At 50 kW three-phase the paperwork changes character. The simplified forms end and the Standard Application Form, the SAF, begins. The operator stops checking a register entry and starts studying its network. The answer is no longer a yes; it is an offer, with works in it and often a bill.
This is part 4 of DNO applications by size. It covers the commercial roof and the small field: 50 kW up to, but not including, 1 MW. Everything here is still G99 Type A. What changes is the form, the wait and the money.
Why the form changes at 50 kW
G99 says a job with an aggregate capacity above 50 kW three-phase applies on the Standard Application Form, generally available from the operator's website. Every GB operator uses the ENA's SAF. Versions differ slightly in the wild, so download the operator's current copy.
Two other things change at the same line.
The fully type tested shortcut ends. Under 50 kW a register entry stands in for most of the technical assessment. Above it the operator assesses the installation: harmonics under EREC G5, voltage step and flicker under EREC P28, fault contribution, and the protection at the connection point. The inverter's type-test evidence still helps; it is no longer the whole answer.
MCS stops. MIS 3002 covers solar PV up to a maximum DC output of 50 kWp on a building. Above that there is no MCS certificate for the installation. The DNO record and the electrical certification become the compliance trail.
What the SAF asks for
The SAF runs to more than fifty pages. A Type A job completes Parts 1, 1a, 2 and 3. Parts 4 and 5 are for Type B and above, and stay empty.
Part 1, the applicant and the site.
- The applicant, which is the customer: company name, registered number, address, contact.
- The consultant or agent, which is you.
- The site: name, postal address, and a site plan with the boundary drawn in red.
- The technology, and any existing connection agreements.
- The import MPAN, and the export MPAN if one exists.
- The connection point, as an OS grid reference or a description, and the preferred connection voltage.
- Whether the site is new or existing, and whether you want the contestable works quoted.
- Whether you want a budget estimate or a formal quote.
Part 1a, the attachments. The single line diagram, the site plan, and any studies or manufacturer's evidence you already hold.
Part 2, the connection.
- Firm and non-firm import and export in kW and kVAr.
- Whether you would accept a constrained connection, where the operator can curtail export.
- The security level: a single circuit is the default.
- The site's maximum fault current contribution.
- The interface arrangements: how the generation connects, disconnects and synchronises, with a diagram. The form says an application without this is delayed.
Part 3, the generating units. For each unit: the identifier, the type-test references, whether it can run islanded, whether there is on-site load, the unit class, and the electrical data. Solar inverters are series-inverter-connected units; batteries are electricity storage.
Most of Part 1 and Part 3 is in a finished design already. The parts that need a human are the earthing, the interface protection detail, the preferred date, the quote type and the signature.
Budget estimate or formal quote
The SAF asks which you want, and it matters.
A budget estimate is an indicative figure. It is quick, usually free, and not an offer you can accept. Use it to test whether a site is worth designing before you spend on the survey and the drawings.
A formal quote is the connection offer. It names the point of connection, the works, the cost and the terms. Several operators charge an assessment and design fee to produce one for larger schemes. When it is charged, and whether it is refundable, differs by operator: some take it with the offer whether or not you accept, others only at acceptance. Check the operator's charging statement before you tick the box.
The clock and the offer
The wait is not the 10 working days of the small lanes. Ofgem's guaranteed standards give the operator a set number of working days to quote, depending on the voltage and the scale of the works. For a full generation application expect a clock in the tens of working days, commonly in the 45 to 65 range, and read the operator's own page for its figure. The clock pauses whenever the operator is waiting on you.
The offer arrives as a letter with a validity period. G99's own forms note that connection offers are valid for three months. To hold the capacity you accept within the period and pay whatever the offer requires. Miss the date and you apply again from the back of the queue.
Read the offer for three things.
- Works. Reinforcement the operator will do, and what it costs. The customer pays a share under the connection charging rules.
- Constraints. A constrained or flexible connection that lets the operator curtail export at times, in exchange for a quicker or cheaper connection.
- Export limits. An offer may permit less export than you asked for. An EREC G100 scheme can cap export at the permitted figure. We wrote about the limits of that in zero export, G100 and why the DNO still said no.
HV, transformers and the ICP
Somewhere above about 200 kW, depending on the local network, a low-voltage connection stops being possible and the offer names a high-voltage point of connection. That brings a transformer, a ring main unit and a metering unit, and a second contractor: an independent connection provider, or ICP, to design and build the contestable works.
The boundary sits at the outgoing terminals of the operator's ring main unit and metering unit. Everything on the solar side of that point is the customer's, including the HV circuit breaker that carries the G99 interface protection. The single line diagram must show where the protection takes its voltage reference, which relay provides the G99 functions, and which device opens to disconnect the generation.
Witness tests and the sign-off
Above 50 kW no module is fully type tested, so the site compliance and commissioning tests on Form A2-4 apply. The operator may witness them. Thresholds vary: one operator witnesses from 50 kW, most from 100 kW or 200 kW, and some charge a fee per visit. Give the notice the offer asks for, commonly 15 working days.
Then the installation document, Form A3-1, within 28 days of commissioning: the settings schedule, the as-installed data, the final circuit diagram, the commissioning checks and the declarations. Above 50 kW the operator also expects a site responsibility schedule at the interface, which records who owns, operates and maintains each item either side of the connection point.
Two further things arrive with size. Export above a modest threshold is half-hourly metered under the settlement code, and the customer, not the supplier, appoints the meter operator for it. And the export MPAN is a separate registration from the connection offer; the operator raises it, the supplier settles against it.
Questions installers ask
Is 50 kW to 1 MW Type A?
Yes. G99 Type A runs from 0.8 kW up to, but not including, 1 MW. The SAF's Parts 4 and 5 stay blank, and the Type B compliance regime in part 5 does not apply.
Can I stay under 50 kW to avoid the SAF?
Only by designing under it. A 49.9 kW three-phase inverter set is under the line and uses Form A1-1. A 60 kW inverter set down to 49.9 kW is a question for the operator, and the honest declaration shows both figures.
What is the site plan for?
The operator needs to see the boundary, the building, the array and the point of connection on one drawing to a stated scale. It is the drawing the works are priced against. A red line around the registered title is the convention.
Who signs the SAF?
The current SAF has no signature block. The covering letter and the declaration you make when you send it carry the responsibility, and the operator addresses the offer to the applicant named in Part 1, which is the customer.
Solar Engine fills the SAF's Parts 1 to 3 from the design and the lead, draws the single line diagram and the site boundary plan from the same record, and attaches all three when the CRM sends the application from your own mailbox. The fields the engine cannot know are marked for you, by owner: your company, your choice, or the site visit.