so a site that connects at LV can fall into an HV band. *SP Electricity North West charges low-voltage and HV-up-to-1-MVA applications on acceptance. Over 1 MVA, £2,500 is due when the offer is issued and the rest on acceptance.[3] Other DNOs publish their own figures, so always check the statement for your area.
Who pays for network upgrades?
If the network can take your system as it is, the assessment and design charge may be the only DNO cost. If it can’t, the connection offer will set out the work needed and a connection charge. That charge is set by the Common Connection Charging Methodology, which all DNOs follow.[1][5]
Extension assets: paid in full by you
Extension assets are the new cables, switchgear or transformers that serve only your connection. You pay for these in full.[1]
Reinforcement: shared, with a cap
Reinforcement is work to strengthen the shared network, such as a larger transformer at the local substation. Ofgem’s Access reforms changed how this is charged from 1 April 2023.[5][6] For generation:
- You pay a share of reinforcement at the voltage of your point of connection. The share is worked out with cost apportionment factors, which compare the capacity you need with the capacity being added.[1]
- The DNO pays for reinforcement at higher voltages than your point of connection.[1]
- A high-cost project threshold of £200 per kW applies. Reinforcement costs above the threshold, at your connection voltage and one voltage level above, are charged to you in full.[1][6]
For a 200 kW system, for example, the threshold works out at 200 × £200 = £40,000. Reinforcement costs above that figure would fall to you in full rather than being shared. Most commercial rooftop systems never get near this level, but it’s why a small number of offers come back with large figures.
Contestable work and independent connection providers
Some connection work is “contestable”, which means an accredited independent connection provider (ICP) can do it instead of the DNO. The DNO still does the non-contestable work, such as the final connection to its live network, and charges for approving and inspecting the ICP’s design and work.[1] On larger jobs it’s worth getting an ICP quote alongside the DNO’s.
Larger projects and the transmission network
For bigger systems, National Grid may need to check the impact on the transmission network. In England and Wales the threshold for that check was raised from 1 MW to 5 MW in May 2025. It stays at 1 MW at some constrained grid supply points.[7] Where a transmission check is needed, its fees aren’t included in the DNO’s listed charges and may be passed on.[1]
How to keep G99 costs down
- Size to the network. If you already know the local network is tight, sizing the system to fit can avoid reinforcement altogether.
- Use export limitation. A G100 export limitation scheme caps what you send to the grid. That can let a larger system connect without upgrade work.
- Add a battery. A battery stores surplus solar for later use on site instead of exporting it. That works well alongside an export limit.
- Reuse an existing approval. If your site already has G99 approval, a new system or a replacement inverter may be designed to fit within it.
- Apply once, with the right details. The assessment and design charge applies to each connection offer. A complete, accurate application avoids paying twice for a revised offer.
- Watch the deadline. If you need time to arrange funding, plan around the offer validity period so the offer doesn’t expire before you accept it.
In practice: how we handle G99 costs
We handle the G99 application as part of every commercial project. Any DNO costs are shown separately in your quote, so you can see exactly what the network operator is charging. On our industrial estate project in Peterborough, we ran three Type B G99 applications with UK Power Networks and met its engineer on site for witness testing. At an 86 kWp rooftop system in Doncaster, we sized the new SolarEdge inverter to fit within the site’s existing G99 approval, and a SolarEdge ONE Commercial Controller handles export limitation. At an industrial estate in Oldham, each of the seven units has its own G99 connection, so each one is a separate application.
Timing matters as much as cost. G99 typically adds 8–12 weeks to a project, and our G99 timeline guide explains where that time goes. Under Ofgem’s guaranteed standards, a DNO that misses the deadline for a low-voltage generation quote (45 working days) pays £85 for each working day it’s late. The HV deadline is 65 working days and the payment is £180 a day.[8]
When this doesn’t apply
These charges are for connecting to the public distribution network in Great Britain. If your system is small enough for G98, you notify the DNO within 28 days of commissioning and there’s no assessment and design charge.[1] If you’re adding solar on a private network, such as a site that takes its supply through a landlord’s network, the arrangements may differ. Large ground-mounted schemes at EHV or 132 kV have much higher charges and longer timescales. For those, start with a budget estimate and a feasibility study.
Frequently asked questions
How much does a G99 application cost?
In Northern Powergrid’s area, the listed assessment and design charge for generation is £990 + VAT up to 50 kVA at low voltage, £1,290 + VAT above 50 kVA at low voltage, and £1,930 to £5,050 + VAT at HV, as minimum charges. Other DNOs charge different amounts, so check the charging statement for your area.
Is the G99 fee refundable if I don’t go ahead?
Usually not. Northern Powergrid’s charge is payable once the offer is issued, whether or not you accept it, and it isn’t refunded if you accept and then cancel. You can withdraw without charge within 5 working days of being told the fee applies.
Who pays if the network needs upgrading?
You pay in full for new assets that serve only your site and a share of reinforcement at your connection voltage. The DNO funds reinforcement at higher voltages. Costs above £200 per kW at your voltage and one level above are charged to you in full.
Does a G98 system have a fee?
No. A single small-scale generator of up to 16 A per phase, connected under G98, has no assessment and design charge with Northern Powergrid or SP Electricity North West. You notify the DNO within 28 days of commissioning.
Can export limitation reduce G99 costs?
Often, yes. If the network can’t take your full export, a G100 export limitation scheme can cap what you send to the grid. That can let you connect without reinforcement work, but some generation may be curtailed unless a battery or extra daytime use soaks it up.
How long is a G99 connection offer valid?
Northern Powergrid offers are valid for 90 days, and SP Electricity North West offers for 180 calendar days. If an offer expires, you may need to reapply and pay again, so it’s worth arranging funding before the offer arrives.
Planning commercial solar? We’ll handle the G99 application
We’ll check your site, size the system to suit the local network and handle the G99 application, with any DNO charges shown separately in your quote. We install commercial solar and batteries across Hull, East Yorkshire, Yorkshire and the North of England, with a 24-month warranty on commercial installs.
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Sources
- Northern Powergrid (Yorkshire), Statement of Methodology and Charges for Connection, June 2026: https://www.northernpowergrid.com/sites/default/files/assets/Northern%20Powergrid%20%28Yorkshire%29%20Connection%20Charging%20Methodology%20Statement%20June%2026.pdf (checked 5 Nov 2026)
- Northern Powergrid (Northeast), Statement of Methodology and Charges for Connection, June 2026: https://www.northernpowergrid.com/sites/default/files/assets/Northern%20Powergrid%20%28Northeast%29%20Connection%20Charging%20Methodology%20Statement%20June%2026.pdf (checked 5 Nov 2026)
- SP Electricity North West, Statement of Methodology and Charges for Connection, effective 1 June 2026 (v5.9): https://www.enwl.co.uk/globalassets/get-connected/apply-for-a-new-connection/common-charging-methodology/statement-of-methodology-and-connection-charges-1-june-2026-v5.9.pdf (checked 5 Nov 2026)
- legislation.gov.uk, The Electricity (Connection Offer Expenses) Regulations 2018: https://www.legislation.gov.uk/uksi/2018/254/contents/made (checked 5 Nov 2026)
- Ofgem, Access and Forward-looking Charges Significant Code Review: Final Decision, May 2022: https://www.ofgem.gov.uk/sites/default/files/2022-05/Access%20SCR%20-%20Final%20Decision.pdf (checked 5 Nov 2026)
- Ofgem, Decision on DCP406 (Access SCR changes to the Common Connection Charging Methodology): https://www.ofgem.gov.uk/publications/decision-dcp406-access-scr-changes-cccm (checked 5 Nov 2026)
- NESO, Streamlining the connection of distributed generation projects (CMP446): https://www.neso.energy/streamlining-connection-distributed-generation-projects (checked 5 Nov 2026)
- Ofgem, Guaranteed Standards of Performance payment update 2026: https://www.ofgem.gov.uk/sites/default/files/2026-03/Guaranteed%20Standards%20of%20Performance%20payment%20update%202026.pdf (checked 5 Nov 2026)
