Solar & Home Energy · 9 min read · Intermediate

DNO, G98, G99 & Export Limits: Solar Grid Connection Explained

Understand the role of the Distribution Network Operator, why G98/G99 thresholds matter and how an export-limiting scheme can affect solar and battery design.

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Key points & steps

  1. Your Distribution Network Operator (DNO) owns/operates the local electricity distribution network; it is different from the retail energy supplier that sends your electricity bill.
  2. Small generation and storage must be connected in accordance with the relevant UK engineering recommendations. MCS solar-PV requirements reference G98 for qualifying installations up to and including 16A per phase and G99 where the applicable generation exceeds that threshold.
  3. The threshold is based on AC generation capacity and can be affected by multiple generators connected at the same premises, including certain battery-storage arrangements, rather than simply the panel kWp printed on the quotation.
  4. G98 and G99 use different notification/application procedures. The installer should identify the correct route and handle the required DNO process for the proposed system.
  5. A DNO may agree a connection with a controlled export limit where the local network cannot accept the full potential export. Engineering Recommendation G100 covers export-limitation schemes used for this purpose.
  6. An export limit does not necessarily mean the solar array can never generate above that number: a suitable system can sometimes use energy in the home or battery while controlling only the amount that crosses the grid connection point.
  7. Batteries can affect the connection assessment because they may be capable of exporting as well as charging. Ask whether the quoted design counts battery and PV inverter outputs together and how export control is implemented.
  8. Keep the DNO approval/notification documents with the system handover pack because they describe the agreed grid-connection arrangement.

Practical tips

  • Do not confuse an export tariff with an export limit: one determines payment; the other is an electrical network connection condition.
  • Panel DC kWp, inverter AC rating and permitted grid export can all be different numbers in a legitimate design.
  • Final G98/G99/G100 classification is an installer/network matter; an online calculator should explain it, not issue grid-connection approval.

What you may need

  • Proposed inverter AC rating
  • PV and battery system design
  • DNO connection/approval correspondence
  • Installer/MCS handover pack

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