Securing solar by condition when no array is shown

The situation is common enough to be routine. The Energy Statement relies on a photovoltaic array to reach the carbon reduction the local plan requires, the roof layout is not settled, and the submitted drawings show a clean roof with no panels on it. The officer is minded to approve and wants the array secured. The question is how to write a condition that will actually hold.

The short answer: secure a measurable output, tie it to the approved energy statement by date, require details before occupation rather than before commencement, and avoid any wording that lets the figure be renegotiated later.

Why the array is missing

Three reasons, and they lead to different answers.

The panel layout really is not designed yet, because the structural grid, plant locations, roof lights and fall protection zones are still moving. That is a legitimate reason for a details condition.

The applicant does not want the panels shown because they would alter the approved appearance, particularly on a scheme in a sensitive setting. That is not a good reason, and an officer who suspects it will ask for an elevational study instead.

Or the array is a contingency that nobody expects to build, included to make the percentage work. Officers have seen that often enough to look for it, and the condition they write in response tends to be the strictest available.

Say which of the three applies. An energy statement that explains why the layout is indicative, and commits to a capacity, reads very differently from one that is silent.

The six tests, applied to a solar condition

Planning Practice Guidance on the use of planning conditions sets six tests. A condition must be necessary, relevant to planning, relevant to the development permitted, enforceable, precise and reasonable in all other respects.

Enforceable and precise are where solar conditions fail. "Renewable energy shall be provided on the roof" fails both, because nobody can say what would breach it. A condition that specifies installed capacity in kilowatts peak, or a carbon saving in kilograms of carbon dioxide per year, or a roof area in m², can be checked by someone standing on the roof with the approved drawing.

Necessary matters too. Where the scheme meets the policy target without the array, the condition is not necessary and should not be imposed. That is worth saying to an officer who is attaching it as a matter of habit, which happens on schemes that already pass through fabric and services efficiency alone. The argument runs better when the baseline arithmetic is clear, and confusion about the notional building is often what makes an officer reach for a belt-and-braces condition.

Writing the condition

Three elements make a solar condition work.

A measurable performance requirement. State the minimum installed capacity or the minimum carbon saving, and reference the approved energy statement by title and date so the figure has a documented source.

A submission and approval stage for the details, covering panel layout, mounting system, inverter locations, protrusion above the roof plane, and any visual mitigation. Ask for this to be submitted before occupation or before the installation of the roof covering, depending on what the construction sequence allows.

An implementation and retention requirement, so the installation is completed before occupation and kept in place thereafter. Without the retention element the condition is satisfied the moment the panels are screwed down.

What to avoid is a clause allowing the approved capacity to be varied by agreement in writing without a further application. That is a tailpiece, and it strays into the territory the courts have treated as unlawful because it lets the permission change outside the statutory process. If flexibility is needed, ask for a range with a floor, or accept that a section 73 application is the proper route.

Pre-commencement conditions need your agreement

Section 100ZA of the Town and Country Planning Act 1990 and the Town and Country Planning (Pre-commencement Conditions) Regulations 2018 mean an authority cannot impose a pre-commencement condition without the applicant's written agreement, or without following the statutory notice procedure that produces deemed agreement if you do not respond.

That matters here. A solar details condition does not need to be pre-commencement, because nothing about the array affects the groundworks. Ask for it to bite before the roof covering is installed, or before first occupation. Officers usually agree once the point is put, and the result removes a discharge application from the critical path at the start of the build.

The same reasoning applies across the energy conditions. Charging infrastructure is routinely dealt with by condition and the trigger matters just as much, which is why the drafting of electric vehicle charging conditions is worth settling at the same time rather than separately.

Whether permitted development could deliver it anyway

Roof-mounted solar on many buildings is permitted development under Part 14 of Schedule 2 to the General Permitted Development Order 2015, subject to limits. The recurring ones are that the equipment must not protrude more than 0.2 metres beyond the plane of the roof slope and must not sit within one metre of the external edge of the roof, with exclusions for listed buildings and scheduled monuments and tighter restrictions in conservation areas and World Heritage Sites.

Two cautions before relying on that route. Permitted development rights are often removed by condition on a new permission, particularly on larger schemes, so check the decision notice you are about to receive. And an array that the energy statement counts towards a policy target is part of the development's compliance case, which means the authority has a legitimate interest in securing it rather than leaving it to a later permitted development right that could be exercised or not.

Where the array sits at ground level rather than on the roof, the permitted development position is different again and the planning consequences are more visible, so the layout belongs on the submitted drawings.

What to submit at discharge

1. A roof layout drawing showing panel positions, orientation, tilt, access and maintenance zones, and fall protection.
2. A capacity calculation demonstrating the installed kilowatts peak and the predicted annual generation, with the modelling assumptions stated.
3. Product data for the panels, mounting system and inverters, with protrusion dimensions.
4. A structural confirmation that the roof can carry the load, which on a retrofitted array is the item that stops discharge applications.
5. The connection position with the distribution network operator, including whether export is permitted and at what capacity.
6. Where visual impact was raised, an elevational or aerial view showing the array in context.

Item five is the one that surfaces late. A large array with no export capacity and a load profile that cannot absorb the generation is a technically compliant installation that wastes most of its output, and the honest fix is sometimes to size the array to demand and make up the policy shortfall elsewhere. Storage changes that arithmetic, which is why battery storage alongside a solar scheme is increasingly part of the same conversation.

Where the condition route fails

If the array cannot physically be delivered, do not secure it by condition and hope. An unenforceable promise discharged by a variation application two years later is worse for everyone than an honest position at the outset.

The alternatives are a revised energy strategy that reaches the target another way, a carbon offset payment where the local policy provides for one, or a lower on-site figure argued openly with the reasons stated. Where a Sustainability Statement accompanies the application, it should carry the same numbers as the energy statement, and divergence between the two is one of the first things a reviewing officer spots.

This is general guidance, not legal advice. Check the position with your local planning authority or a qualified professional before relying on it.

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