Educational use only. Not financial, investment, tax or legal advice.
UK renter decision tool

Plug-in solar ROI calculator

See whether the payback beats the time left on your tenancy or lease.

Six answers. One clear recommendation. Your figures stay in this browser.

  • Free
  • No email
  • Local storage
Your setup
Updates instantly

Retail kits expected at £400–£700. Cap at £2,000.

£90
£70 cautious£110 strong

Move the slider to see how payback changes.

Buy needs at least one full year beyond the payback point.

Orientation
External modification restricted?Lease check

Adjusts the generation band. Does not change the verdict.

Saved locally. Nothing is sent to Delphina.

The decision rule

  1. Rule 1

    Skip

    No usable sun, or external changes are restricted.

  2. Rule 2

    Hold

    Orientation is marginal, or the tenancy buffer is under one year.

  3. Rule 3

    Buy

    Usable sun, permission confirmed, and at least a one-year buffer.

  4. Rule 4

    Check again

    Re-run when the price cap, your tenancy or the property changes.

Assumptions

  • Savings are illustrative and depend on shading, usage and the electricity price cap.
  • FIRE equivalent uses a 25× annual-saving shorthand, not a guaranteed investment return.
  • The August 2026 legal change does not override tenancy or lease restrictions.

Quick answers

Is plug-in solar legal in the UK?
From 27/08/2026. Installation still needs to meet current safety and tenancy requirements.
Do I need landlord permission?
Check your agreement and get written approval where external alterations or fixtures are restricted.
How much could I save?
Use £70–£110 a year as a sensitivity band, not a promise. Your actual output depends on the site.
What if I move?
Portable kits can move with you, but the new property needs a fresh orientation and permission check.

Illustrative figures, not financial or installation advice. Use a qualified electrician if in doubt.