Commercial solar – PPA vs CapEx vs Energy-as-a-Service for UK businesses

Thesis

For most UK mid‑size enterprises the choice between buying a solar array outright, contracting a Power Purchase Agreement (PPA) or opting for an Energy‑as‑a‑Service (EaaS) model is not about technology – it is about aligning the financing structure with the balance‑sheet strategy, risk appetite and the regulatory landscape. The right route can lock in low‑carbon electricity, preserve capital for core growth and still capture the performance upside that TUS Group routinely delivers – we have already managed more than 150 GWh of flex‑enabled generation and beat supplier forecasts by 20 % over the past 12 months.

Why the funding route matters

Cash‑flow and balance‑sheet impact

A CapEx purchase ties up capital in a physical asset, creating a depreciable balance‑sheet item and a long‑term liability for maintenance. A PPA converts the upfront cost into a predictable per‑kilowatt‑hour charge, keeping the asset off the books but locking the buyer into a fixed price for 10‑15 years. EaaS bundles the asset, operation and performance guarantee into a service fee, often with a shorter contract term and the option to upgrade or scale.

Risk allocation

Ownership carries performance risk – if the array under‑delivers, the investor bears the shortfall. PPAs shift generation risk to the developer, but the buyer remains exposed to contract‑ual price risk if market electricity prices fall dramatically. EaaS providers, like TUS, assume both performance and operational risk, leveraging our 150 + GWh flex portfolio to optimise output and deliver savings that typically sit in the 5‑15 % range with a 2‑3 year payback on ancillary optimisation measures.

Regulatory incentives

The UK offers several mechanisms that affect the economics of each model:

• Smart Export Guarantee (SEG) – guarantees a minimum export tariff for small‑scale solar, payable to the owner.
• Renewables Obligation (RO) – legacy support that still influences developer pricing.
• Contracts for Difference (CfD) – primarily for large‑scale projects but informs market price expectations.
• SECR – requires quoted‑price companies to report energy use and carbon, making on‑site generation attractive for compliance.
• Climate Change Levy (CCL) – reduced for self‑generated electricity, improving the payback of owned assets.
• TNUoS and DUoS – network charges that can be mitigated through local generation, especially when combined with TUS’s voltage optimisation services (5‑15 % saving).

Capital‑expenditure purchase – owning the asset

Pros

• Full control over the system design, location and future upgrades.
• Direct entitlement to SEG tariffs and any future policy incentives.
• Depreciation benefits under UK tax rules, reducing taxable profit.
• Potential upside if electricity prices rise faster than the PPA price.

Cons

• Large upfront capital outlay – typically £1 000‑£1 500 per kW installed.
• Maintenance responsibility, even with warranties, can be complex.
• Exposure to performance risk; a poorly sited array may under‑perform.
• Asset becomes a sunk cost if the business pivots or relocates.

When it makes sense

• Companies with strong cash reserves and a long‑term horizon.
• Organisations that want to claim the full SEG export revenue.
• Sectors where carbon reporting under SECR is a material KPI.

Power Purchase Agreement – contract for supply

How a PPA works

A developer finances, installs and operates the solar array on the client’s roof or nearby land. The client purchases the electricity at a pre‑agreed price, typically 5‑15 % below the prevailing market rate, for a fixed term of 10‑15 years. The developer retains ownership and any export revenue, while the client enjoys a predictable cost stream.

Pros

• No capital expenditure – preserves cash for core activities.
• Fixed price provides budgeting certainty and hedges against volatile wholesale rates.
• Maintenance and performance risk lie with the developer.
• Often includes a “take‑or‑pay” clause that guarantees a minimum volume, protecting the developer’s financing.

Cons

• Long‑term contractual lock‑in – early termination can be costly.
• No direct entitlement to SEG tariffs or other export incentives.
• The price may be higher than a well‑optimised owned system over the asset’s life.
• Credit risk if the developer defaults.

When it makes sense

• Companies with limited capital but a strong appetite for price certainty.
• Businesses that operate in regulated cost‑of‑service environments where budgeting is paramount.
• Organisations that can’t accommodate the operational responsibilities of ownership.

Energy‑as‑a‑Service – the full‑stack solution

What EaaS delivers

EaaS bundles the solar asset, financing, installation, operation, performance monitoring and a service‑level agreement (SLA) into a single fee. TUS’s EaaS model adds our flex‑management platform, allowing the solar output to be dispatched in response to grid signals, thereby unlocking ancillary revenue streams and improving the net cash flow.

Pros

• Zero upfront cost – the fee is typically a fixed monthly charge per kW.
• Performance guarantee – TUS commits to a minimum generation level, backed by our 20 % better‑than‑forecast track record.
• Integrated optimisation – voltage optimisation can shave 5‑15 % off network charges, with a 2‑3 year payback.
• Flexibility to upgrade or relocate the system as the business evolves.

Cons

• Higher total cost of ownership compared with a pure CapEx purchase if the asset runs for its full technical life.
• Dependence on the service provider’s financial health and technical capability.
• Contract terms may be shorter (5‑10 years) but still require careful review of exit clauses.

When it makes sense

• Companies that value a predictable OPEX model and want to off‑load all operational risk.
• Organisations with ESG targets that need demonstrable carbon reduction without capital strain.
• Businesses that wish to combine solar with other flex‑enabled assets (e.g., battery storage) under a single provider.

Leasing and green loans – hybrid approaches

Leasing mirrors a CapEx purchase but spreads the cost over a 5‑10 year term, often with an option to buy at the end. Green loans, now abundant after the UK government’s Green Finance Strategy, offer lower interest rates for projects that meet sustainability criteria. Both approaches keep the asset on the balance sheet but improve cash‑flow timing.

Key considerations

• Interest rates for green loans are currently around 3‑4 % APR, compared with 6‑8 % for standard commercial loans.
• Lease agreements may include maintenance packages, reducing operational burden.
• The asset remains owned by the company, preserving eligibility for SEG and CCL relief.

Government incentives and regulatory backdrop

The UK’s policy framework continues to evolve. While the Feed‑in Tariff (FiT) closed to new applicants in 2019, the SEG remains the primary export incentive for installations up to 5 MW. The Department for Energy Security and Net Zero (DESNZ) has signalled a modest uplift to SEG rates in the 2024‑2025 period to encourage more on‑site generation.

For larger schemes, the Contracts for Difference (CfD) auction mechanism still offers a guaranteed strike price, but the competition is intense and suited to utility‑scale projects. The capacity market provides additional revenue streams for firms that can demonstrate dispatchability – an area where TUS’s flex‑management can add value by aggregating solar output with storage.

Under SECR, quoted‑price companies must report energy use and carbon intensity, making on‑site solar an effective way to improve reported metrics and avoid potential penalties. Moreover, the Climate Change Levy (CCL) exemption for self‑generated electricity can reduce annual energy costs by up to 20 % for heavy‑energy users.

Choosing the right route – a decision matrix

Criterion	CapEx	PPA	EaaS	Lease/Green Loan
Up‑front cash	High	None	None	Low‑moderate
Balance‑sheet impact	Asset on books	Off‑balance	Off‑balance	Asset on books
Performance risk	Owner	Developer	Provider (TUS)	Owner
Access to SEG	Yes	No	No (unless contract includes)	Yes
ESG reporting benefit	High	Moderate	High (provider reports)	High
Flexibility to upgrade	Low	Low	High	Moderate
Payback horizon	7‑12 years (typical)	10‑15 years contract	5‑10 years service term	5‑10 years lease

The matrix shows that a finance‑driven business with limited capital and a desire for price certainty will gravitate towards a PPA, whereas a company with strong ESG commitments and the ability to leverage TUS’s performance guarantees may find EaaS the most compelling. Pure owners still benefit from full control and the ability to capture all export revenues, but must be comfortable with the associated operational responsibilities.

Bottom line

Funding a commercial solar project in the UK is no longer a binary choice between buying or leasing. The market now offers CapEx, PPAs, Energy‑as‑a‑Service, leasing and green‑loan options, each with distinct cash‑flow, risk and regulatory implications. By aligning the financing route with your balance‑sheet strategy, ESG targets and appetite for operational risk, you can unlock the full value of solar – from reduced electricity bills to ancillary revenue via TUS’s 150 + GWh flex portfolio, which consistently outperforms supplier forecasts by 20 %. Evaluate the decision matrix, factor in the latest SEG rates and SECR obligations, and select the model that delivers the right blend of certainty, flexibility and long‑term carbon reduction.

FAQs

• Q: Can I claim the Smart Export Guarantee if I use a PPA? A: No. The SEG is paid to the owner of the generation asset. Under a PPA the developer retains ownership and therefore receives the export tariff.
• Q: How does TUS’s flex‑management improve a solar PPA or EaaS contract? A: Our platform aggregates solar output with other distributed resources, allowing us to shift generation in response to grid signals. This can generate ancillary revenue and improve the net cash flow, delivering the 5‑15 % savings we quote for voltage optimisation.
• Q: Are green loans cheaper than traditional commercial loans for solar projects? A: Yes. Current green‑loan rates in the UK sit around 3‑4 % APR, compared with 6‑8 % for standard commercial financing, reflecting the lower risk profile of certified sustainable projects.