DNO connections for UK commercial solar
How to ask about G98, G99 and G100, export limits, applications and commissioning without treating a route as a guarantee.
Reviewed 2026-09-24 · 6 min read
The network operator matters
A solar project connects through the local Distribution Network Operator. The process depends on connection characteristics, generation, export and network conditions. Identify the operator and who owns application, engineering response and costs.
G98 and G99 are commonly discussed generation connection routes, while G100 relates to export limitation. The correct route is technical and regulatory; do not select one only because it sounds quicker.
Establish the site’s existing import capacity, point of connection, phases, transformers and private network arrangements. A large rooftop can still face a constrained connection, while onsite demand and an export-limiting controller may change the options. The DNO’s response, not a generic system size threshold, determines what can proceed.
Ask whether the design includes generation on more than one building or meter. Landlord supplies, tenant supplies and private-wire arrangements can create separate responsibilities for protection, metering and settlement. Put those boundaries in the scope of work.
Ask for assumptions
Request maximum import/export, phases, inverter settings, protection, metering and export control. Confirm whether the design assumes zero, capped or unrestricted export and what happens if the controller fails. Identify reinforcement, studies, witness testing and remedial works.
Keep the DNO offer and conditions. Acceptance is not the same as planning, building, landlord consent or completed installation.
An application may require technical information, protection settings, drawings and evidence from the equipment manufacturer. Agree who prepares each item and who pays if the DNO asks for additional studies. Confirm the expiry date and any conditions that must be met before energisation.
Export limitation deserves particular scrutiny. Ask whether it is fail-safe, independently monitored and tested at commissioning. If the business later adds storage, EV charging or another generation source, establish whether the original connection agreement and control scheme remain valid.
Commissioning and change
Establish who tests protection and submits commissioning documents. Changing inverter, capacity or export controls can alter the connection position; require approval before substitutions. Multi-building sites need particular care around private networks, multiple meters and expansion.
Set a hold point before energisation so the owner can confirm that the installed equipment matches the accepted design. Request protection test results, settings, single-line diagrams, meter details and the final notification or approval. Store them with the asset records so a future operator is not forced to reconstruct the connection history.
When a project is phased, document what is live, what is reserved and what would trigger a new application. A later extension should not silently exceed the accepted limits.
Ask how the connection will be monitored after handover and who responds to a protection trip or export-control alarm. The owner should know the normal operating limits and have a clear escalation route rather than discovering the process during an outage.
Common questions
What is G99?
It is associated with generation connections under relevant distribution-network technical requirements; the DNO or designer confirms the process.
Does G100 remove DNO work?
No. Export limitation still needs suitable design, evidence and DNO engagement.
Who pays reinforcement?
The connection offer and rules determine the position. Request a written cost breakdown.