Solar IRR Calculation 2026: Investor and Developer Guide

Every solar decision eventually becomes a finance decision. A homeowner wants to know if the panels beat the stock market. A CFO wants to know if the project clears the company’s weighted average cost of capital. A developer wants to know if the equity IRR is high enough to attract an investor. All three questions point to the same metric: Internal Rate of Return, or IRR.

Global solar capacity crossed 2.1 TW in 2025, according to the International Energy Agency’s World Energy Outlook 2024 update. At that scale, solar is no longer an environmental subsidy play. It is an infrastructure asset class with standardised financial metrics, lender expectations, and investor benchmarks. Yet IRR is still widely misunderstood in the solar industry. Installers quote simple payback. Sales teams quote ROI percentages that ignore the time value of money. Developers confuse project IRR with equity IRR and lose investors at the first meeting.

This guide fixes that. It is a practical manual for solar IRR calculation written for investors, developers, EPC contractors, and finance teams. You will learn the exact formula, the difference between project IRR, equity IRR, and MIRR, and how to build a cash flow model that survives due diligence. You will see three fully worked examples: a US residential system with the federal Investment Tax Credit, a European commercial rooftop under current tariffs, and an Indian C&I project with Accelerated Depreciation. You will also get 2026 benchmark ranges, sensitivity rules, and the mistakes that destroy credibility in investor presentations.

In this guide:

• What solar IRR calculation means and why it beats payback
• The exact IRR formula and every cash flow input you need
• Project IRR vs equity IRR vs MIRR — when to use each
• Worked example: US residential solar with the 30% ITC
• Worked example: European commercial rooftop (100 kWp)
• Worked example: Indian C&I rooftop (250 kW with AD)
• 2026 solar IRR benchmarks by market and structure
• Sensitivity analysis: the three variables that move IRR most
• Common mistakes that inflate or understate IRR
• How to calculate solar IRR in Excel and in SurgePV

What Is Solar IRR Calculation?

Solar IRR calculation is the process of finding the discount rate at which the net present value of all project cash flows equals zero. In plain language, it converts a stream of money going in and out of a solar project into a single annualised percentage return.

The mathematical definition is:

0 = CF₀ + CF₁/(1+IRR)¹ + CF₂/(1+IRR)² + … + CF₂₅/(1+IRR)²⁵

Where CFt is the net cash flow in year t. Because IRR cannot be solved algebraically, it is found by iteration — trial and error until the equation balances. Excel’s IRR function, financial calculators, and solar modeling software all do this automatically.

IRR matters because it accounts for the time value of money. A dollar saved in Year 1 is worth more than a dollar saved in Year 20. Simple payback and simple ROI ignore this. IRR does not.

For solar specifically, the cash flows are:

• Year 0: Negative CAPEX for modules, inverters, mounting, installation, and commissioning
• Years 1–25: Positive savings from avoided grid purchases, or PPA/export revenue
• Early years: Tax credits, subsidies, or accelerated depreciation benefits
• Years 1–25: Negative O&M, insurance, monitoring, cleaning, and inverter replacement
• Year 25: Residual value or decommissioning cost

A solar project with a 15% IRR is economically equivalent to an investment that compounds at 15% per year for 25 years. That makes it directly comparable to bonds, equities, real estate, or any other use of capital.

The key limitation is that IRR assumes interim positive cash flows are reinvested at the IRR rate. For high-IRR solar projects, that assumption is usually unrealistic. That is why experienced finance teams also report MIRR and NPV alongside IRR.

Why IRR Beats Payback for Solar Investors

Simple payback is the metric most often quoted in solar sales. It is easy to explain: divide net system cost by annual savings. But it is a poor tool for investment decisions because it ignores everything that happens after payback and discounts all future cash flows equally.

Consider two hypothetical 100 kWp commercial rooftop systems:

System A has a shorter payback. System B has a higher NPV and still a strong IRR because its savings grow faster after the payback year. A CFO choosing by payback would pick the wrong project.

IRR also lets investors compare solar against other asset classes on equal terms. A 15% solar IRR is directly comparable to a 15% private equity IRR or a 15% real estate IRR. Payback cannot do that.

That said, payback still has a role. It communicates risk to non-financial audiences. A homeowner who needs to recover their investment within 7 years may care more about payback than IRR. The correct approach is to present both: IRR for the investment decision, payback for the risk conversation.

For institutional investors, the comparison benchmark is the weighted average cost of capital, or WACC. A solar project clears the hurdle when its IRR exceeds WACC by a margin that compensates for execution and market risk. In 2026, WACC for European solar projects typically sits at 5–8%, so an unlevered IRR above 10% is generally attractive.

Solar IRR Calculation Formula and Cash Flow Inputs

Building an accurate IRR model means listing every cash inflow and outflow by year. The model is only as good as its assumptions. Below is the standard input framework used in investor-grade solar financial models.

1. Initial CAPEX (Year 0)

CAPEX includes every cost incurred before commissioning:

• Modules, inverters, and mounting structure
• Cables, switchgear, metering, and protection
• Civil and electrical installation labor
• Engineering, project management, and commissioning
• Permits, grid connection, and legal fees
• Financing fees during construction

Use net CAPEX after any upfront grants or immediate tax credits. For US residential solar, net CAPEX = gross cost minus the 30% federal Investment Tax Credit. For Indian C&I, net CAPEX often excludes recoverable GST input credit.

2. Annual Generation

Annual generation = system size × peak sun hours × 365 × performance ratio × degradation factor.

A 6 kW residential system in Arizona with 5.5 peak sun hours, 80% performance ratio, and Year-1 operation generates:

6 kW × 5.5 hours × 365 × 0.80 = 9,636 kWh

Apply annual degradation of 0.5–0.7% per year. Year 2 generation is 99.5% of Year 1. Year 25 generation is roughly 87–88% of Year 1.

Always use a generation estimate tied to a specific location. National averages are useful for benchmarking but dangerous for actual investment decisions. Modern solar design software combines satellite irradiance data, shading analysis, and system losses to produce bankable generation forecasts.

3. Revenue or Savings per kWh

The value of each kWh depends on who consumes it:

• Self-consumed kWh: worth the full retail grid tariff
• Exported kWh: worth the feed-in tariff, net metering credit, or export buyback rate

In 2026, European retail tariffs range from €0.28–0.35/kWh, while export rates are typically €0.06–0.13/kWh. The difference is why self-consumption ratio dominates residential and C&I solar economics.

4. Operating Expenses

Annual OPEX includes:

• Cleaning and maintenance: $10–25/kW/year for residential, $5–15/kW/year for commercial
• Inverter replacement: typically in Years 10–15
• Insurance: 0.1–0.3% of CAPEX per year
• Monitoring and administrative costs
• Land lease for ground-mount projects

O&M is often underestimated. A 1% annual OPEX error over 25 years can shift IRR by 0.5–1 percentage point.

5. Tax Effects

For taxable investors, model:

• Tax credits or rebates received
• Depreciation tax shields
• Taxable income from PPA revenue
• Tax on sale of asset or residual value

Tax effects are usually the biggest driver of early-year cash flows. India’s Accelerated Depreciation allows 40% in Year 1 plus an additional 20% in the first half-year, creating a large Year-1 shield. The US ITC reduces net CAPEX directly. Italy’s Ecobonus spreads a 50% deduction over 10 years.

6. Terminal Value

At Year 25, most models assume zero residual value or a small salvage value equal to 2–5% of original CAPEX. Including a terminal value usually adds only 0.1–0.3 percentage points to IRR, but it matters for utility-scale assets with land leases or repowering potential.

Project IRR vs Equity IRR vs MIRR

Not all IRR figures mean the same thing. Investors, lenders, and developers often quote different IRR numbers for the same project. Understanding the distinction is essential.

Project IRR

Project IRR is calculated on the total project cash flows before any debt service. The initial outflow is the full CAPEX. The inflows are savings or revenue minus OPEX and tax. Project IRR answers the question: “How attractive is the underlying asset, ignoring how it is financed?”

Project IRR is the right metric for comparing projects on a like-for-like basis. It removes leverage differences between developers.

Equity IRR

Equity IRR is calculated only on the cash flows that belong to the equity investor. The initial outflow is the equity contribution, not the full CAPEX. Inflows are savings or revenue minus OPEX, tax, debt interest, and principal repayments.

Equity IRR is almost always higher than project IRR when debt is used, provided project IRR exceeds the loan interest rate. This is the leverage effect.

For example, a project with 15% project IRR, 70% debt at 9% interest, and a 15-year term might show 22% equity IRR. The equity investor puts in 30% of the capital but earns returns on 100% of the asset.

MIRR

MIRR, or Modified Internal Rate of Return, solves a flaw in standard IRR. Standard IRR assumes positive cash flows are reinvested at the IRR itself. For a 25% solar IRR, that assumption is usually unrealistic.

MIRR lets you specify:

• A finance rate for negative cash flows
• A reinvestment rate for positive cash flows

MIRR is almost always lower than IRR. The gap depends on the reinvestment rate. At a 7% reinvestment rate, a 25% IRR might fall to 18–20% MIRR. For conservative investor reporting, MIRR is the better metric.

When to Use Each

The most credible investor presentations show all four metrics, not just the highest one.

Worked Example: US Residential Solar IRR Calculation

This example walks through a typical 6 kW residential rooftop system in California, US, with the 30% federal Investment Tax Credit. All figures are illustrative but based on 2026 market ranges.

Inputs

Year-1 Cash Flow

• Self-consumed value: 9,200 kWh × 60% × $0.32 = $1,766
• Exported value: 9,200 kWh × 40% × $0.12 = $442
• Gross savings/revenue: $2,208
• O&M: -$180
• Net Year-1 cash flow: $2,028

25-Year IRR Result

Using Excel’s IRR function on the Year 0 to Year 25 cash flow array:

• IRR: approximately 14.2%
• NPV at 6% discount rate: approximately $11,400
• Simple payback: approximately 6.2 years

The ITC is the single largest boost to IRR. Without it, the same system shows an IRR of roughly 9.5% and payback of 8.9 years. This is why US residential solar economics are highly sensitive to federal and state incentive policy.

California NEM 3.0 Impact

Under California’s NEM 3.0, export compensation rates are based on avoided cost values that vary by hour. Average export rates for residential solar have dropped to roughly $0.08–0.15/kWh, compared to the full retail rate under NEM 2.0. For a system with 40% self-consumption, this reduces 25-year IRR by 2–4 percentage points compared to older net metering.

Battery storage can partially recover this loss. A typical 10 kWh battery raises self-consumption from 40% to 65–70% but adds $8,000–$12,000 to CAPEX. The net effect on IRR depends heavily on time-of-use tariff structures and local incentives.

Worked Example: European Commercial Solar IRR Calculation

This example follows a 100 kWp commercial rooftop system in Germany, modelled with the same framework used in SurgePV’s financial modeling guide.

Inputs

Year-1 Cash Flow

• Self-consumed value: 95,000 kWh × 70% × €0.30 = €19,950
• Exported value: 95,000 kWh × 30% × €0.082 = €2,337
• Gross revenue/savings: €22,287
• OPEX: -€1,500
• Net Year-1 cash flow: €20,787

25-Year IRR Result

• Unlevered IRR: approximately 18%
• NPV at 5% discount rate: approximately €185,000
• Simple payback: approximately 5.0 years

The 18% unlevered IRR is attractive for most European corporate treasury teams. WACC for SMEs in Europe typically sits at 6–9%, so this project clears the hurdle comfortably.

The sensitivity to electricity price escalation is high. At 0% escalation, IRR falls to roughly 13%. At 4% escalation, it rises to roughly 22%. This is why every credible commercial proposal includes multiple tariff scenarios.

German Zero-VAT Note

Germany’s zero-VAT policy on solar equipment removes roughly 19% from the kit cost. For a €105,000 net CAPEX, the implied gross cost would be roughly €125,000. Without zero VAT, IRR would drop by approximately 1.5–2 percentage points.

Worked Example: Indian C&I Solar IRR Calculation

This example draws from a real project pattern documented by Heaven Green Energy’s IRR glossary. It shows why Indian commercial and industrial solar delivers some of the highest post-tax IRRs in the world.

Inputs

Year-1 Cash Flow

• Electricity savings: +₹34.5 lakh
• AD tax saving: +₹21.6 lakh
• O&M cost: -₹1.25 lakh
• Net Year-1 cash flow: +₹54.85 lakh

25-Year IRR Result

• Post-tax IRR: approximately 26.8%
• Payback: approximately 3.5–4.5 years

The AD benefit is the critical driver. Without it, post-tax IRR would fall to roughly 18–20%. With it, the project becomes one of the highest-return investments on the company’s balance sheet.

This example also illustrates why Gujarat and Rajasthan dominate Indian solar economics. High irradiance, high industrial tariffs, and a mature EPC ecosystem compress CAPEX and maximise generation value. For companies in these states, solar is usually a board-level capital allocation priority.

What Is a Good Solar IRR in 2026?

IRR targets vary by investor type, market, and financing structure. The table below summarises typical 2026 ranges. These are benchmarks, not guarantees.

Source ranges are based on investor presentations, lender models, and market reports from IRENA, BloombergNEF, and the Heaven Green Energy project database.

For a project to be considered bankable, its IRR usually needs to exceed the cost of capital by a margin. In 2026:

• Residential opportunity cost: 3–6%
• Corporate WACC in Europe: 5–8%
• Indian commercial debt + equity: 10–14%
• Institutional solar hurdle rate: 8–12%

The spread within each range is driven by four factors: local irradiance, retail or PPA tariff, incentive availability, and the investor’s tax position. A California residential project under NEM 2.0 might have cleared 18–22% IRR; the same system under NEM 3.0 often falls to 10–14% unless paired with a battery. An Indian C&I project in Gujarat with Accelerated Depreciation can reach the high twenties; the same structure in a low-tariff, low-irradiance state may barely clear 15%.

A project should be rejected when its IRR sits below the investor’s cost of capital after realistic assumptions. For a European corporate buyer with a 7% WACC, a 6% unlevered IRR destroys value even if the simple payback looks acceptable. For an Indian HNI using 10% debt, a 12% equity IRR leaves almost no margin for generation or tariff shortfall. The threshold is not universal; it is relative to the cost and risk of the capital deployed.

Sensitivity Analysis: The 3 Variables That Move IRR Most

Every solar IRR model is a stack of assumptions. The three variables below move the output more than anything else.

1. Energy Yield

A 10% reduction in generation from P50 to P90 typically reduces IRR by 2–4 percentage points. For a residential system with 14% base IRR, a P90 yield case might show 10–11%.

Yield risk comes from:

• Irradiance uncertainty
• Shading
• Soiling
• Module degradation higher than assumed
• Inverter downtime

Always run P50, P90, and optimistic yield cases. Present the P90 case to conservative investors.

2. Tariff or Electricity Price

A 1% change in annual electricity price escalation can shift 25-year NPV by 5–10% and IRR by 0.5–1.5 percentage points. Over 25 years, the compounding effect is enormous.

Most European markets have seen 3–6% average annual electricity price growth over the past decade. Conservative models use 1–2%; base cases use 2–3%; optimistic cases use 3–4%.

3. CAPEX

CAPEX changes move IRR almost one-for-one in percentage terms early in the project life. A 10% CAPEX reduction typically adds 1.5–2.5 percentage points to IRR.

CAPEX drivers include:

• Module and inverter prices
• Labor and installation costs
• Roof condition and structural upgrades
• Permitting and interconnection fees
• Financing fees during construction

Sensitivity Table Example

The table below shows how a 100 kWp German commercial project’s IRR changes across yield and tariff escalation assumptions.

The best investor presentations include a table like this. It answers objections before they are raised.

Common Solar IRR Mistakes

IRR models are easy to build and easy to break. Below are the most common errors that distort solar investment analysis.

1. Using Pre-Tax IRR for Taxable Entities

Pre-tax IRR ignores the value of tax shields. For an Indian C&I project claiming Accelerated Depreciation, pre-tax IRR might be 15% while post-tax IRR is 25%. Always report the IRR that matches the investor’s tax position.

2. Ignoring Degradation

Assuming constant generation over 25 years overstates IRR by 1–3 percentage points. Tier-1 modules degrade at 0.5–0.7% per year. Apply it every year.

3. Forgetting Inverter Replacement

Inverters typically need replacement in Years 10–15. For a 250 kW system, this can be a ₹10–15 lakh or €15,000–25,000 cash outflow. Omitting it inflates IRR.

4. Confusing Project IRR and Equity IRR

Presenting equity IRR as if it were project IRR makes leverage look like project quality. Label each clearly.

5. Using Constant Tariffs

Grid tariffs rise over time. A model with no escalation understates IRR. A model with 6% escalation forever overstates it. Use scenario analysis.

6. Omitting O&M and Insurance

O&M of ₹200–500/kW/year or $10–25/kW/year is small but persistent. Ignoring it overstates IRR by 0.5–1.5 percentage points.

7. Single-Metric Decisions

IRR alone cannot compare projects of different scales. A ₹1 lakh project at 30% IRR creates less absolute value than a ₹10 crore project at 20% IRR. Always pair IRR with NPV.

8. Reinvestment Rate Bias

Standard IRR assumes interim cash flows reinvest at the IRR rate. For high-IRR solar projects, this is unrealistic. Report MIRR for conservative analysis.

How to Calculate Solar IRR in Excel

Excel remains the most common tool for solar IRR calculation. Here is the exact workflow.

Step 1: Build the Cash Flow Array

Create two columns: Year and Net Cash Flow. Year 0 is negative CAPEX. Years 1 to 25 are savings/revenue minus OPEX and tax.

Step 2: Use the IRR Function

Enter:

=IRR(B2:B27)

Where B2:B27 contains the cash flows from Year 0 to Year 25. Excel returns the IRR as a decimal. Format as a percentage.

Step 3: Use XIRR for Irregular Dates

If cash flows occur on specific dates — for example, installation payment in March, tax credit in April, monthly savings — use:

=XIRR(cash_flow_range, date_range)

XIRR is more accurate for real-world solar projects because cash flows are rarely annual. See the XIRR solar glossary for a deeper definition.

Step 4: Use MIRR for Conservative Reporting

Enter:

=MIRR(cash_flow_range, finance_rate, reinvest_rate)

For a solar project, a typical finance rate is 6–8% and a reinvestment rate is 3–5%.

Step 5: Build a Data Table for Sensitivity

Use Excel’s Data Table feature to see how IRR changes with CAPEX, generation, or tariff. This is the standard format for investor presentations.

Solar IRR Calculation in Solar Design Software

Spreadsheet models are flexible but slow. They also create version-control risk when multiple team members touch the same file. Dedicated tools like NREL’s System Advisor Model and solar design platforms like SurgePV calculate IRR, NPV, payback, and LCOE directly from the system design.

A good solar financial tool connects the technical model to the financial model:

• Irradiance and shading analysis data feed into generation estimates
• Self-consumption modeling splits value between retail offset and export
• Local incentives and tariffs are built in by market
• Sensitivity tables update automatically when assumptions change
• Proposals export IRR and NPV alongside system designs

For installers and EPCs, this removes the gap between engineering and sales. The same model that sizes the inverter and strings the array also produces the IRR that closes the deal.

For Indian installers who also need CRM, proposal tracking, and subsidy calculations, QuickEstimate offers a mobile-first solar CRM and proposal generator. For detailed engineering and permit design support, Heaven Designs provides solar design and engineering consultancy services across 15+ countries.

IRR in Solar Project Finance: What Lenders Look For

Lenders do not rely on a single IRR number. They use IRR alongside a set of credit metrics to decide whether to finance a project and on what terms.

Debt Service Coverage Ratio (DSCR)

DSCR measures whether annual cash flow can cover debt payments. It is calculated as:

DSCR = Net Operating Income / Total Debt Service

Most solar lenders require a minimum DSCR of 1.20× to 1.35×. A DSCR below 1.0 means the project cannot service its debt from operations.

Loan Life Coverage Ratio (LLCR)

LLCR is the NPV of cash flow available for debt service divided by the outstanding debt over the loan life. It captures the entire debt period, not just one year. A typical solar project finance requirement is LLCR above 1.30×.

Debt Tenor and Sculpting

Solar loans are usually structured so that debt is repaid before major equipment replacement. A 15-year debt tenor with 25-year project life leaves a 10-year tail where the project generates unencumbered cash flow for equity. This tail equity value is a key reason leveraged solar projects can show high equity IRR.

Reserve Accounts

Lenders require debt service reserve accounts (DSRA), typically equal to 6 months of debt service, and O&M reserve accounts for major maintenance. These reserves reduce the cash flow available to equity in early years but lower default risk.

Why IRR Alone Does Not Get a Loan Approved

A project with 20% project IRR but volatile cash flows may be rejected. A project with 14% project IRR but stable offtake, strong DSCR, and a creditworthy counterparty will get financed. IRR ranks attractiveness. DSCR and offtake quality determine bankability.

For developers, the practical implication is to model both equity IRR and lender ratios from day one. A deal that looks great on equity IRR but fails DSCR at P90 generation is not a bankable deal.

Frequently Asked Questions

What is solar IRR calculation?

Solar IRR calculation is the process of finding the discount rate that makes the net present value of all solar project cash flows equal to zero. It converts upfront CAPEX, future energy savings or revenue, tax benefits, operating costs, and degradation into a single annualised percentage return that can be compared against other investments or a hurdle rate.

How do you calculate IRR for a solar project?

List every cash flow by year: Year 0 is negative CAPEX; Years 1 to 25 are annual savings or revenue minus O&M, insurance, inverter replacement, and tax. Then use Excel’s IRR function, a financial calculator, or solar modeling software to solve for the rate that makes NPV equal zero. For irregular dates, use XIRR instead.

What is a good IRR for solar in 2026?

A good solar IRR in 2026 depends on the market and structure. Residential projects typically clear 8–18%; commercial and industrial rooftop projects 15–28% post-tax with incentives; utility-scale projects 10–16%; and OPEX/RESCO consumer deals 8–12%. Most investors require the IRR to exceed their weighted average cost of capital or hurdle rate by at least 2–4 percentage points.

What is the difference between project IRR and equity IRR?

Project IRR is calculated on the total project cash flows before debt service, using the full CAPEX as the initial outflow. Equity IRR is calculated only on the equity portion invested, after debt drawdowns, interest, and principal repayments. When project IRR exceeds the loan interest rate, equity IRR is higher than project IRR because leverage magnifies returns.

Should I use IRR or NPV for solar investment decisions?

Use both. NPV tells you the absolute value created in today’s currency at a specific discount rate, which is the correct go/no-go signal. IRR tells you the annualised percentage return, which helps compare solar against other investments and communicate with non-technical stakeholders. When IRR and NPV conflict, NPV wins because it accounts for project scale and a realistic reinvestment rate.

What are the most common solar IRR mistakes?

Common mistakes include using pre-tax IRR for taxable entities, ignoring panel degradation and inverter replacement, assuming constant electricity prices, confusing project IRR with equity IRR, omitting O&M and insurance, using P50 generation without sensitivity, and ignoring the reinvestment-rate flaw in standard IRR. These errors can overstate returns by 3–8 percentage points.

How does debt financing affect solar IRR?

Debt financing splits cash flows between lenders and equity investors. Project IRR stays unchanged because it ignores debt. Equity IRR rises when project IRR is higher than the loan interest rate, because the equity investor puts in less capital upfront and earns returns on the full asset. However, leverage also raises risk: if generation or tariffs fall, debt service still has to be paid.

How do tax incentives change solar IRR?

Tax incentives accelerate returns by moving cash benefits to early years. The US Investment Tax Credit reduces Year 0 or Year 1 outflow. India’s Accelerated Depreciation creates large Year-1 tax shields. Italy’s Ecobonus spreads a 50% deduction over 10 years. Because IRR is highly sensitive to early cash flows, these incentives typically add 2–6 percentage points to IRR.

What is MIRR and when should solar investors use it?

MIRR, or Modified Internal Rate of Return, addresses the unrealistic reinvestment assumption built into standard IRR. MIRR lets you specify a separate reinvestment rate for positive cash flows and a finance rate for negative cash flows. Use MIRR when interim cash flows are large relative to initial investment, or when you want a conservative view of returns.

Can solar IRR be negative?

Yes. Solar IRR becomes negative when lifetime cash inflows are smaller than the initial CAPEX on a discounted basis. This happens with very low tariffs, extremely high installation costs, poor irradiance, systems that are drastically oversized for consumption, or markets where export compensation is near zero. A negative IRR means the project destroys value.

Conclusion: Three Actions for Better Solar IRR Analysis

Solar IRR calculation is not a black box. It is a disciplined cash flow exercise that separates credible investors from hopeful ones. The teams that win in 2026 are the ones that model with precision, present with transparency, and stress-test every assumption.

Three actions will improve your analysis immediately:

1. Model post-tax IRR with real incentives. Use the actual tax position of the investor, not a generic rate. Capture the timing of every credit, depreciation shield, and subsidy.
2. Run sensitivity on yield, tariff, and CAPEX. No single case tells the full story. Show P90/P50/optimistic yield against 0%, 2%, and 4% tariff escalation.
3. Pair IRR with NPV and MIRR. IRR communicates returns. NPV communicates value. MIRR communicates conservative returns. Use all three in investor materials.

If you want to stop building IRR spreadsheets from scratch, use SurgePV’s generation and financial tool to calculate IRR, NPV, LCOE, and payback directly from your system design. You can also explore solar proposal software to turn the model into a client-ready proposal, compare solar software pricing, or book a demo to see the workflow in action.