Bill Savings Simulator — annualised savings with a live tariff feed

The Bill Savings Simulator answers the year-one question a homeowner really cares about: “what will my annual electricity bill actually look like after solar?” Unlike the other calculators, it pulls the current electricity tariff live from a Eurostat feed, so the number you quote reflects today’s prices, not last year’s.

When to use it

Use it when the question is bill-shaped rather than payback-shaped — “how much will I save per year?”, “will I still owe the grid anything?” — on a first estimate call or once a customer has settled on a system size. For payback-in-years and 20-year framing, use roi-calculator instead — this tool is annualised, one year in, one number out.

How to run it

1. From your sidebar, open Pre-Sales Tools → Bill Savings.
2. Fill in monthly electricity bill (€), system size (kWp), import tariff (€/kWh) (pre-filled live from Eurostat), and export credit (€/kWh) (Greek net billing, around €0.08).
3. Results update as you type — no submit button.

Below the results, two expanders open more detail: How is this calculated? and Assumptions used — edit to refine.

What the result tells you

Four cards, updated instantly:

• Savings per month and savings per year — the reduction against the current bill
• kWh generated per year — total production for the modelled system
• Self-sufficiency % — the share of annual consumption covered by their own generation, with a progress bar below the cards

A short line also names the exported surplus in kWh, credited at the export rate you set.

The live tariff feed — what’s actually happening

The Live — eurostat, YYYY-SN badge next to the Import tariff isn’t decoration — it pre-fills from Eurostat’s semi-annual retail electricity price feed, and shows which semester you’re seeing (e.g. 2025-S2 = second half of 2025).

If the feed is temporarily unreachable, the field falls back to a stored default (€0.20/kWh for Greece) and the badge doesn’t appear. Type over the prefilled value if you have the customer’s actual tariff.

Assumptions used (and editable)

Defaults for Greek residential solar:

• 1,400 peak sun hours/year — flat Greece national average, applied everywhere regardless of postcode (unlike roi-calculator, which uses a postcode table — Crete sits around 1,750 there).
• 80% performance ratio — wiring losses, inverter efficiency, heat, dirt
• 70% self-consumption ratio — the share consumed on-site without a battery
• Export credit €0.08/kWh — mid-point of the Greek net-billing range

Edit any of these in the expander — bump self-consumption up for a customer with a battery, drop the performance ratio for a shaded roof. The output updates as you edit, but changes aren’t saved — reopening the tool resets to the defaults above.

Difference from ROI Calculator and Solar Potential

• solar-potential answers “will the roof work?” from just an address.
• roi-calculator answers “how long before it pays back?” — a horizon question with install cost baked in.
• Bill Savings Simulator answers “what’s the annual bill going to look like?” — a snapshot question, editable.

Where to go from here

• The full pre-sales toolkit: pre-sales-tools-overview
• Payback-focused counterpart: roi-calculator
• Sizing from an address before any bill talk: solar-potential