Model phase1-2026.09
How the calculator works
A deliberately simple screening estimate. It is not an engineering design, installer quote, tax opinion, or promise of savings.
Sources and policy status last verified: 2026-09-15
What we calculate
Monthly electricity use is taken directly from optional kWh input. Otherwise it is inferred from the monthly bill using the EIA Texas residential average rate. Three scenarios then estimate system size, annual production, installed cost, first-year electricity value, simple payback, and 20-year net savings.
Data Sources, Inputs, and Modeled Ranges
How published source data, user inputs, and explicit model assumptions feed into the GetSunScore calculation model.
GetSunScore Calculation Methodology Architecture:
The calculation pipeline combines published sources, user inputs, and model assumptions to generate five modeled range outputs:
Published Sources:
- PVWatts: City solar yield
- EIA: Electricity benchmark
- DOE / NREL: Installed-cost basis
Inputs & Assumptions:
- User inputs: City, monthly electricity bill, and optional electricity usage.
- Model assumptions: Self-consumption, export value, degradation, and rate escalation.
Model Engine: GetSunScore Model processes inputs deterministically across sensitivity scenarios.
Modeled Ranges Outputs:
- Cost
- Generation
- Savings
- Payback
- Net savings
Why results are ranges
A property's roof, shade, retail plan, export credit, installer price, financing, fixed charges, maintenance, and insurance are unknown. Low, base, and high scenarios expose those uncertainties instead of presenting false single-dollar precision.
Scenario assumptions
| Input | Low | Base | High |
|---|---|---|---|
| Target generation vs. use | 65% | 80% | 90% |
| Production factor | 90% | 100% | 110% |
| Installed cost | $3.12/W | $2.95/W | $2.78/W |
| Self-consumed share | 55% | 70% | 85% |
| Export value vs. retail | 30% | 50% | 70% |
| Annual degradation | 0.7% | 0.5% | 0.3% |
| Annual rate escalation | 0% | 1.5% | 3% |
Scenario bands are model choices for sensitivity testing, not forecasts or installer quotes. DOE's national Q1 2025 residential PV-only MSP ($2.78/Wdc) and MMP ($2.95/Wdc) anchor the cost sensitivity. The $3.12/Wdc high-cost input is not a DOE-published benchmark; it is derived symmetrically as MMP + (MMP - MSP). These are national modeled inputs, not Texas-specific market quotes. The electricity-rate baseline is 15.94¢/kWh from EIA.
SunScore
SunScore summarizes estimated economics on a 0–100 scale: 55% simple payback, 25% modeled consumption coverage, and 20% annual solar yield. Payback is normalized from 25 years (weak) to 8 years (strong), coverage from 50% to 90%, and yield from 1,200 to 1,700 kWh per installed kW-year.
- 0–39: weak estimated economics
- 40–59: marginal economics
- 60–79: potentially attractive
- 80–100: strong estimated economics
The score is a comparison aid, not an engineering certification or guarantee.
Incentives
No incentive is automatically deducted. Current policy information is informational and eligibility varies by taxpayer, property, and application facts. The federal residential Section 25D credit is marked ended for expenditures after December 31, 2025. The Texas property-tax exemption may apply but requires an application and appraisal-district determination.
Residential Clean Energy Credit (Section 25D)
Jurisdiction: United States. Effective: 2022-01-01 to 2025-12-31. Automatically applied: no.
The credit applied to qualifying expenditures through December 31, 2025. Eligibility depends on taxpayer facts and applicable law.
Policy review: verified · reviewed 2026-09-15 · source checked 2026-09-15
Solar and Wind-Powered Energy Device Property Tax Exemption
Jurisdiction: Texas. Effective: 1982-01-01 to no end recorded. Automatically applied: no.
Qualifying owners must apply through the applicable appraisal district, whose chief appraiser determines eligibility.
Policy review: verified · reviewed 2026-09-15 · source checked 2026-09-15
What we do not calculate
- Roof plane, shade, structural condition, or equipment design
- Exact utility tariff, fixed/non-bypassable charges, or a guaranteed export rate
- Financing fees, interest, tax consequences, insurance, maintenance, or resale value
- Installer availability, interconnection approval, or property-specific production
Sources
U.S. Energy Information Administration · reporting period 2026-06 · retrieved 2026-09-15 · status: stale · stale after 90 days
8 kWdc rooftop PV-only reference · 2024 real USD · storage and customer incentives excluded · reviewed 2026-09-15 · status: verified · annual human review
National Laboratory of the Rockies · source date 2026-09-15 · scope: 15 Phase 1 Texas incorporated places · verified 2026-09-15
Internal Revenue Service · source date 2026-09-15 · scope: United States federal tax law · verified 2026-09-15
Texas Comptroller of Public Accounts · source date 2026-09-15 · scope: Texas property tax · verified 2026-09-15