How to Run a Solar PV Installation Project: From Survey to Commissioning

What you will learn

• The six operational phases of a solar PV installation and what has to happen at each one before the next can start.
• Why pre-ordering equipment at the contract stage is the single biggest lever for compressing your project timeline by two to four weeks.
• How to distinguish G98 from G99 DNO applications and what each means for your installation schedule.
• What goes into the customer handover pack at commissioning and why it determines MCS compliance and SEG eligibility.
• How to structure the survey-to-quote handoff so no information is lost between your sales team and your installation crew.
• The failure points that generate re-work, re-surveys, and delayed final invoices across a growing project pipeline.

Running a solar PV installation business means living in the gap between what your customers see and what you actually manage. From a customer's perspective, the physical install takes one to three days. From your perspective, a residential project runs 60 to 120 days from signed contract to system activation - and every day of that is live operational work. The difference between a business that completes jobs profitably and on time and one that is always firefighting comes down to how well the phases between survey and commissioning are managed. This guide walks through each phase of a solar PV installation project, showing you where the operational leverage sits and what to have in place at each handoff.

Phase 1: The Site Survey and the Sales-to-Operations Handoff

The survey is the foundation of every solar PV installation project. Get it right and the rest of the project has a clean baseline to run from. Miss something and you will pay for it later - through redesigns, procurement delays, or installation-day surprises that push your crew off schedule.

A thorough site survey covers six core areas. Roof condition and orientation: the roof needs to be structurally sound enough for the panel array and ideally at a pitch between 20 and 50 degrees facing south, southeast, or southwest. Shading analysis: trees, chimneys, and nearby buildings that shade the array during peak generation hours affect the system design and need to be documented. Electrical panel capacity: older consumer units may not support the additional load without an upgrade, and discovering this on installation day rather than at survey adds days to the project. System sizing: based on the customer's electricity consumption (12 months of bills is the standard benchmark), you can size the array in kWp and determine whether battery storage is part of the specification. Roof access: how your crew will reach the roof safely, whether scaffolding is required, and what that adds to the job cost. Existing wiring and meter type: smart meter status and export MPAN availability affect DNO notification requirements.

The most common failure at this phase is not the survey itself - it is the handoff from the person who did the survey to the person who builds the quote and plans the installation. If survey notes live in a field engineer's notebook or a phone app that does not connect to the job record, the design phase starts without a complete picture. Every installation business needs a standardized survey checklist that travels with the job from the moment a new site visit is booked.

1. Complete a standardized survey checklist covering roof condition, orientation, shading, electrical panel, consumption data, and access requirements
2. Photograph the roof, existing consumer unit, meter, and any shading obstructions
3. Record the customer's 12-month electricity consumption in kWh from their bills or meter data
4. Transfer all survey findings to the job record before the quote is drafted - do not rely on separate notes
5. Flag any issues (roof repairs, panel upgrades, planning constraints) that need resolving before installation can proceed

Phase 2: System Design and Equipment Procurement

Once the survey data is in place, system design moves quickly. For a standard residential installation, the design produces: the panel layout and array size in kWp, inverter specification and sizing, racking system selection, battery storage specification if applicable, and a wiring schematic. This design set becomes the basis for your procurement and, in most cases, your DNO application.

The timing of equipment procurement is where most solar installation businesses leave time on the table. The standard approach is to wait until design is complete and DNO approval is received before ordering panels, inverters, and racking. That approach is logical but slow - it sequences phases that can overlap. Businesses that pre-order equipment at the contract stage, using the survey data to make confident specification decisions before the full design is finalized, routinely compress their project timelines by two to four weeks without increasing procurement risk.

Panels and inverters carry the longest lead times and the most supply variability. Inverters in particular have seen extended lead times driven by demand and import factors - some models running six to eight weeks from order to delivery. Battery storage components carry similar constraints for residential systems. Ordering against a confirmed specification as early as possible protects your installation schedule. If you wait until permit approval, you are queuing your order behind every other installer who made the same decision, and your crew availability and your equipment availability may not align when you need them to.

Raise a purchase order for each supplier at the point of commitment, not at the point of need. This creates a clear record of what was ordered, at what price, and with what expected delivery date - which matters when you are managing four or five active installations simultaneously and tracking what has arrived and what has not.

Phase 3: DNO Applications and Regulatory Compliance

Every grid-connected solar PV installation in the UK requires notification to the local Distribution Network Operator (DNO). The form of that notification depends on the size of the installation, specifically the inverter's AC output current.

For systems with an AC output under 16 amps per phase (roughly equivalent to a 3.68 kW inverter), Engineering Recommendation G98 applies. G98 installations can proceed without prior DNO approval - the installer notifies the DNO within 28 days of commissioning the system. This is the standard process for most domestic residential installations.

For systems with an AC output over 16 amps per phase - most commercial installations and larger domestic systems - Engineering Recommendation G99 applies. G99 requires you to submit an application to the DNO before installation begins. The application is more detailed, including system specifications, site plans, and a connection design. DNO assessment under G99 takes 10 to 45 working days depending on the complexity of the application and the DNO's current workload. For complex commercial systems, the timeline can extend further. If you start procurement or installation before G99 approval, you are carrying the risk of needing to modify or remove the system if the DNO's assessment requires changes.

MCS (Microgeneration Certification Scheme) certification is a separate requirement that runs parallel to DNO notification. MCS certification is required for the installation to be eligible for the Smart Export Guarantee (SEG) - the scheme under which customers are paid for electricity they export to the grid. Without a valid MCS certificate, your customer cannot apply for an SEG tariff. Your MCS certificate is issued per installation and goes into the handover pack at commissioning.

For projects that may require planning permission - installations on listed buildings, in conservation areas, or where the panels extend beyond the roof plane - confirm permitted development rights before committing to a design. Discovering a planning constraint after the design is finalized and equipment is ordered is expensive.

1. Confirm the inverter's AC output in amps per phase to determine whether G98 or G99 applies
2. For G99 projects, submit the DNO application at or before the point of equipment procurement - do not wait until installation is ready to proceed
3. For G98 projects, prepare the notification documents ready to submit within 28 days of commissioning
4. Confirm MCS certification requirements and ensure the installation meets all scheme standards before commissioning
5. Check whether planning permission is required before finalizing the design

Phase 4: Pre-Installation Checks and Installation Day

Installation day should not produce surprises. If the survey was thorough, the design is clean, equipment has arrived, and any DNO or planning approvals are in place, the installation crew should be able to execute against a clear scope with no unplanned stops.

Before confirming the installation date, run through a pre-installation checklist: permit or DNO approval confirmed (G99) or application ready (G98), all materials on site and checked against the specification, roof condition confirmed as per survey, scaffolding or access confirmed, customer has been briefed on what happens on the day and what access is needed.

On the day, the installation sequence for a standard roof-mounted residential system follows this order: scaffold or access setup, roof survey confirmation (check for any changes since the initial survey), racking installation and structural fixings, panel mounting, DC wiring from panels to inverter, inverter installation and AC wiring to consumer unit, battery storage installation if applicable, consumer unit connection and protective devices, system testing and commissioning.

Photograph every stage: racking fixings, panel positioning, inverter installation, consumer unit connection, completed array. These photographs are part of your quality record, support any warranty claims, and protect you if a customer later raises a concern about the installation. They are also required for MCS compliance documentation.

Phase 5: Commissioning, Documentation, and Customer Handover

Commissioning is the final technical step - verifying that the system generates correctly, exports safely, and is protected by the right electrical isolation and protection devices. For most residential systems this takes two to four hours on the day of installation. The commissioning checks include: PV array test (open circuit voltage, short circuit current, insulation resistance), inverter startup and generation confirmation, export limitation check if required by the DNO, and monitoring system setup and customer walkthrough.

The customer handover pack is what gets issued at commissioning and it has operational significance beyond being a gesture of professionalism. The MCS certificate in the handover pack is the document the customer needs to apply for an SEG tariff. Without it, they cannot register with an SEG licensee and cannot get paid for their exports. The DNO acceptance or G98 notification record confirms the installation is legally notified. The warranty documentation establishes the coverage periods for panels (typically 25-year performance warranty), inverter (usually 5 to 12 years), and battery if applicable. The system specification sheet records the exact equipment installed, which matters for future servicing, fault diagnosis, and insurance purposes.

A complete handover pack at the point of commissioning also enables you to issue the final invoice immediately. Delayed handover documentation is one of the most common reasons final invoices sit unpaid - the customer is waiting for their MCS certificate before they can complete their SEG application, and they hold the final payment until they have everything they need.

1. Complete PV array tests: open circuit voltage, short circuit current, insulation resistance, and record results
2. Start up the inverter and confirm live generation
3. Set up and test the monitoring system with the customer
4. Walk the customer through system operation, monitoring app, and what to do if the system goes offline
5. Issue the handover pack: MCS certificate, DNO acceptance or G98 notification form, all warranty documents, system specification sheet, and commissioning test results
6. Issue the final invoice on the same day as commissioning - do not wait

Phase 6: Building an Installation Process That Scales

Running one solar PV installation project well is a matter of execution. Running 20 active projects simultaneously - each at a different phase, with different equipment on order, different DNO application timelines, and different installation dates - is a matter of systems.

The businesses that grow consistently in this sector are not necessarily the ones with the best technical capability. They are the ones that have codified their installation process into a repeatable operational sequence and built the visibility to see where every active job sits at any given time. When a project manager can see that three jobs have equipment arriving next week, two G99 applications are at day 30 of their assessment window, and one installation needs a scaffolding date confirmed, they can plan proactively rather than chase reactively.

Standardizing each phase - survey checklist, procurement process, DNO application template, installation sequence, commissioning checklist, handover pack - removes the variability that causes rework and delay. New engineers and subcontracted crews can follow the same process without relying on tribal knowledge held by one or two senior staff. Every job follows the same path, which means exceptions get identified early rather than discovered mid-project.

Zigaflow gives solar installation businesses the structure to manage this from a single platform. Quotes are built from the survey data, jobs track each installation through the phases, works orders coordinate the installation crew, purchase orders are raised against confirmed specifications, and invoices are connected to job completion milestones so the final invoice goes out the day commissioning is signed off - not two weeks later when someone remembers to raise it.

For any solar PV installation business that has moved beyond its first handful of projects and is starting to feel the operational load of managing multiple active jobs, the process matters as much as the technical work. A well-run project is one where the customer sees a professional experience from survey to handover, your crew arrives at a prepared site, and your final invoice is paid promptly because the documentation was ready when the job was complete.

See it in Zigaflow