Tech OVN

Calculator

Solar Self-Consumption Calculator

Pick your region and metering arrangement, plug in your plant + load + tariff, and see how much your rooftop solar is actually doing for you. Models net metering (the dominant arrangement for sub-500 kW C&I rooftop solar in India), net billing, and gross metering — plus a separate demand-charge avoidance pool that net metering doesn't address.

Inputs

Result

Self-consumption %
100%
Annual generation
124.8 MWh
Self-consumed
124.8 MWh
Exported to grid
0 kWh
Annual energy benefit (kWh × tariffs)
₹11.2 L
Self-consumed + exported credited at retail tariff (₹9.0/kWh)
Demand-charge avoidance opportunity (separate)
₹1.7 L/yr
Conservative ~7% MD reduction from real-time monitoring + load-shifting alongside solar generation. Net metering credits kWh, not kVA — this value is unlocked separately, by measurement.
Simple payback (energy only)
4.0yrs
Blended kWh value
₹9.00/kWh
Carbon offset: 89.9 tCO₂/yr (using 0.72 kgCO₂/kWh grid factor for INDIA)
Net-metering reality check: exported kWh is credited at retail tariff (no tariff gap). The hidden losses are demand charges (above), banking caps, ToU arbitrage, plant under-performance, and CBAM Scope 2 audit gaps — none of which net metering addresses. Behind-the-meter measurement is what surfaces them.

How this works

The calculator models a simplified annual energy balance with two value pools — kWh-side benefit (which depends on your metering arrangement) and kVA-side demand-charge avoidance (which is independent of metering and only unlocked by measurement).

Annual generation = Plant size (kWp) × Specific yield × Performance ratio
Daytime load = Annual load × Daytime load share
Self-consumed = MIN(Generation, Daytime load)
Exported = Generation − Self-consumed

Net metering: all generation credited at retail tariff (1:1)
Net billing: Self-consumed × Grid tariff + Exported × Feed-in tariff
Gross metering: All generation × Feed-in tariff (load billed separately)

Demand-charge avoidance ≈ Contract demand × Demand charge × 12 × ~7%
Simple payback = Plant cost / Annual energy benefit

The 7% demand-reduction figure is a conservative real-world estimate from real-time monitoring + load-shifting alongside solar generation. Actual savings depend on how aggressively your operations team uses the visibility. Real self-consumption depends on hourly matching — for accurate measurement, you need behind-the-meter hardware on three measurement points (generation, consumption, grid). That's what Tech OVN's solar monitoring system does.

Typical self-consumption ratios by facility type

Indicative ranges — actual ratios vary by plant sizing, load profile, and weather. The lower number assumes plant is over-sized for daytime load; the higher number assumes good sizing match.

Facility typeTypical self-consumptionWhy
Hotel / hospitality70–90%24/7 load profile absorbs almost all daytime generation
Hospital75–95%Continuous critical load + HVAC during the day
Manufacturing (single shift)60–80%Daytime production aligns with solar generation hours
Manufacturing (multi-shift)75–90%Larger continuous load absorbs daytime generation
Commercial office50–75%Weekday-only daytime load; weekend export losses
Data centre60–80%Continuous load but typically over-sized solar plant
Warehouse / logistics30–55%Limited daytime electrical load relative to roof area
Cold storage70–85%Continuous compressor load matches generation

Net metering masks the real losses

For sub-500 kW C&I rooftop solar in India under net metering, exported kWh is credited at the retail tariff. There is no export-vs-self-consume tariff gap — but that does not mean your plant is delivering full value. The losses simply move elsewhere.

  • • Maximum demand penalties: net metering credits kWh, not kVA. If your peak occurs in non-solar hours, you still pay full demand charges.
  • • Banking caps and forfeit: most states cap banking at 90-100% of consumption. Over-sized plants forfeit excess silently.
  • • ToU / TOD tariff arbitrage lost: net metering settles at retail; ToU spreads (in MH, KA, AP, TN) make evening 2-3x off-peak. Solar offsets daytime peak only.
  • • Plant under-performance hidden: net credits keep the bill looking fine even when the plant is producing 70% of expected. PR drift goes unnoticed for years.
  • • Banking settlement leak: excess banked units settled quarterly or annually at the feed-in rate (lower than retail), not 1:1.
  • • CBAM Scope 2 audit failure: EU regulators want kWh-level attribution per unit of product. Net metering accounting credits don't satisfy CBAM verifiers.
  • • BESS sizing impossible: battery capacity needs hourly grid-vs-solar data, regardless of metering arrangement.

All seven require the same fix: behind-the-meter measurement of generation, consumption, and grid flow. The Tech OVN solar monitoring system measures all three with Class 0.5S meters.

From estimate to measurement

This calculator gives you a back-of-envelope view. The next step — when you're sizing a plant, validating EPC claims, sizing a BESS, or reporting ESG carbon offsets — is hardware measurement on the three points that matter: solar generation, site consumption, and grid import/export. Tech OVN's solar monitoring system does exactly that, with Class 0.5S meters and a multi-site cloud dashboard.

Solar PV Monitoring System (Behind-the-Meter) →Industrial Energy Monitoring System →Energy Audit ROI Calculator →

Frequently Asked Questions

Common questions about net metering, self-consumption %, demand charges, and how to actually unlock value on net-metered solar.

Solar self-consumption % is the share of solar generation consumed on-site rather than exported to the grid. It is one of the most useful diagnostic numbers for a rooftop solar plant, but its financial meaning depends on which metering arrangement applies — net metering, net billing, or gross metering. Under net metering (the dominant arrangement for sub-500 kW C&I rooftop solar in India), exported solar is credited 1:1 at the retail tariff, so the export-vs-self-consume tariff gap is small or zero.
Net metering: exported kWh is credited 1:1 at the retail tariff against future imports — typical for residential and most C&I rooftop solar in India below the state-specific cap (commonly 500 kW). Net billing: exports are paid at a separate, lower feed-in tariff; consumption from the grid is billed at the retail tariff — increasingly common for plants above the net-metering cap. Gross metering: all generation is exported at a fixed feed-in tariff and the facility's load is billed entirely from the grid at retail tariff. Confirm which arrangement your DISCOM applies to your sanctioned solar capacity before sizing or reading this calculator's numbers.
Because net metering credits kWh, not kVA, and not time. Even under perfect 1:1 net metering, you are still bleeding value in five specific ways that net metering does not address: (1) maximum demand penalties on your kVA peak, often during non-solar hours, (2) banking caps and forfeit when generation exceeds the state-allowed limit, (3) ToU / TOD tariff arbitrage if your retail tariff is time-differentiated, (4) plant under-performance hidden by net credits — soiling, inverter derating, string faults that the bill alone cannot reveal, and (5) CBAM and ESG Scope 2 audits that demand kWh-level attribution rather than monthly net credits. Self-consumption % is the diagnostic — measurement is what unlocks the value.
It compares annual generation (plant size × specific yield × performance ratio) against the daytime portion of facility load (annual load × daytime load share). Self-consumed = the smaller of the two; the rest is exported. This is a simplified annual model — real self-consumption depends on hour-by-hour matching of generation with load. For accurate measurement, the only path is hardware-grade behind-the-meter monitoring at three points (generation, load, grid).
Specific yield is annual energy generated per kWp installed (kWh/kWp/year). It varies by location: India 1500-1700, UAE / Middle East 1800-2000, Africa 1700-1900, Europe 900-1300, USA 1300-1700, Southeast Asia 1400-1600. Your EPC contractor's commissioning report or the inverter's first-year data is the source of truth. We default to regional averages when you pick a region.
PR is actual energy delivered as a % of theoretical maximum. Losses include inverter conversion (~3-5%), DC cabling (~2-3%), AC cabling (~1-2%), soiling (~3-7% depending on cleaning frequency), shading, and module degradation. Typical PR for a well-designed plant is 75-82%. Below 70% suggests something is wrong (heavy soiling, undersized inverter, partial shading, faulty strings) — exactly what continuous monitoring catches. Under net metering, PR drift is invisible to the owner because the bill keeps looking fine.
Net metering credits kWh, not kVA demand. Most C&I tariffs in India (and globally) include a maximum demand charge billed monthly per kVA of recorded peak — independent of how many kWh you consumed. If your peak occurs in a non-solar hour (typical evening peak), solar generation does not reduce that charge. Real-time measurement plus deliberate load-shifting (HVAC pre-cooling, deferrable processes, EV charging in solar hours) typically reduces recorded MD by 5-10%. This is a separate value pool from the kWh side and is often where the largest savings hide on net-metered plants.
Three levers: (1) shift discretionary loads (HVAC pre-cooling, water heating, EV charging, pumping, batch processing) into solar generation hours, (2) right-size the plant to match daytime load — over-sizing pushes excess into export, (3) add behind-the-meter battery storage to absorb excess generation for evening use. Increasing self-consumption matters more under net billing or gross metering than net metering, but even under net metering it reduces banking-cap risk and improves demand-charge alignment.
It works for any plant size, but the buyer profile we serve is commercial and industrial rooftop solar — typically 50 kWp to 5 MWp. Residential solar follows the same math but with much smaller numbers. Utility-scale solar plants are designed primarily for export, so the self-consumption framing doesn't apply.