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For solar installers: independent modelling that closes deals
Independently verified system modelling for commercial solar and battery installers whose deals stall at the customer's finance sign-off.
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Commercial solar and battery deals rarely die on the engineering. They die at the customer’s finance sign-off, where the payback model behind the proposal meets someone paid to be sceptical. The problem is structural: the model was built by the party selling the system, so every assumption in it, self-consumption, price inflation, export value, is discounted as advocacy. The installer can be entirely honest and still lose, because honesty is not verifiable from inside a conflicted position.
Vester supplies the missing piece: an independently built and verified model of the proposed site, using the customer’s actual half-hourly consumption data, their real tariff structure on import and export, and honest treatment of the cost tail. The output is a finance-grade case, payback, returns, the numbers a sign-off actually turns on, produced by a party with no stake in the system size.
Why independence has to be structural
Independence is not a tone of voice; it is an incentive arrangement. Vester’s fee does not scale with the size of the system, and the model is free to conclude that the proposed design is oversized or that the battery does not stack up. That freedom is exactly what makes a positive conclusion worth something. A verification that cannot say no is a rubber stamp, and finance functions can smell a rubber stamp.
The mechanism is simple. A finance function signs off a case it can trust. A quote built by the party selling the system carries a discount for advocacy, whatever the numbers say. An independent model does not. Repositioning the deal around a verified model, rather than a sharper quote, is what carries it past sign-off.
What you get per site
For each live opportunity: a verified model built on the customer’s metered consumption, the system sized against the load rather than the roof, battery viability tested with time-of-use logic, savings shown on the current tariff and on a properly matched tariff structure, and the financial case in the form a CFO expects to sign. You present it alongside your proposal. Your customer’s finance function gets numbers it can trust; you get a deal that stops stalling.
The process runs from data, not from a site visit. You supply the customer’s half-hourly consumption history and their current tariff terms; Vester builds the model against that data rather than an assumed load profile, because assumed profiles are exactly what a finance function is trained to discount. The system design, panel count, orientation, battery size, stays yours; Vester’s role is to test that design against the metered load and report where it holds and where it does not. The output is a single document built for the customer’s finance function, which you present inside your own proposal, under your own name, with Vester’s model behind it.
A recent GP-surgery project is a working example of the process end to end. Vester ran a structured competitive tender across pre-qualified installers, comparing panel and inverter specification, battery compatibility and cycle assumptions, performance modelling, warranty structure and baseline pricing, then sized the solar system to twelve months of the practice’s half-hourly demand rather than to the roof. The result saved over £10,000 of capital on a £50,000 project, without moving off the site’s real operating profile.
Beyond the install
An install won this way seeds a longer relationship: the customer’s tariff, export arrangement and asset performance all need running after commissioning, and partners participate in that ongoing arrangement on disclosed terms. The deliberate order is model first, relationship second. The model has to earn its place on its own.
The terms are fee-based and disclosed. You pay a fixed fee per site for the model [fee to confirm]. Where a customer you introduce takes an ongoing Vester service, you earn a recurring share of the market-access cost, paid for as long as you keep serving that customer. Vester keeps none of that share, earns nothing from any supplier, and discloses your share to the customer exactly as it discloses its own fees. No hidden commission sits anywhere in the arrangement.
If you have a live deal sitting at finance sign-off, that is the best possible test. Book a conversation at /book.
Frequently asked questions
Why would I pay for a model when I already produce one with every quote?
Because your model cannot be independent, however good it is. You profit from the sale, so the customer’s finance function applies a discount to every assumption in it, and the deal stalls at sign-off. An independently verified model carries no such discount. You are not buying analysis you lack; you are buying credibility you structurally cannot supply yourself.
What if the independent model says my proposed system is too big?
Then it says so, and that is the point. A model that only ever agrees with the installer is not independent and convinces no one. In practice a right-sized recommendation is easier to win than an oversized one, because it survives the finance conversation. A smaller won deal beats a larger stalled one, and a partner who brings honest numbers is remembered for it.
How does the commercial arrangement work?
You commission the model per site on a fixed, disclosed fee [fee to confirm], and you remain the contracting party. The model supports your proposal to your customer. Where a customer you introduce later takes an ongoing Vester service, you earn a recurring share of the market-access cost as your partner share, paid for as long as you keep serving that customer. That share is disclosed to your customer to the same standard as Vester’s own fees. Vester earns nothing from any supplier and takes no commission. The rule is simple: whoever earns from the customer discloses it to the customer.