Thunder Energy plug-in solar: results, shading and projected payback
A small solar installation does not need to transform your electricity bill to be worth examining. My Thunder Energy plug-in solar system has generated about 150 kWh over approximately 119 days. Valued using my tariff at the time of recording, that represents £53.70 in savings. It is a useful early result, but it is not a full year of evidence.
The more interesting question is what happens next. These four panels are mounted vertically on a wall, and their access to sunlight changes dramatically with the seasons. Understanding that location matters as much as reading the generation total.
Why I chose a wall installation
My roof was already covered, and the pergola offered no spare space either. The roughly south-facing wall gave me somewhere else to put solar panels without needing more roof area.
This was a practical choice for my house rather than an attempt to demonstrate the best possible solar installation. The smaller panels were manageable enough for me to lift and mount individually. Larger panels might offer more generation, but their weight would change the installation job.
Mounting height was another compromise. I worked within the reach of my ladder, which left the panels lower than a position that could catch sunlight earlier. That constraint is part of the result and should stay attached to any discussion of performance.
Shading explains the autumn decline
At around 9.30 on the morning shown in the video, the panels were still shaded. A neighbouring house was blocking the sun, and the surrounding bushes also affect their winter outlook.
I used the augmented-reality view in a sun-tracking app to compare the sun’s path through the year. The summer path suggests much longer exposure. The winter path sits low enough for nearby obstructions to become a much bigger problem.
The recorded generation chart already showed output declining through September and October. At the time of recording, I expected very little generation from November through January and into the first part of February. That is an expectation based on this location, not a measured winter result or a prediction for every wall-mounted system.
What the payback projection means
The early savings represented around 8% of the system’s purchase value in my comparison. Thunder Energy supplied my system, so this is a calculation of what the savings would mean for someone paying that purchase price, rather than recovery of money I personally spent on the kit.
The video gives a projected payback of about 3.4 years. That remains a projection. Approximately four months of results cannot establish the eventual payback, especially when the installation has missed much of the summer and has a heavily shaded winter ahead.
The useful next step is to leave the configuration alone and collect a complete year of data. A consistent installation should make the eventual comparison more informative than changing the panel position midway through the test.
Living with the system
The Hoymiles inverter has needed little attention in my experience. An earlier app connection problem was attributed to a DNS issue and had been resolved by the time of this update. Home Assistant also lets me monitor generation and individual inverter inputs and bring that data into my dashboards.
For me, the appeal so far is that the system quietly gets on with producing electricity. The planned review next July should show what this particular wall installation produces across a full year. Until then, the measured savings are useful evidence, while the payback remains an estimate.
Would you favour an easier-to-reach installation, or accept a more difficult mounting position to improve sunlight?
Check out the video here https://youtu.be/pN88wR6hdBE
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