The savings a solar PPA delivers aren’t a single headline figure – they depend on three things: how much of your site’s electricity consumption the solar system covers, what you currently pay per unit from the grid, and which pricing model you opt for. Get all three working in your favour and the financial case is compelling.
This article breaks down how the numbers work, what drives them, and what a realistic saving looks like for a mid-sized commercial or industrial site.
For a full explanation of how a solar PPA is structured and what the agreement involves, see How Solar PPAs Work for UK Businesses.
What drives the size of your saving
Rooftop solar typically covers between 30% and 50% of a commercial site’s total electricity consumption, depending on roof size, system capacity, and the shape of the site’s demand profile.
A manufacturer running consistent daytime shifts will cover more of their consumption from solar than a business with heavy overnight loads. The solar electricity you generate and consume directly on-site is where the saving is greatest – you’re replacing full retail price grid with solar units at a rate set 30 to 40% below that.
The grid rate you’re currently paying is the other significant variable. A site on a high blended tariff has more headroom to save than one that has recently renegotiated a sharp supply contract. Both save money under a PPA – but differ on how much in the short term.
The two pricing models
UrbanVolt structures PPA pricing in two ways, and the right choice depends on whether your priority is maximising long-term returns or front-loading savings in the early years of the contract.
The Fixed Rate PPA locks your solar price for the full term of the agreement. As grid electricity prices rise – and over 15 years they have risen at over 6% per annum on average (DUKES, 2025) – your PPA rate stays flat. The saving per unit grows every year. For a finance director building a long-term cost reduction case, this is the stronger model: predictable pricing, a growing discount against the grid, and a total saving over the contract term that substantially exceeds what the first-year figures suggest.
The Scaling PPA starts at a lower rate that increases at a fixed annual percentage. Day one savings are higher than the Fixed Rate equivalent, whilst pricing remains fully predictable throughout. For businesses where near-term cash flow improvement is a strategic priority – or where the savings case needs to be demonstrated quickly to internal stakeholders – this model performs better in the early years, with the trade-off that total savings over the full term are somewhat lower.
Both models offer complete price transparency for the life of the contract.
What the numbers look like in practice
The figures below are illustrative, based on a medium-sized industrial site. Consumption profile, roof capacity, and current grid tariff all affect the outcome – a site-specific assessment is what produces a precise figure.
Take a site consuming 600,000 kWh annually, with a daytime profile that allows solar to cover around 40% of total consumption – 240,000 kWh per year. At an illustrative grid rate of 25p per kWh and a PPA rate fixed 35% below that, the saving on the solar portion in year one is approximately £21,000.
Grid electricity has risen at over 5% per annum on average in the UK over recent years, and there is no structural reason to expect that to change. A fixed PPA rate doesn’t move. So every year that passes, the gap between what the site pays for solar and what it would have paid from the grid widens
Over the full 20-year term, a site of this profile accumulates total savings of approximately £1.2 million against projected grid costs. That is not a rounding of the year one saving multiplied by twenty – it is what compound grid inflation actually produces when set against a rate that doesn’t move.
These are the numbers that matter to a finance director building a long-term cost reduction case. Year one justifies the decision. Years ten to twenty are why it was the right one.
Getting a real number for your site
The illustrative figures above give a working sense of the order of magnitude. To get a figure specific to your site, UrbanVolt needs your latest electricity bill and 12 months of interval data. From those two inputs, the desktop proposal models system size, estimated annual generation and consumption, PPA rate, and projected savings – both year one and cumulative over the contract term.
The proposal is the point at which the savings case becomes specific and presentable to a board or finance committee. Most businesses find the gap between the illustrative range and their actual figure is narrower than expected because the model is driven by real consumption data rather than assumptions.
About UrbanVolt
Founded in 2015, with the idea of making sustainability simple, UrbanVolt has become Ireland’s leading Solar as a Service provider and is now expanding rapidly across the UK. Backed by a team with decades of UK renewable energy experience, we help businesses cut carbon and reduce energy costs without the need for upfront investment.
Take a look at our guides, or contact us to start your journey to energy independence.