| Scenario | Size (kW) | Cost ($/W) | Upfront Rebate ($/W) | Credit (%) | Annual kWh/kW | Total Incentives | Net Cost |
|---|---|---|---|---|---|---|---|
| Base case | 10 | 2.80 | 0.40 | 30 | 1400 | $16,732.00 | $12,768.00 |
| Higher rebate | 10 | 2.80 | 0.60 | 30 | 1400 | $18,732.00 | $10,768.00 |
| Low production | 10 | 2.80 | 0.40 | 30 | 1200 | $16,012.00 | $13,488.00 |
- System watts: W = kW × 1000
- Gross installed cost: Gross = (W × Cost_per_W) + Soft_Costs
- Upfront rebates: Rebates = (W × Rebate_per_W) + Utility_Rebate
- Eligible basis: Basis = Gross − Rebates (if selected), otherwise Gross
- Federal credit value: Credit = Basis × (Credit_% ÷ 100)
- Loss factor: LF = 1 − (Loss_% ÷ 100)
- Annual energy: Annual_kWh = kW × (kWh_per_kW) × LF
- SREC value: SREC_Total = (Annual_kWh ÷ 1000) × Price_per_MWh × Years
- Production payments: PBI_Total = Annual_kWh × Rate_per_kWh × Years
- Total incentives: Total = Rebates + Credit + SREC_Total + PBI_Total
- Net cost: Net = max(Gross − Total, 0)
- Effective net cost: Net_per_W = Net ÷ W
- Enter system size and your installed cost per watt.
- Add soft costs for permits, design, and interconnection.
- Input upfront rebates and any flat utility incentive.
- Set the federal credit percentage used in your scenario.
- Estimate annual production and choose an appropriate loss factor.
- Include SREC price and years if credits are expected.
- Add production payment rate and duration when applicable.
- Click calculate to view incentives and net cost instantly.
- Use CSV or PDF to share results with stakeholders.
Incentive stacking for construction estimates
In construction budgeting, incentives rarely arrive as one check. This calculator stacks upfront rebates, tax credits, SREC revenue, and performance payments into one transparent worksheet. Use it early in design to compare alternatives like module upgrades, inverter choices, or roof reinforcement. Record each incentive source separately so scope changes do not hide cost risk, schedule exposure, or delayed reimbursement across stakeholders and lenders.
Cost basis and rebate timing in bid schedules
Gross cost starts from system watts multiplied by installed cost per watt, then adds permitting and other soft costs. Upfront rebates reduce cash outlay immediately, while the credit is applied to an eligible basis you can toggle. This mirrors common estimating practice where some rebates reduce basis. Keep notes on eligibility rules, labor requirements, and documentation needs in your project file for compliance.
Production assumptions that shape performance value
Energy assumptions drive performance incentives. Annual production equals system size times expected kWh per kW, reduced by a loss factor for shading, wiring, soiling, and downtime. The SREC module converts annual kWh to MWh and multiplies by price and years. Treat SREC years as contract length, not equipment life, and verify registration timing with the program administrator. Use site specific irradiance studies when available to tighten production forecasts today.
Modeling output payments under utility programs
Production payments are modeled as a rate per kWh for a fixed number of years. This is useful for utility programs that pay on measured output. If payments escalate or decline, run multiple scenarios and average the effective rate. For conservative bids, reduce the rate or shorten years to reflect policy uncertainty, curtailment risk, and meter verification delays during commissioning.
Using results for procurement and approvals
Decision support is the final output. Total incentives, net cost, and effective net cost per watt help align procurement with financial goals. Use net per watt to benchmark contractor proposals and to explain value engineering choices. Pair the net cost figure with contingency policy and cash-flow timing. Export the CSV for spreadsheets and the PDF for approval packages, audits, and lender reviews. Communicate assumptions clearly so reviewers understand what drives incentive totals most quickly.
What incentives can I include here?
Use the inputs for upfront rebates, a percentage credit, SREC sales, and production payments. If your program is different, enter the equivalent dollar-per-watt, flat, or per‑kWh value and document assumptions in the notes.
How do I estimate annual production?
Start with local kWh per kW from a reputable solar model or past projects. Apply a loss factor for shading, soiling, wiring, inverter efficiency, and downtime. Use conservative values for early estimates.
Should the credit be applied before or after rebates?
Some rebates reduce the eligible basis, while others do not. Use the checkbox to match your program guidance. When unsure, run both settings and treat the lower credit result as a conservative case.
How are SRECs calculated?
The calculator converts annual kWh to MWh by dividing by 1000, then multiplies by your SREC price and expected years of sales. Use realistic SREC years based on contract terms and market access.
What if incentives exceed the project cost?
Net cost is floored at zero to avoid negative totals. If incentives appear unusually high, recheck eligibility, caps, and timing. Many programs have maximums, step-downs, or limited annual allocations.
Can I share results with clients?
Yes. After calculating, use the CSV for spreadsheets and the PDF for a quick summary. Include your assumptions for production, loss factor, and incentive durations so reviewers can validate the estimate.