How we test
Real-world testing, explained.
Specifications tell you what a solar system should do. WattVerdict’s 14-day plug-in solar testing programme is designed to show what it actually does in real UK conditions.
Why 14 days?
Solar isn’t a one-day test.
A single sunny afternoon can make almost any solar system look impressive. UK weather rarely makes things that simple.
Every WattVerdict test runs for 14 days. That gives us time to see a system through changing light, cloud and weather conditions and build a much more useful picture of everyday performance than we’d get from a short demonstration or a handful of selected readings.
The test at a glance
14-day test period
Real-world output measured
Reference PV alongside every test
The complete test, not the highlights
Making the data meaningful
The weather changes. Our reference stays consistent.
This is one of the biggest challenges with real-world solar testing. A system tested during a bright June fortnight can’t simply be compared with one tested through a cloudy September using generation totals alone.
That’s why our test setup uses a consistent reference PV measurement alongside every system we test. It gives us a common view of the solar conditions available during each test, adding the context we need to make the results more useful as the WattVerdict test library grows.
What we measure
What our plug-in solar testing measures.
Our test rig records the system’s real-world output alongside the reference data needed to understand the conditions it was working in.
Actual energy generated
We measure the electricity delivered by the system during normal operation, giving us an independent record of real-world generation rather than relying solely on manufacturer specifications or app-reported figures.
Reference solar conditions
Our consistent reference PV measurement records the solar conditions alongside the system under test, helping us understand the opportunity for generation during each test period.
Performance over time
Data is collected throughout the 14-day period so we can look at the complete test rather than selecting a few favourable moments from it.
From day one to the verdict
One consistent process.
01
Set up the system
02
Collect 14 days of real-world data
03
Publish the available data through Live Testing
04
Review the complete test and publish our conclusions
What our testing means
Another layer of evidence.
WattVerdict testing adds real-world performance data to the specifications, certification and compliance information already available for a product. It isn’t a replacement for laboratory testing or formal electrical certification; it’s a practical look at how a complete system performs in everyday UK conditions.
Supplied or loaned systems
We also welcome manufacturers supplying or loaning systems for consideration for testing. Where equipment has been supplied or loaned, we’ll simply make that clear alongside the test.
See it in action
Follow the next 14-day test.
See the system currently on the WattVerdict test rig and follow its performance as the data comes in.