Step 1

Your numbers

Adjust these and the verdict below updates instantly.

The system

How big is the system? (kWp)

Home installs are typically 4 to 10 kWp.

Installed cost per kWp

EU about €1,200 to €1,800/kWp. US about $2,500 to $3,500/kWp before tax credits.

Government incentives or tax credits

Subtracted from the system cost.

Full price$9K

− Incentives$0

Upfront cost after credits$9K

Production

How much energy per kWp? (kWh/kWp per year)

Depends on your location and sun. Pick a preset, or look up your roof on PVGIS (EU) or NREL (US).

Performance drop per year

Panels lose efficiency slowly over time. 0.5%/year is typical.

Year 1 production: $9K kWh · you'll use 30% yourself and export the rest

Home usage & tariff

Your current electricity use per year (kWh)

Just the home, not EV charging.

Electricity price ($ per kWh)

Electricity price rise per year

Around 4%/year historically, well above regular inflation.

What % of solar production do you use yourself?

Without a battery, typically 25 to 40%. The rest is exported to the grid.

What the utility pays for surplus ($ per kWh)

Often far less than what they charge you.

Battery (optional)

Include

Battery capacity (kWh)

Battery cost per kWh

Each kWh of battery lifts self-consumption ~1% (capped at 90%).

Cars (optional)

Add a car to see how home charging an EV boosts solar's ROI, or how much an ICE car costs you in fuel today.

How long and the alternative

How many years to compare?

Investment return after inflation

What you'd earn if you invested the cash instead.

Maintenance per year

Inverter replacement year

Inverters usually need replacing around year 10 to 15.

Replacement cost

Step 2

The verdict

📉

Investing wins at these inputs

Investing beats solar by $18K

Upfront cost after credits $9K. Over 25 years you'd save $31K on electricity bills. If you'd invested that same cash at 7%, you'd have $49K. Investing wins by $18K.

The "invest alternative" compounds the upfront cash at your return for the full period. The solar side adds up each year's bill savings. In reality you'd probably reinvest solar's yearly savings too, so this comparison slightly favors the investing path. If solar still wins here, it's a strong signal.

Upfront cost after credits

$9K

Panels + install

You save in year 1

$1K

Lower bill + export payments

Pays itself off in

9 years

Over 25 years

Net gain over 25 years

$22K

Savings − costs

Total electricity produced

219,070 kWh

Over 25 years

Your yearly return

5.0%

Simple return measure

CO₂ you avoid

88 t

Compared to grid electricity

Your yearly electricity use

5,000 kWh

Home only

Year-by-year

Production falls with degradation, electricity prices climb with inflation. Cumulative savings shown against the invest-the-money alternative.

Year	Production	Self-used	Exported	Elec price	Savings	Cumulative	Invest alt.
1	9,300 kWh	2,790	6,510	$0.250	$1K	$923	$10K
2	9,254 kWh	2,776	6,477	$0.260	$1K	$2K	$10K
3	9,207 kWh	2,762	6,445	$0.270	$1K	$3K	$11K
4	9,161 kWh	2,748	6,413	$0.281	$1K	$4K	$12K
5	9,115 kWh	2,735	6,381	$0.292	$1K	$5K	$13K
6	9,070 kWh	2,721	6,349	$0.304	$1K	$6K	$14K
7	9,024 kWh	2,707	6,317	$0.316	$1K	$7K	$14K
8	8,979 kWh	2,694	6,286	$0.329	$1K	$8K	$15K
9	8,934 kWh	2,680	6,254	$0.342	$1K	$9K	$17K
10	8,890 kWh	2,667	6,223	$0.356	$1K	$10K	$18K
11	8,845 kWh	2,654	6,192	$0.370	$1K	$12K	$19K
12	8,801 kWh	2,640	6,161	$0.385	$1K	$11K	$20K
13	8,757 kWh	2,627	6,130	$0.400	$1K	$13K	$22K
14	8,713 kWh	2,614	6,099	$0.416	$1K	$14K	$23K
15	8,670 kWh	2,601	6,069	$0.433	$1K	$15K	$25K
16	8,626 kWh	2,588	6,038	$0.450	$1K	$17K	$27K
17	8,583 kWh	2,575	6,008	$0.468	$2K	$18K	$28K
18	8,540 kWh	2,562	5,978	$0.487	$2K	$19K	$30K
19	8,498 kWh	2,549	5,948	$0.506	$2K	$21K	$33K
20	8,455 kWh	2,537	5,919	$0.527	$2K	$22K	$35K
21	8,413 kWh	2,524	5,889	$0.548	$2K	$24K	$37K
22	8,371 kWh	2,511	5,860	$0.570	$2K	$26K	$40K
23	8,329 kWh	2,499	5,830	$0.592	$2K	$27K	$43K
24	8,287 kWh	2,486	5,801	$0.616	$2K	$29K	$46K
25	8,246 kWh	2,474	5,772	$0.641	$2K	$31K	$49K

Heads upThis calculator is a planning aid, not financial advice. Tax rules, visa requirements, market returns, and personal circumstances change — what you see here is a directional estimate based on your inputs. Before acting on any number, check with a qualified tax advisor, financial planner, or immigration lawyer who knows your actual situation.