Value without the sales pitch
Is plug-in solar worth it?
There is no responsible universal savings number. Your result depends on where, how and when the system generates, and how much you use directly.
Published Reviewed
No calculator is currently published. We will not produce a personalised figure until the location, orientation, shading, self-consumption and tariff model is validated.
Value starts with self-consumption
A generated unit used in the home can displace a unit bought from the grid. A generated unit exported physically may have a different or unconfirmed financial value. Model those flows separately.
Where and how
Postcode, orientation, tilt, seasonal conditions and quantified shading affect output.
When you consume
Daytime appliance use determines how much generation can be consumed directly.
What energy is worth
Import tariff, time-of-use periods and any confirmed export arrangement affect the model.
Ask for comparable assumptions
A savings claim is not useful without the panel rating, postcode or climate model, orientation, shade, degradation, self-consumption share, tariff date, physical-export treatment and system cost. A future Solar Plug Scout calculator must show every assumption and a range rather than a single headline.
Simple payback, without a made-up answer
Simple payback is the total current purchase cost divided by modelled annual net benefit. Annual net benefit should separately value self-consumed generation at the applicable import tariff, include paid export only where eligibility and the export tariff are confirmed, and subtract recurring costs. If any material input is missing, the honest output is not a number.
Claims-arbitration example
A seller advertises an annual saving but does not disclose the location model, orientation, quantified shading, load profile, tariff date or whether export income was assumed. Solar Plug Scout would request those inputs, separate physical export from paid export, and test a range of self-consumption cases. No result published until those assumptions and current evidence are available; the unsupported headline is not repeated as fact.
SEG payment is not an automatic input
A model may include export payment only when the installation and installer are certified under MCS or an accredited equivalent, export metering capable of half-hourly readings is in place, and a named SEG licensee has accepted the installation. Because plug-in solar sits outside MCS's installation scope, SEG eligibility and payment for a self-installed kit are currently unconfirmed unless an accredited-equivalent route and a named supplier's acceptance can be evidenced. Otherwise it should be shown as unconfirmed or assigned zero financial value for the scenario, not described as physically impossible.
Ofgem Smart Export Guarantee: Sets out the separate scheme framework relevant to export-payment eligibility. Open source.
GOV.UK Smart Export Guarantee guidance: Sets out the certification and export metering requirements for SEG eligibility. Open source.
When plug-in solar may be a poor fit
- The available location is heavily shaded or insecure.
- Permission for mounting cannot be obtained.
- Most electricity use occurs when the system is not generating and cannot be shifted.
- The chosen product is not verified against the current register and route.
- The electrical installation or socket suitability is unresolved.
- A conventional rooftop installation is feasible and materially better suited to the household.