Helios

What it does

Helios estimates how much electricity a plug-in solar panel could generate at a specific UK address and calculates payback time against the homeowner's electricity tariff. The tool uses government LIDAR data to model the surrounding skyline—buildings, hills, trees—to predict how much shade will fall on the installation. Users enter their postcode, floor level, balcony direction, annual electricity consumption, and electricity tariff. The tool then returns an estimated annual generation in kWh and a payback period in years.

Who it is for

The tool is designed for UK homeowners and flat dwellers considering whether to install plug-in solar panels. These are DIY-friendly installations that require no electrician or planning permission. The tool helps them decide whether a small system—typically 0.4 kWp or 0.8 kWp—makes financial sense for their specific property and energy use.

Pricing

The site does not show prices.

How it stands out

Most solar calculators use generic orientation and weather data. Helios builds its estimates on actual LIDAR data from the UK government, accounting for local obstructions that block sunlight. This specificity matters: a panel on a south-facing balcony surrounded by taller buildings will generate far less than the same panel in an open location. The tool also asks for the user's actual electricity tariff—from major suppliers like EDF, British Gas, and Octopus—to estimate savings rather than just raw generation. It explicitly addresses the Smart Export Guarantee quirk: most DIY plug-in kits cannot achieve MCS certification, so owners earn nothing for power exported to the grid; the value lies entirely in self-consumption. The calculator defaults this export rate to zero and asks users to override it only if they have a certified install.

What a founder should check

First, verify the accuracy of payback estimates against real-world installations post-2024. LIDAR data has known gaps (most of Scotland and Wales, post-2022 developments, and recent tree growth), and the tool's fallback to synthetic horizons in uncovered areas introduces error; test how often users are in degraded-data zones. Second, investigate switching costs and switching pressure: once a homeowner has purchased a kit and installed it, what locks them into Helios versus building a spreadsheet or using a competitor's calculator next time? The tool stores no address data, so there is no account lock-in. Third, watch incumbent players—established solar firms and energy suppliers may launch their own calculators to drive sales directly, using superior customer data they already hold.