Commercial solar tenders, ITT responses and procurement support

Most large solar projects move through a recognised sequence, whether or not your organisation is bound by public procurement rules.

The process usually opens with a PQQ or Selection Questionnaire, which qualifies bidders on financial standing, insurance, health-and-safety record and relevant experience before any design work begins. Qualified bidders then receive the Invitation to Tender or Request for Proposal, which contains the specification, the scope, the contract terms and the scoring method. Bidders respond with a technical proposal and a price, the responses are evaluated against published criteria, and a contract is awarded. Public bodies frequently run this through a framework, a pre-procured panel of suppliers that removes the need to run a full open tender each time and gives a compliant route under the Procurement Act 2023.

The part that most affects the outcome is the evaluation split. A tender scored purely on price drives bidders towards the cheapest panel, the thinnest design effort and the smallest commissioning scope, because that is what wins. A most economically advantageous tender split, where quality and whole-life value carry real weight alongside price, rewards a bidder who has actually surveyed the building and modelled the load. We respond best to the second kind, and the rest of this page is written to help you write one.

A strong specification makes every bidder price the same engineered system, so the prices you compare mean something. These are the clauses that do that work.

An evidenced design rather than a panel count. Ask for the system to be sized from a site survey and a yield model, with the assumptions stated. We size from an on-site 3D drone survey and model the array in PV*SOL against your half-hourly consumption data, so the generation figure in the bid is specific to your building. A bidder who cannot show how a figure was reached has guessed it.

Half-hourly load modelling. The value of a commercial system is set by how much generation you use on site versus export, and that is only knowable from your half-hourly demand profile. Require it in the specification, supply your data, and ask each bidder to state the modelled self-consumption. A bid that skips this cannot have priced the return honestly.

Bankable, named modules. Ask for the panel to be named by manufacturer and model, with its bankability evidence stated: the BloombergNEF Tier 1 list it appears on and the quarter of that list. Tier status is periodised, so naming the quarter and re-verifying before contract is what keeps the claim honest. This stops a bidder swapping to an unknown panel after award.

A compliant grid design under G99. A system this size connects under ENA Engineering Recommendation G99, assessed by your Distribution Network Operator, which across Yorkshire and North and North-East Lincolnshire is Northern Powergrid. Require the bidder to set out the connection route and any export limitation, because the connection can shape both the cost and the timetable. Our how-we-quote process covers where this sits in the design.

Commissioning to BS 7671 and IEC 62446-1. Specify that the installation is designed and tested to BS 7671, the wiring regulations, and commissioned and documented to IEC 62446-1, the standard for grid-connected PV system documentation, commissioning tests and inspection. Require the test certificates and the handover pack as deliverables. This is the evidence the system was built and proven correctly.

CDM 2015 duties named. A commercial install is construction work, so the Construction (Design and Management) Regulations 2015 apply. Ask each bidder to state its duties and how it will discharge them. A bidder who does not mention CDM 2015 on a project this size is a concern.

An Insurance-Backed Guarantee and a real O&M scope. Require an Insurance-Backed Guarantee so the workmanship warranty survives the installer, and ask for a defined operations-and-maintenance scope with response times, not a line that says maintenance is included. Our design and engineering page sets out the documented pack these deliverables come from.

Note what is deliberately absent from that list: MCS. MCS is the domestic microgeneration certification scheme and does not apply to systems above 50 kWp, so requiring it in a commercial ITT excludes the engineering-led firms best suited to the work. Our guide to quality without MCS sets out the standards that do apply.

When you evaluate the responses, a few patterns reliably mark a bid that has not done the engineering.

A from-price or a cost per kWp with no survey. A figure quoted before anyone has been to the building cannot reflect your roof structure, your shading or your connection, and a per-kWp rate hides what is actually included. A real commercial price follows a survey and a model. We do not publish a from-price for this reason, and a bid that leads with one has priced a generic system rather than yours.

An MCS claim. A bidder citing MCS certification on a system above 50 kWp has either misunderstood the scope of the scheme or is using a domestic trust badge where it does not apply. Either way it tells you the engineering framework for this scale is not where their attention is.

No half-hourly load modelling. If a bid states a saving or a payback without showing the self-consumption it is built on, the number is unsupported. The whole economic case for commercial solar turns on how much generation is used on site, and that is only knowable from the half-hourly profile. Our guide on choosing a commercial installer goes deeper on what to test for.

An undisclosed panel or a substitution clause. A bid that will not name the module, or that reserves the right to substitute it after award, is keeping the option to fit something cheaper later. The specification should close that door, and the evaluation should mark down any bid that leaves it open.

We respond as an engineering-led firm, which means the proposal is built from the building rather than dropped onto it.

A documented design pack. Where the timetable and access allow, our response is built on an on-site 3D drone survey by our own fully insured in-house pilot and a PV*SOL yield model run against your half-hourly load. That gives a generation and self-consumption figure specific to your site, with the assumptions visible, rather than a figure carried in from another job. The pack and the method behind it are set out on our design and engineering page.

The non-MCS assurance stack, stated in full. Because the system sits outside MCS, we assure it through the framework that applies at this scale: a design and installation to BS 7671, commissioning and documentation to IEC 62446-1, a grid connection under G99 with the DNO, CDM 2015 duties discharged across the construction phase, and an Insurance-Backed Guarantee on the workmanship. We name these in the response so the evaluator can score the engineering directly.

The whole-life view. Our response covers the operations-and-maintenance scope and the funding context, so a finance team can read it as a whole-life case rather than a single headline figure. The economics route to the commercial finance pages rather than a single quoted figure, because the right number for your organisation depends on your tariff, your load and your funding route.

A note on status, stated plainly. Alectrona is the commercial trading identity of RVTC Installations Ltd, an engineer-led firm. What we bring to a tender is the engineering: the survey, the model, the documented design pack and the non-MCS assurance standard described above.

The procurement route varies by the kind of body running it, and the detail of each sector sits on its own page.

For local authorities, the tender usually runs through a framework or a compliant open process under the Procurement Act 2023, often tied to a net-zero or estate-decarbonisation target. For NHS bodies, procurement is shaped instead by the Greener NHS programme and by the operational constraints of a live clinical site. Our public-sector and councils page covers both, from the estate and reporting context through to the Health Technical Memoranda and permit-to-work rules that govern work over occupied wards. For academy trusts and schools, the route runs through trust procurement and the relevant education frameworks, with funding routes that differ from the commercial market, set out on our schools and academies page. Universities and housing associations typically run their own formal tenders with sustainability weighting built into the scoring.