1MW+ system
1MW+ Commercial Solar
Above 1MW, the limiting factor usually isn't roof space or cost per kWp, since both keep improving with scale. Instead, the grid connection usually becomes the real constraint at this scale. For multi-site organisations, how you sequence investment across an estate also matters, rather than treating each site alone.
Per-kWp pricing keeps improving past 1MW. But at this scale, the roof or land is rarely the constraint — the grid connection usually is. Systems in this range typically connect under the larger G99 connection categories.
That brings a fuller Distribution Network Operator study and longer lead times — often months rather than weeks. It also brings a real possibility of reinforcement cost. Since you can't know that cost until the study runs, price it into the business case at feasibility stage rather than discovering it after appointment.
The Smart Export Guarantee remains available up to 5MW. So export revenue stays part of the model even at this scale. That said, self-consumption still drives most of the return.
Capital allowances need the most careful modelling in this band. A 1MW+ system's installed cost frequently approaches or exceeds the £1 million Annual Investment Allowance ceiling on its own. This is especially likely for organisations running a wider capital programme, or a multi-site rollout. In those cases, other capital spending often absorbs the AIA in the same accounting year.
Specifically, a meaningful share of the spend typically falls to the 50% special rate first-year allowance. You then write down the remaining balance at 6% a year. That's a materially different — and slower — net-of-tax outcome than the 100% relief some marketing implies.
For estates with several sites in this range, portfolio-level sequencing matters too. Sequencing that allowance across accounting years is itself part of getting the return right.
Sources & further reading
Frequently asked questions
What's the biggest risk at this scale?
Usually the grid connection, not the roof or the capital cost. DNO capacity and G99 study timelines can add months to a programme and, occasionally, a material reinforcement cost — we check this at feasibility stage so it's priced into the decision, not discovered after appointment.
We have several sites that could each take 1MW+ — how should we sequence it?
As a portfolio decision, not a series of one-off projects: ranking sites by return and deliverability, and sequencing the rollout against both capital budget and how the Annual Investment Allowance is used across accounting years. See /services/portfolio-optimisation/.
Further reading
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Read more →Talk to us about a 1mw+ system
An initial consultation is free and carries no obligation. Tell us about your building or estate, and we'll model the real numbers for your specific site. Because every roof and load profile differs, we skip the generic range entirely.