G99 commissioning form: what to complete, what to keep and what goes in the handover pack

The short answer, and why it matters

Searches around G99 split into two questions. The first is the application: what it is, what it costs, how long it takes. The second comes weeks later and is asked far less clearly: which form do I send once it is built, and what do I keep? Google suggests “g99 commissioning form a3 1”, “g99 commissioning form template” and “g99 a3-2 commissioning form”, so people are looking for it by form number.

Installer forum threads show the same confusion in plain words: whether the electrician or the owner completes the form, whether Part 2 must be filled in, whether an older system and a new battery both go on it. Those threads are not authorities and the replies disagree. The forms and the network operators’ own guidance are, and that is what the rest of this post uses.

What goes wrong without a kept record is quiet. The operator asks a question a year later, or a customer sells the house, and the only copy of the form is in an installer’s sent folder, with a serial typed from the quote rather than read from the plate.

What the form actually is, and which one you need

The Energy Networks Association publishes the G99 forms, and each network operator hosts them. The Electricity North West copy of the installation document is one file that covers Form A3-1, the installation document for Type A power generating modules, and Form A3-2, for integrated micro-generation and storage. Electricity North West’s guidance says A3-1 is submitted at the notification stage, is completed by the applicant or installer, and is completed before site commissioning or the witness test. It also says the latest version on the ENA website must be used.

Scottish and Southern Electricity Networks describe a G99 fast track route for smaller systems. There the application goes in on Form A3-3 or A1-2, and the commissioning confirmation is Form A3-2, sent within 28 days of commissioning, with one confirmation for each generating unit. Once the assessment is complete the installer has up to three months to install and commission.

MCS’s notifying page puts it simply. Solar over 16 A per phase needs prior permission, and MCS lists Form A3.1 as the form to complete, with MCS scope running up to 50 kW. A battery that falls under G99 (MCS gives over 3.68 kW with storage) needs Form A1.1 before installation, and a Type A facility also needs the combined A3-1 and A3-2 forms. Integrated solar and battery is likely G99 and fast track Form A1-2 is submitted before installation. MCS adds that some operators require their own form, so check with yours first.

What the form asks for, part by part

The ENA text of Form A3-1 is in two parts. Part 1 is completed for the whole facility and Part 2 for each power generating module being commissioned. Where an installation is phased, the form says it should be completed on a per generating unit basis as each part is finished. The table below lists what each part asks you to write down or confirm.

A checklist to keep for every G99 job

Keep these together, in one place the customer can also be given. The first item is what you receive from the operator. The next two are what you send. The rest are what you need when someone asks later.

• The approval or acceptance from the network operator, with its reference and date.
• The signed commissioning form (A3-1 or A3-2), in the version current when you used it, and the date you sent it.
• The final circuit diagram and the schedule of protection settings sent with it.
• The ENA Type Test Register reference, or Product ID, for each inverter, as entered on the form.
• The serial number of every inverter and battery, read from the plate and not copied from the quote.
• The Electrical Installation Certificate reference, and the actual commissioning date.
• The meter or grid reference, such as the MPAN, used on the application.
• Any operator question and your reply, and the date the operator acknowledged the form.

The order of work, from approval to a closed file

SurgePV’s G99 guide describes the commissioning notification as including the commissioning test results, the Electrical Installation Certificate reference, the actual commissioning date, the serial numbers of all inverters and confirmation that the protection settings match those agreed earlier. It is a vendor guide, so treat it as a useful list and check it against your operator’s forms. Followed in order, the job looks like this.

1. 1Wait for the operator’s approval. On its fast track route SSEN says you cannot connect until the assessment is confirmed complete.
2. 2Install what was approved. If a model changes on site, check with your operator whether the approval still covers it before you commission. SurgePV notes that changing agreed protection settings needs the operator’s consent.
3. 3Photograph every nameplate and read the serial from the plate. Record the as-installed capacity and date.
4. 4Complete Form A3-1 or A3-2 with the as-installed details, the protection settings schedule and the final diagram.
5. 5Carry out the commissioning checks, and only once they pass have the declaration signed by the generator or the appointed technical representative.
6. 6Send the form to the operator within the time they state (SSEN gives 28 days after commissioning for the fast track form, and MCS gives 28 days for G98 Form B; the deadline for your route is in your operator’s guidance) and keep the acknowledgement.
7. 7Give the customer a copy of the approval and the signed form in the handover pack.

Mistakes worth catching before you send

The first, third and fifth come from what the forms and the operator guidance say. The serial and kept-copy points are our own practical advice, not a rule. The fixes are cheap before you send.

• Serial typed from the quote or the delivery note. Fix: read it from the nameplate photograph.
• A missing or wrong Manufacturer’s Reference Number. ENWL calls it vitally important on its application forms, because it cannot check compliance without it. Fix: look it up on the ENA Type Test Register and copy it exactly.
• An out-of-date form. ENWL says to use the latest version on the ENA website. Fix: download it again for each job.
• A circuit diagram that is the design drawing, not the as-built. Part 2 asks for the final copy. Fix: update it before the form goes.
• One form for a phased job. The form asks for a per generating unit approach as each part is finished. Fix: complete it as each stage is commissioned.
• No kept copy. Fix: save the signed form and the acknowledgement with the job, not only in your outbox.

How a crew and an office do this with Baton

Your crew opens a link or scans a QR code and types the 6-digit job code. No account, no app to install, and it works with no signal. For each unit they photograph the nameplate, take two photos of the unit, and record its condition and where it sits. The inverter and any battery are separate lines.

Two AI models read every nameplate and a person in your office checks manufacturer, model and serial against the photo. The register is saved as a PDF, Excel and CSV in your own Google Drive. The PDF shows each unit’s nameplate and unit photographs on its own page, and the Excel and CSV carry a pointer to that page. The serial you write on the form can come from that checked register.

In the attachments index you add the G99 approval, the signed A3-1 or A3-2 and the final circuit diagram, each with a reference, a date and who issued it, using the category for grid approvals. The cover can also carry a meter or grid reference, so the MPAN sits on the same page as the equipment. Warranty dates go in per category, so the handover pack holds both.

What Baton does not do

Baton does not fill in or send the G99 form, does not contact the network operator and does not check the approval. It does not issue test reports or an Electrical Installation Certificate, and it holds no commissioning test data. Your test results, the signed form and the operator’s reply stay your own documents. Attach them to the handover so the customer receives the paper trail next to the equipment record.

The MCS Customer Commitment says the customer is given proof of notification or approval to the network provider, where needed, within 30 calendar days of completion. The attachment is how that proof reaches the pack.

Quick answers

G99 commissioning form A3-1: what is it?

Form A3-1 is the ENA installation document for Type A power generating modules. Part 1 covers the generator, installer and equipment summary, and Part 2 covers the enclosed settings, circuit diagram and commissioning checks, followed by a signed declaration. Integrated generation and storage use Form A3-2.

G99 commissioning form template or PDF: where do I get the current one?

Download the latest version from the ENA website or your network operator’s generation pages. Electricity North West says the latest version must be used, and MCS notes some operators require their own form, so ask yours before you start. Baton does not supply the form; it holds the equipment record and your attached copy.

G99 A3-2 commissioning form: who completes and signs it?

Electricity North West says A3-1 is completed by the applicant or installer. The form’s declaration is signed by the generator or their appointed technical representative. Forum posters disagree on the detail, so confirm with your network operator. Baton does not decide this; it stores the signed copy you attach.

Does Baton fill in or send the G99 commissioning form?

No. Baton does not complete or send forms and does not contact network operators. It records the equipment with photos, and lets you attach the signed form, the approval and the circuit diagram to the handover with a reference and date.

How does Baton help with G99 commissioning documents?

Your crew photographs each nameplate, a person checks manufacturer, model and serial against the photo, and the register in your Google Drive gives you serials taken from the plate. The G99 papers go in the attachments index beside it.

Sources

1. Electricity North West — G98 and G99 application guidance (which form at which stage, who completes A3-1, Manufacturer’s Reference Number)
2. Electricity North West — Installation Document, Form A3-1 and A3-2 (ENA text: Part 1, Part 2, commissioning checks, declaration)
3. SSEN — G99 fast track process (Form A3-2 within 28 days of commissioning, three months to install)
4. MCS — Notifying DNOs (G98 and G99 forms, G98 Form B within 28 days, some operators use their own form)
5. MCS — Customer Commitment, issue 1.1, 8 September 2026 (proof of DNO notification or approval within 30 days)
6. SurgePV — G99 application guide (vendor guide: commissioning notification contents, records to keep)