Coastal UK (illustrative)

Illustrative Model: Coastal Cottage With a Hot Tub and Battery

Property

Illustrative model

System

6 kW roof array + 10 kWh battery (indicative)

Annual generation

5,400 kWh (indicative)

Annual saving

Indicative only, not a quote

Indicative payback

9 years

Read this first: an illustrative model, not a real customer

This is an illustrative worked example, not a real named customer and not a quote. We have built it to show how the numbers behave for a very common holiday-let shape, a single coastal cottage with a hot tub, so that you can see the shape of the economics before your own property is modelled. Every figure below is indicative and modelled, scaled from small-domestic cost-per-kW assumptions rather than drawn from a specific install. It is a scoping illustration, and it is clearly labelled as such throughout. For a genuine, independently reported case, see our real Highland Farm Cottages study instead.

The modelled property

The illustration is a single coastal self-catering cottage with a hot tub, off the gas grid on electric heating, running roughly 85% occupancy across the April-to-October season. This is a deliberately representative property: the coastal, off-gas-grid, hot-tub-equipped cottage is one of the most common holiday-let shapes in the UK, and it sits squarely in the profile where solar and battery earn their keep. The modelled owner’s goals are ordinary ones: cut the season’s electricity bill, and stand out on sustainability in the listing.

The modelled system

For this property an installer should model a 6 kW roof array with a 10 kWh battery, an indicative configuration toward the middle of the range for a single cottage. That array generates in the region of 5,400 kWh a year in an indicative UK coastal setting. A coastal position would in practice call for a salt-resistant specification on the mounting and fixings, which is a design detail rather than a cost driver at this scale.

The 6 kW array size is chosen to match a hot-tub-and-hot-water daytime load without over-generating into a low-value export tariff, and the 10 kWh battery is sized to time-shift the evening demand that a cottage carries after the sun is down.

How the numbers are modelled to behave

The point of the illustration is the seasonal match. Across the busy April-to-October season, the cottage’s largest loads, the hot tub kept hot for back-to-back guests, and the hot-water re-heat at every changeover, draw power in the same months and largely the same daylight hours that the array generates most. That is modelled to give a high in-season self-consumption, with the array covering the bulk of the daytime hot-tub and hot-water demand directly.

The battery then time-shifts the rest. Midday generation that is not used immediately is stored and released in the evening and overnight, keeping the tub hot for new arrivals and re-heating water for the changeover, instead of buying peak-rate grid electricity after dark. That evening time-shift is where much of the modelled return comes from on a hot-tub cottage.

In the quiet winter, when the cottage is lightly occupied, surplus generation is modelled as exported to the grid under the Smart Export Guarantee, earning on power the cottage was not going to use. Holiday lets export meaningfully in exactly the off-season months when most homes are drawing hardest, which is part of why the seasonal profile suits solar.

The modelled payback

On these assumptions the illustration models to an indicative payback of around nine years, with the figure improving where a hot tub runs harder and where guest EV charging is added to lift daytime self-consumption further. We show nine years as the central indicative figure for a single hot-tub cottage; a hot-tub-free property would model longer, and a lodge with heavier hot-tub and EV load would model shorter, which is why our lodge and cabin page carries a faster indicative figure.

To be explicit about what this is and is not: the nine-year payback here is a modelled illustration for scoping, not a quote, not a guarantee and not drawn from a named customer’s real install. Your own figure depends entirely on your tariff, your hot-tub and EV load, your occupancy calendar and your roof.

What to do with this illustration

Use it to understand the mechanism, not to price your project. The mechanism is genuine and it is the core of the holiday-let case: a hot-tub cottage’s biggest loads fall in the sunniest, busiest months, high in-season self-consumption captures most of the value, a battery time-shifts the evening demand, and off-season export tops it up under the Smart Export Guarantee. That pattern holds for real properties even though this specific set of numbers is a model.

When you want the same logic applied to your own cottage with real figures rather than an illustration, send an enquiry and an installer should model it from your consumption and your occupancy. For how these numbers are built up and what moves them, see our cost guide, and for the tax position after the April 2025 Furnished Holiday Lettings change, our grants and funding routes page sets out the honest position, take your own tax advice. For the full sector picture across cottages, lodges, glamping and parks, start from the solar panels for holiday lets hub.