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📄 Tool Explainer · PVsyst Analysis

How to Use the PVsyst Loss Audit & What-If Tool

A step-by-step guide to uploading your simulation report, auditing every loss, and running what-if scenarios that change how you design and negotiate solar projects.

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Every PVsyst report contains a loss diagram that tells you exactly where your energy goes — from irradiance on the modules all the way down to kWh injected into the grid. This tool turns that static diagram into a live, interactive what-if engine. Change any loss by moving a slider and instantly see the GWh and revenue impact across 25 years.

Whether you’re a project developer optimising a design, an O&M team benchmarking actual performance, or a lender scrutinising an energy yield report — this tool gives you the numbers you need in seconds, not spreadsheet-hours.

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What Is the PVsyst Loss Diagram?

PVsyst produces a cascading energy loss diagram on page 7 of every simulation report. It starts with the total solar resource hitting your modules (in GWh) and subtracts each loss one by one until you reach E_Grid — the energy actually exported to the grid.

The Ottapidaram 125MW Example This tool is pre-loaded with data from a real 162.5 MWpdc / 125 MWac plant in Tamil Nadu. Nominal STC energy is 294.92 GWh/yr. After all losses, E_Grid = 253.82 GWh/yr — a 14% reduction from nameplate. Knowing where those 41 GWh go is the entire point.

The tool automatically parses all 16 loss parameters from your uploaded PDF — including the exact values from the loss diagram lines like -0.6% Unused energy (grid limitation) and -1.4% Inverter Loss during operation (efficiency).

At a glance, the tool gives you:

• 16 loss parameters parsed directly from the loss diagram on page 7
• Live recalculation — every slider update recalculates GWh, ₹ Crore, PR, and specific yield
• 25-year projection built in, with degradation and tariff inputs
• P50 / P75 / P90 exceedance scenarios switchable in one click
• Monthly breakdown — delta GWh and revenue for every month of the year
• CSV export for all parameters and results

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Step-by-Step: Using the Tool

Step 1 — Upload Your PVsyst Simulation Report

Click the upload zone or drag and drop your PVsyst PDF directly onto it. The tool accepts any PVsyst V6, V7, or V8 report for grid-connected systems, including bifacial configurations.

The parser reads page 7 (Loss Diagram) line by line, looking for every ±X.X% label pattern and mapping it to the correct parameter. Bifacial geometry values like View Factor for rear side (−39.1%) are automatically skipped — these are geometric correction factors, not energy losses.

Project metadata is extracted from pages 1–4: project name, location, DC/AC capacity, DC:AC ratio, module model, inverter model, nominal STC energy, P50/P75/P90, specific yield, and Performance Ratio.

Monthly generation data — GlobInc, EArray, and E_Grid for each month — is read from the balances table on page 6.

Note: If your PDF uses a non-standard layout, the parser falls back to the Array Losses table on pages 3–4, then to built-in demo data for any missing values. The parsing log shows you exactly what was found and what defaulted, so you always know what was extracted vs assumed.

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Step 2 — Set Your Financial & Exceedance Assumptions

Once the tool loads, the yellow assumption bar appears below the project ribbon. Set four inputs that drive all revenue calculations:

Tariff (₹/kWh) — Enter your PPA or APPC rate. Default is ₹3.20/kWh. All revenue figures — annual ₹ Crore and 25-year lifetime — update live whenever you change this value.

Degradation (%/yr) — Module degradation applied annually over the project life. Default is 0.5%/yr, which is standard for modern bifacial modules. Higher values reduce lifetime revenue significantly over a 25-year horizon.

Project Life (years) — Used for the 25-year projection chart and the lifetime revenue KPI card. Set this to your PPA term or expected asset life.

P50 / P75 / P90 — Toggle the exceedance scenario. P90 is the conservative lender’s case — energy exceeded 90% of years. P50 is the median case used for owner’s projections. All KPI cards and charts update immediately when you switch.

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Step 3 — Adjust Loss Parameters with the Sliders

The Loss Parameters panel contains all 16 loss parameters organised in four groups. Each slider shows the PVsyst baseline value as a blue badge. Drag the slider to change the value — the badge turns red/peach if you’ve made the loss worse than PVsyst’s assumption, and green if you’ve improved it.

Irradiance Losses

• Near Shadings: irradiance loss — Ottapidaram: 0.4% | Typical range: 0.2–1.5%
• Soiling loss factor — Ottapidaram: 1.0% | Typical range: 0.5–4.0%
• IAM factor on global — Ottapidaram: 2.3% | Typical range: 1.5–4.0%
• PV loss due to irradiance level — Ottapidaram: 0.4% | Typical range: 0.2–1.0%

DC Array Losses

• PV loss due to temperature — Ottapidaram: 5.9% | Typical range: 3.0–9.0%
• LID — Light induced degradation — Ottapidaram: 1.0% | Typical range: 0.5–2.0%
• Mismatch loss, modules and strings — Ottapidaram: 0.9% | Typical range: 0.5–2.0%
• Ohmic wiring loss — Ottapidaram: 0.3% | Typical range: 0.2–1.5%

Inverter Losses

• Inverter Loss during operation (efficiency) — Ottapidaram: 1.4% | Typical range: 0.8–2.5%
• Inverter Loss over nominal power (clipping) — Ottapidaram: 0.1% | Typical range: 0.0–3.0%

AC & System Losses

• Auxiliaries (fans, other) — Ottapidaram: 0.5% | Typical range: 0.3–1.0%
• AC ohmic loss — Ottapidaram: 1.1% | Typical range: 0.5–2.0%
• Medium voltage transfo loss — Ottapidaram: 1.1% | Typical range: 0.5–1.5%
• MV line ohmic loss — Ottapidaram: 0.2% | Typical range: 0.1–0.5%
• System unavailability — Ottapidaram: 1.0% | Typical range: 0.5–3.0%
• Unused energy / Grid curtailment — Ottapidaram: 0.6% | Typical range: 0.0–5.0%

The impact tag next to each slider shows how many GWh that parameter contributes to the current scenario. When you modify a parameter, it also shows how many GWh you have gained or lost compared to the PVsyst baseline.

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Step 4 — Read the Six KPI Cards at a Glance

The six KPI cards at the top of the tool update instantly as you move any slider. Each shows both the adjusted value and the delta vs your chosen baseline.

Adjusted Generation — Total annual E_Grid after all your modified losses, in GWh/yr. Green delta means better than baseline, red means worse.

Delta vs Baseline — The net GWh gain or loss vs the PVsyst exceedance scenario. This is your headline number for any negotiation or review document.

Annual Revenue — GWh × tariff × 10 = ₹ Crore per year. Adjusts live with both generation changes and your tariff input.

Lifetime Revenue — Cumulative ₹ Crore over your entire project life, compounded by the annual degradation rate you’ve entered. The delta shows exactly how much your scenario is worth vs the original PVsyst projection.

Performance Ratio — Adjusted PR as a percentage, scaled by the ratio of your adjusted generation to the PVsyst P50. Useful for benchmarking against contractual PR guarantees.

Specific Yield — Adjusted kWh/kWp/yr. Useful for comparing your scenario against industry benchmarks for similar locations and configurations.

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Step 5 — Read the Four Analysis Panels

Below the loss controls, four panels give you progressively deeper analysis of the scenario you’ve built.

Energy Loss Waterfall — A cascading bar chart running from Nominal STC energy (294.92 GWh) down to your adjusted E_Grid. Each bar represents one loss. Red bars are losses worse than the PVsyst design assumption, green bars are improvements, and peach bars are unchanged. The height of each bar shows exactly how many GWh that loss is consuming.

Loss Sensitivity Ranking — All 16 losses ranked by how many GWh and ₹ Crore you lose for every +1 percentage point increase. Temperature loss and IAM are almost always the top two on Indian plants. Parameters you have modified from PVsyst values are marked with a dot so you can see at a glance which levers you’ve pulled.

Monthly Generation Table — A side-by-side comparison of PVsyst baseline vs your adjusted scenario for all 12 months. Columns show GlobInc (kWh/m²), PVsyst E_Grid (GWh), Adjusted E_Grid (GWh), delta GWh, baseline revenue (₹ Crore), adjusted revenue (₹ Crore), and revenue delta. The annual total row at the bottom shows the full-year summary. The table scrolls horizontally on narrow screens.

25-Year Revenue Projection — A dual-axis chart showing annual revenue bars in ₹ Crore/yr alongside cumulative revenue lines, for both the PVsyst baseline and your adjusted scenario. The gap between the two cumulative lines at year 25 is the headline lifetime value difference — the single most powerful number for lender negotiations or O&M investment decisions.

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Step 6 — Export Your Scenario

When you’ve built a scenario you want to share or include in a report, click ⬇ Export CSV. The downloaded file contains every input parameter, the adjusted vs baseline comparison for all 16 losses, monthly generation data for all 12 months, and key summary metrics including annual and lifetime revenue.

Use ↺ Reset to PVsyst at any time to snap all sliders back to the original parsed values from your report — without needing to re-upload the PDF.

To run a different project, click ↑ New Report in the project ribbon and upload a new PDF. All sliders reset to the new report’s values automatically.

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Who Should Use This Tool

Design Optimisation — Compare soiling assumptions, tilt angles, and DC:AC ratios across design variants. See which loss reduction has the best GWh-per-rupee impact before committing to equipment or layout changes.

Lender Negotiations — Run the P90 scenario with conservative soiling, higher unavailability, and realistic curtailment. Show the lender a quantified worst-case with exact GWh and ₹ Crore numbers attached to every assumption — not just a narrative.

O&M Benchmarking — Enter actual observed losses (soiling from drone inspection, measured availability from SCADA) and see immediately how many GWh and ₹ Crore are being lost vs the PVsyst design assumption. Prioritise your maintenance budget using the sensitivity ranking.

Independent Technical Review — As an IEEA or technical advisor, stress-test the developer’s PVsyst assumptions. Adjust temperature coefficients, availability, and grid curtailment to produce a P90 view for inclusion in the lender’s technical report.

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The Three Losses That Matter Most

The sensitivity ranking will vary by project, but across most Indian utility-scale plants, the same three losses dominate.

1. Temperature Loss (typically 5–9%)

The largest single loss on any Indian plant. Modules running at 50–65°C lose 5–9% of their rated output. This is largely fixed by physics — you cannot reduce it much through O&M — but it is critical to model accurately. A 1% error in the temperature loss assumption on a 125MW plant equals 2.5 GWh/yr and ₹8 Crore over 25 years at a ₹3.20/kWh tariff.

2. Soiling Loss (typically 1–4%)

Soiling is the most actionable loss on most plants — it responds directly to your cleaning schedule. A poorly managed plant in a dusty corridor can run at 3–4% soiling loss vs a well-managed 1%. On a 125MW plant, that 2% difference equals 5 GWh/yr and ₹16 Crore over 25 years. This is why soiling frequency optimisation is consistently the highest-ROI O&M activity at most sites in India.

3. System Unavailability (typically 0.5–3%)

Unavailability captures inverter downtime, grid outages, planned maintenance windows, and forced outages. The PVsyst default of 1% equals 3.65 days per year of full outage. Poor contractual availability guarantees or chronic grid instability can push this to 2–3%, costing 2.5–7.5 GWh/yr. When reviewing IEEA reports, scrutinise the availability assumption carefully — it is applied at the very end of the loss cascade, when all the remaining energy is at its highest value, making every percentage point especially expensive.

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Frequently Asked Questions

What if my PDF doesn’t parse correctly? The parsing log shows you exactly which values were extracted and which fell back to defaults. You can manually adjust any slider after upload, so a partial parse is still useful — just verify the pre-loaded values against your report before running scenarios.

How is the adjusted generation calculated? The tool uses a sequential multiplicative loss model — the same approach PVsyst uses internally. Starting from Nominal STC energy, each loss is applied in cascade. The ratio of adjusted loss factors to baseline loss factors is then applied to your chosen P50/P75/P90 figure to produce the adjusted E_Grid.

Disclaimer:
Any information or data shared by users on this website/platform is done at their own risk. We are not responsible for any loss, misuse, unauthorized access, or disclosure of such data, including actions by third parties or security breaches beyond our control. Users are advised not to share sensitive or confidential information. This tool is built using the Claude AI.

Can I use this for a non-Indian project with a different currency? Yes. The tariff input accepts any value — simply enter your local tariff in your local currency per kWh. The ₹ Crore labels are cosmetic and do not affect the underlying calculation. A future version will include a currency selector.

Does this replace PVsyst? No — and it shouldn’t. PVsyst is the industry-standard simulation engine for full optical, thermal, and electrical modelling. This tool is designed for post-simulation analysis: auditing the loss assumptions in an existing report, running sensitivity analysis, and building what-if scenarios for negotiation or review. Think of it as a layer on top of your PVsyst output, not a replacement for it.

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Tags: PVsyst · Solar Design · Energy Yield · Loss Analysis · O&M · Lender Technical · IEEA · Bifacial · Tamil Nadu · Utility Scale