Utah balcony ROI is a five-cell spreadsheet, not a magic online widget that still subtracts a dead 30% tax credit. Plug in kit cash, honest gross kWh, self-use share, your retail rate (start with EIA Utah 13.29¢/kWh, April 2026), and remember H.B. 340 portable export is $0. This page is the calculator method with worked rows — not a vague payback essay and not a list of bill-cutting lifestyle tips.
IRS §25D does not apply to property placed in service after December 31, 2025. ROI models that still multiply hardware by 0.7 are wrong for new place-in-service kits.
Narrative payback context: payback period balcony solar. Self-use habits after install: balcony solar optimization. Bill framing: reduce electric bill with solar.
The core formulas (copy into any sheet)
- Usable kWh/year = Gross kWh/year × Self-use fraction
- Annual $ = Usable kWh/year × Rate ($/kWh) + Export kWh × Export rate
Portable H.B. 340 path: Export rate = $0. Drop the export term. - Simple payback (years) = Kit cash (and install) ÷ Annual $
- Simple annual ROI% ≈ (Annual $ ÷ Kit cash) × 100
- Optional: raise Rate with inflation (example +2%/year) only if you want a second scenario — label it clearly.
| Input | Where to get it | Utah default if unknown |
|---|---|---|
| Kit cash | Cart total + tax + mounts + electrician | $1,100–$1,500 for many 800 W kits |
| Gross kWh/year | PVWatts or vendor estimate × shade factor | ~1,000–1,300 open 800 W; less if shaded |
| Self-use fraction | Baseload log vs production hours | 0.40–0.70 typical renter band |
| Rate $/kWh | Your bill energy charge or EIA | 0.1329 (EIA UT res Apr 2026) |
| Export $/kWh | Utility program | 0.00 portable path |
Sources: EIA Electric Power Monthly April 2026 Utah residential 13.29¢/kWh; 1st Sub. H.B. 340 (portable outside net metering); IRS §25D place-in-service end after Dec 31, 2025.
Worked rows (portable path, full sticker 2026)
| Case | Cash | Gross kWh | SU | Usable | Annual $ | Years | ROI%/yr |
|---|---|---|---|---|---|---|---|
| 400 W open, home days | $750 | 550 | 70% | 385 | $51 | ~15 | ~6.8% |
| 800 W open, mixed | $1,300 | 1,100 | 55% | 605 | $80 | ~16 | ~6.2% |
| 800 W shade, office | $1,300 | 750 | 45% | 338 | $45 | ~29 | ~3.5% |
| 1,200 W empty midday | $1,600 | 1,400 | 40% | 560 | $74 | ~22 | ~4.6% |
| 800 W + $1,000 battery, 80% SU | $2,300 | 1,000 | 80% | 800 | $106 | ~22 | ~4.6% |
Annual $ = usable × 0.1329. Rounded. Not a quote. Warranty lengths (often 10–25 years modules) matter when simple years exceed a decade.
If your sheet only looks good after you type “self-use 95%” and “export 8¢,” you are not calculating Utah portable solar — you are writing fiction. Fix the inputs before you trust the years column.
Step-by-step: fill the calculator in 20 minutes
- Cash: kit + tax + clamps + any electrician (dedicated circuit $200–$600 common).
- Gross kWh: NREL PVWatts for ZIP, tilt (90° if vertical rail), azimuth; multiply by shade factor from your photo walk (hard noon umbra often 0.5–0.7).
- Self-use: measure idle watts × daylight hours you are present; divide by expected daily kWh. Or start 0.5 and sensitivity-test 0.4 / 0.7.
- Rate: pull energy charge from RMP bill PDF; else 0.1329 as statewide average (EIA Apr 2026).
- Export: 0 for portable H.B. 340 path (≤1,200 W AC, 120 V outlet, listed, anti-islanding).
- Compute usable, annual $, years, ROI%.
- Sensitivity: re-run with +20% cash, −20% gross kWh, and self-use 0.4 to see worst reasonable case.
Shade inputs: shading impact. Size before cash: what size balcony solar. Statute: Utah portable solar law.
Common calculator mistakes (auto-fail the sheet)
| Mistake | Fix |
|---|---|
| Subtract 30% federal credit on 2026 install | Use full sticker for post-2025-12-31 in-service |
| Value 100% of gross kWh at retail | Multiply by realistic self-use |
| Assume net-meter credit on portable kit | Export rate = $0 under H.B. 340 portable path |
| Use California or national ¢/kWh | Use Utah bill or EIA 13.29¢ |
| Ignore electrician / tax / mounts | All-in cash in numerator |
| Open-roof PVWatts on a shaded rail | Apply shade factor or site photos |
| Stack >1,200 W AC as “portable” | Different legal path — interconnect model |
Optional advanced rows
- Rate inflation: Year n savings = Annual $ × (1+i)^(n−1). Sum until cumulative equals cash for simple dynamic payback.
- Inverter replacement: add mid-life cash outflow if micro warranty < module warranty.
- Move risk (renters): if lease ends in 2 years, compare remaining savings to cash — portability helps only if the next home has sun + permission.
- TOU: if enrolled in high on-peak summer rates (~30¢+ on some RMP options), value solar-hour self-use at on-peak, not at the flat average.
Decision after the numbers
| Sheet result | Interpretation |
|---|---|
| Simple years < 12, open site, SU ≥55% | Reasonable portable bill trim |
| Years 12–20 | Buy for portability/learning, not pure ROI |
| Years > 25 or > module warranty | Usually skip or fix shade/self-use first |
| Only works with fake 30% credit | Do not buy on that model in 2026 |
Run the five inputs honestly. Utah portable solar can still be worth owning — just not on a calculator that lies about export, credit, or shade.
Blank template (type over the brackets)
| Field | Your value | Notes |
|---|---|---|
| A. Kit + tax + mounts ($) | [ ] | Cart screenshot date |
| B. Electrician ($) | [ ] | 0 if shared circuit OK |
| C. Battery ($) | [ ] | 0 if none |
| D. Cash = A+B+C | [ ] | Numerator |
| E. Gross kWh/year | [ ] | PVWatts × shade factor |
| F. Self-use fraction | [ ] | 0–1 |
| G. Usable = E×F | [ ] | kWh/year |
| H. Rate $/kWh | [ 0.1329 ] | EIA default or bill |
| I. Export $/kWh | [ 0.00 ] | Portable path |
| J. Export kWh | [ ] | Usually ignore if $0 |
| K. Annual $ = G×H + J×I | [ ] | |
| L. Years = D÷K | [ ] | Simple payback |
| M. ROI% = (K÷D)×100 | [ ] | Simple annual |
Print or copy the table. Fill once with optimistic numbers and once with pessimistic (shade + office schedule). If only optimism clears a decade, the project is a lifestyle buy — price it that way emotionally, not as a bond substitute.
Sensitivity grid (800 W, $1,300 cash, 13.29¢)
| Gross kWh \\ Self-use | 40% | 55% | 70% |
|---|---|---|---|
| 700 (shaded) | $37 / 35 yr | $51 / 25 yr | $65 / 20 yr |
| 1,100 (open) | $58 / 22 yr | $80 / 16 yr | $102 / 13 yr |
| 1,300 (strong open) | $69 / 19 yr | $95 / 14 yr | $121 / 11 yr |
Cells show annual $ / simple years. Export $0. Full sticker. This grid is why shade photos and baseload logs beat brand marketing: moving left a column or up a row changes the decade count more than swapping micro logos.
Legal reminder while you optimize the sheet: portable path still needs listed hardware, anti-islanding, AC ≤1,200 W, and landlord OK. A beautiful ROI on an illegal circuit is not a finished project.
One numeric walkthrough (copy the arithmetic)
Suppose cash $1,280 (800 W kit + tax + clamps), gross 1,050 kWh/year after a mild shade factor, self-use 0.58, rate $0.1329/kWh, export $0.
- Usable = 1,050 × 0.58 = 609 kWh/year
- Annual $ = 609 × 0.1329 ≈ $80.94
- Simple years = 1,280 ÷ 80.94 ≈ 15.8 years
- Simple ROI% ≈ 80.94 ÷ 1,280 × 100 ≈ 6.3%/year
Worst re-run: gross 850, self-use 0.45 → usable 382.5 → $50.83/year → ~25 years. That single re-run decides whether you buy this season or fix the horizon first. Keep both rows in the sheet forever so a salesperson cannot delete the pessimistic column with a smile.
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