The 24-hour solar question: match the roof to the care day

A continuous service has a changing load

A care home operates around the clock, but its electricity demand still changes through the day. Kitchen preparation, laundry, bathing support, lighting and ventilation create different patterns. Solar generation follows another pattern, shaped by daylight and the particular roof. The useful investment question is where the two overlap. A home can have substantial annual consumption and still find that a proposed array produces electricity when little of it can be used on site. Annual totals alone cannot settle the issue.

This retrospective chapter considers the decision as it stood in mid-August and was published on 19 October. It does not transplant the DfE schools PPA pilot or its approval arrangements into care. A care provider needs the route that fits its legal entity, property rights and proposed agreement. The programme's role is to make that assessment understandable: what electricity the home could use, what expenditure it could avoid and which long-term obligations would follow.

Model the home after other planned changes

Begin with interval electricity data of known coverage and a record of the activities that explain it. Ask the designer to compare the proposed generation profile with that demand, showing the method and assumptions. Seasonal variation matters because a helpful summer overlap may not represent winter. Identify shading, roof orientation and constraints through appropriate assessment rather than treating the whole roof area as available. The output should distinguish electricity generated, electricity used on site and electricity exported.

Then consider how the home itself may change. A heating replacement could increase electrical demand; lighting or equipment improvements could reduce it; an extension or a change in occupancy could alter the pattern. Those possibilities belong in explicit scenarios. They should not be quietly added to the base case to make a larger array appear attractive. The assessment should also identify the work the building needs first. Roof repairs and electrical enabling works can affect the project sequence and its full cost.

Generation used on site is not automatically worth the complete average amount paid per unit on an historic bill. Some charges may continue after imported electricity falls, and contractual terms can affect the avoided cost. Finance should establish which costs genuinely vary with the displaced import and which remain. Export assumptions need separate treatment, including the commercial arrangement and its limitations. Combining every generated unit into one savings figure conceals the difference between avoiding an import and selling electricity elsewhere.

Keep market intelligence in its proper role

Elexon's market index provides observed wholesale price information. It is evidence about market conditions, not the home's retail tariff or a forward quotation for its next contract. ^[1] Care Circle's daily monitor can help leaders understand how volatile the background has been, while the actual investment calculation uses the provider's contract and clearly labelled scenarios. A recent high wholesale observation cannot establish that the home will avoid that price for every solar unit throughout a long agreement.

The distinction becomes especially useful when a proposal relies on future price escalation. Ask to see the result with alternative import-price assumptions, including a less favourable case, and keep those illustrations separate from observations. No one can remove uncertainty by labelling a spreadsheet forecast as intelligence. The board should understand which assumptions most influence the decision and whether the project remains acceptable when those assumptions change. A robust explanation is more valuable than a single impressive lifetime total.

Compare ownership with the whole PPA obligation

An owned installation and a PPA distribute costs and responsibilities differently. For ownership, identify capital, maintenance, insurance, monitoring and likely replacement obligations. For a PPA, establish who owns the system, how the charge changes, what electricity must be purchased and what happens to generation the home cannot use. The terms need to be read together. A low starting rate does not by itself describe the financial commitment across the term, especially where indexation or minimum purchase obligations apply.

Care property can involve separate operating and property companies, a landlord, lender or other party with relevant rights. The project team should identify whose consent is required and whose interests the documents protect. Roof access, repairs, redevelopment, a transfer of the business and an early closure can all matter over a long period. For a leased home, compare the proposed agreement with the secure period of occupation. A contract that outlives the operator's rights to the property requires careful resolution before approval.

A group can negotiate a consistent review process without treating its homes as interchangeable. One site may have a sound roof and suitable demand but uncertain occupancy; another may have strong operational prospects and a roof replacement already planned. Assess the home and the legal structure together. Explain cross-default, shared commitments or portfolio conditions where they exist. A weaker home should not be carried into a programme simply because the combined spreadsheet looks attractive, nor should a suitable single-site project require a national procurement exercise to become understandable.

Give storage a separate job to justify

A battery can be proposed for several purposes, including increasing use of solar generation or changing when electricity is imported. Define which purpose is being assessed and show the flows separately. Charging losses, operating constraints, degradation, replacement and the commercial terms all affect its contribution. Avoid adding a second savings calculation to a solar calculation if both claim the value of the same unit of electricity. A combined system needs one reconciled account of where energy comes from and where it goes.

Resilience is another distinct question. The presence of panels or a battery does not demonstrate that essential services will remain supplied in a power failure. Any proposed backup function needs an appropriately designed arrangement, with its supported loads, operating duration, testing and limitations explained. The registered manager should be involved because the consequence of an interruption depends on the service. Equipment intended mainly for a commercial energy strategy should not quietly become the home's assumed emergency provision.

The business case should therefore end with a decision about responsibilities as well as money. Who detects a fault? Who responds? How does the provider know that the expected generation was produced and the usable portion reached the home? Establish access to meter and monitoring information and a process for investigating underperformance. For an owned system and for a PPA, the ability to understand the outcome should be part of the approval, rather than a request made after the handover.

The strongest solar project is one that fits the building, the care day and the organisation's ability to manage its obligations. That judgement may support solar now, roof work followed by solar later, or a different improvement first. It should remain open to each result. After commissioning, review measured generation, imports, export income, charges and maintenance against the assumptions. Verified net expenditure is what can inform future care budgets; neither installed capacity nor a promotional projection can do that on its own.

For the next leadership meeting

Two questions to resolve.

1. How much proposed generation can this home use under its current and credible future operating patterns?
2. Which financial, property and maintenance obligations would remain if the service or its energy demand changed?