Screening use onlyResults are educational estimates. They are not verified for construction, equipment selection, or permit submission.· 2 registered heuristic groups (H-002 · H-020)Why

These calculators are undergoing a correctness audit against primary standards. Part of the logic still rests on engineering rules-of-thumb rather than rules traced to a dated edition of a code, and some published citations do not yet match the rule the code actually applies. Known defects are being fixed in sequence.

Treat every number here as a starting estimate to be checked, never as a design decision. Anything that will be built, energised, or submitted to an authority must be independently calculated and sealed by a licensed engineer who takes responsibility for the result.

Audit status: in progress · Assurance level: screening · Not for permit use

Rule-of-thumb decisions on this calculator

H-002 · screening only
Decision points: panel technology preset · battery chemistry preset · inverter DC/AC ratio and typical-efficiency guidelines · per-item system-loss preset · latitude tilt rule of thumb · market size catalogs and the 400 W reference module prefilled into the forms
Solar presets stand in for module, battery and inverter data the caller has not supplied; the engines label them as presets in their output, but they remain generic technology figures rather than product data.
Permit gate: block
H-020 · financial scenario
Decision points: internal-rate-of-return search domain and grid resolution
Every financial assumption — rate growth, self-consumption, degradation, discount rate, replacement cost and year, and the emission factor — is supplied by the caller and echoed back as a stated assumption; the remaining engine-chosen policy is the rate domain and resolution the IRR solver searches, which decides which rates are reportable at all.
Permit gate: requires-policy-profile

Screening use only — Results are educational estimates. They are not verified for construction, equipment selection, or permit submission.

These calculators are undergoing a correctness audit against primary standards. Part of the logic still rests on engineering rules-of-thumb rather than rules traced to a dated edition of a code, and some published citations do not yet match the rule the code actually applies. Known defects are being fixed in sequence.

Treat every number here as a starting estimate to be checked, never as a design decision. Anything that will be built, energised, or submitted to an authority must be independently calculated and sealed by a licensed engineer who takes responsibility for the result.

Audit status: in progress · Assurance level: screening · Not for permit use

Rule-of-thumb decisions on this calculator

H-002 · screening only
Decision points: panel technology preset · battery chemistry preset · inverter DC/AC ratio and typical-efficiency guidelines · per-item system-loss preset · latitude tilt rule of thumb · market size catalogs and the 400 W reference module prefilled into the forms
Solar presets stand in for module, battery and inverter data the caller has not supplied; the engines label them as presets in their output, but they remain generic technology figures rather than product data.
Permit gate: block
H-020 · financial scenario
Decision points: internal-rate-of-return search domain and grid resolution
Every financial assumption — rate growth, self-consumption, degradation, discount rate, replacement cost and year, and the emission factor — is supplied by the caller and echoed back as a stated assumption; the remaining engine-chosen policy is the rate domain and resolution the IRR solver searches, which decides which rates are reportable at all.
Permit gate: requires-policy-profile

CALC 20 · SOLARPREVIEW

Solar ROI

Payback = Net Cost ÷ Annual Savings

Build a screening cash-flow scenario from your current tariff, project quote, measured or modeled production, and explicit financial assumptions.

Solar Design Workflow

Panel SizingPanels

Inverter SizingInverter

Battery BankBattery

String ConfigStrings

5ROI AnalysisROI

Solar ROI Calculator · Advanced Preview

Available free during the correctness audit. Results remain screening-only unless the result itself states a stronger assurance level.

Current Project Evidence Required

VerElect does not supply undated tariff presets or hidden replacement-cost assumptions. Enter the effective import rate from the applicable bill or tariff and a documented inverter replacement allowance before a result is produced.

SYSTEM & COST INFORMATION

The starting figures below (system cost, size, production, maintenance, feed-in 0, incentives 0) are placeholders, not project data. Replace each with the installer quote, the production estimate from the sizing calculator and the applicable tariff; a zero feed-in tariff or zero incentive is a statement about this project, not a default.

Total System Cost ($)

$

System Size (kW)

kW

Annual Production (kWh)

kWh

Incentives/Rebates ($)

$

Government tax credits, utility rebates, etc.

Currency

Effective Import Rate ($/kWh)

Use the current effective variable rate applicable to imported energy. Fixed and demand charges require a separate billing model.

Self-Consumption: 70%

30%70%100%

Feed-in Tariff ($/kWh)

Payment for excess energy exported to grid

Annual Electricity Rate Increase: 3%

Annual Panel Degradation: 0.5%

Use the module warranty or project model.

Annual Maintenance ($/year)

Inverter Replacement ($)

Replacement Year

Grid Emissions Factor (kg CO₂e/kWh, optional)

Optional. Enter only a current factor from a traceable grid inventory.

System Life: 25 years

Discount Rate: 5.0%

Time value of money — applied to both NPV and the discounted LCOE.

Invalid Input

Solar ROI requires positive system cost/production, a valid rate, integer system life ≥ 1, and incentives within [0, system cost]

CALCULATION SHEET

— AWAITING INPUT —

Enter your system cost and production details to see your return on investment analysis.

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