BECO Electrical Safety & Energy Engineering

BECO Diagnostic EngineBS 7671 & CEB Standard

Solar Generation & MPPT Inverter Yield

Net Plus Export Tariff

LKR 23.11 / kWh

1. Select Inverter Target Capacity (AC)

2. Panel Cell Technology

Module Power Rating (Wp)

Spec: Vmp ~45.6V | Voc ~54.8V

Installed Modules4.96 kWp DC

8 Panels

DC/AC Ratio: 0.99x

Irradiance Region

Calculated with 55°C roof thermal derating.

Expected Monthly Generation

579 – 632kWh / mo

~19.3 to 21.1 units / day

Net Plus Monthly Export

LKR 14,005

~LKR 168,060 / year (Aug '26 rates)

Inverter MPPT String Architecture

1 String of 8 Panels

Min Startup: 90VSweet Spot: 360VMax MPPT: 520V

String Voltage (Vmp)

365 V DC

Max Open Circuit (Voc)

460 V

Efficiency Status

Peak MPPT Efficiency (Optimized around 360V)

* Modeled for Sri Lankan roof orientations with CEB/LECO August 2026 Net Plus tariffs. Bifacial calculations assume standard light-colored roof or slab mounting with an 8% reflective albedo bonus.

BS 7671 COMPLIANCE

Earthing System Architectures

Understand the fundamental grid earthing arrangements supplied by the CEB and how they dictate your property's safety engineering.

TT (Terra-Terra)

The utility provides only the Live and Neutral conductors. The consumer must provide their own connection to earth via a dedicated earth electrode (rod) driven into the local soil. Relies entirely on RCDs for fault protection.

BS 7671 Max Ze Limit

200.00 Ω

BECO Audit Target

< 21.00 Ω (Optimal for Type 2 SPD)

Main Bonding Size

10.0 mm² Copper (BS 7671 Standard)

Sri Lankan Network Context

The default and most common earthing arrangement supplied by the Ceylon Electricity Board (CEB) for domestic overhead residential networks.

Fault Path Equipment Chain

CEB Transformer

→

Overhead Live/Neutral

→

Cut-out / Meter

→

Consumer Earth Rod (Copper/Galvanized)

→

Main Earthing Terminal (MET)

⚠️

Critical Hazard Profile

High soil resistivity during dry seasons in Sri Lanka can cause TT earth loop impedance (Ze) to spike, rendering MCBs useless for earth faults. RCDs are mandatory.

CEB METERING

Sprint 350 Net Meter Guide

Learn how to read your official CEB Net Meter, verify your maximum demand, and check your load balance.

081830

Q1, Q2, Q3, Q4

8888888.888kW kWh kVA kVAR V A Hz

SECURE SPRINT 3503 Phase 4 Wire

1 / 19

System Identity

Lamp Diagnostic Test

Code: 081830Quadrants: Q1, Q2, Q3, Q4

Engineering Interpretation

Diagnostic test: All LCD display segments, decimal points, and quadrant icons illuminate simultaneously.

ENGINEERING BASICS

Electrical Fundamentals

Calculate real vs. apparent power for your facility, or run standard Ohm's law checks for circuit sizing.

Real Power (kW)

50 kW

Actual work-producing power

Power Factor (PF)

0.85

Efficiency ratio (kW / kVA)

⚠️ PF below 0.90 will incur CEB reactive power penalties. Capacitor banks required.

Apparent Power

58.82 kVA

Total demanded from utility

Reactive Power

30.99 kVAR

Wasted magnetic/inductive power

Engineering Validation

Apparent Power (kVA) Formula:kW ÷ PF

Calculation:50 ÷ 0.85 = 58.82 kVA

Reactive Power (kVAR) Formula:√(kVA² - kW²)

Calculation:√(58.82² - 50²) = 30.99 kVAR

HVAC ECONOMICS

AC Efficiency Cost Calculator

Calculate the real monthly running cost of your air conditioner based on its exact Input Power and daily usage.

1. Air Conditioner Capacity

2. Input Power & Efficiency

Rated Input Power (Watts)

Find this on your AC's manufacturer sticker (e.g., 1040).

Calculated EER

11.51

Standard Efficiency (Entry Inverter)

3. Daily Usage

8 Hrs/Day

1 Hr24 Hrs

Continuous Draw

1.04 kW

Monthly Consumption

250.32 kWh

Estimated Monthly Running Cost

LKR 25,032

Calculated at CEB Flat RateLKR 100 / kWh

LOAD PROFILING

ToU Load Visualizer

Map your monthly consumption across the three Time-of-Use periods to visualize your 24-hour continuous power draw.

Total Monthly Draw

Grid Consumption Output

600 kWh

100 kWh5000 kWh

Consumption Pattern

Total: 100%

Off-Peak20%

Day30%

Peak50%

24-Hour Power Profile

Continuous Grid Draw (kW) - Smoothed Load Curve

2.88 Max kW

~0.57 kW

~0.46 kW

~2.5 kW

00:0005:3018:3022:30

Energy Distribution

Daily Volume (kWh)

20 Total Daily kWh

Off-Peak

Day

Peak

Time-of-Use Financial Impact

Off-Peak CostLKR 3,960

Day CostLKR 8,460

Peak CostLKR 31,800

Total Estimated Monthly Bill

LKR 47,888

Fixed Charge & Taxes Included600 kWh Total

BS 7671 ENGINEERING

Cable Sizing Calculator

Verify your conductor cross-sectional area against strict Current Capacity (Iz) and Voltage Drop (Vd) limits.

Circuit Topology

Electrical Phase

Circuit Application

Installation Reference Method

Design Current ($I_b$)

20 A

Cable Length ($L$)

25 m

Select Copper Conductor Size

Current CapacityPASS

27A

Cable rating ($I_z$) must be ≥ 20A demand.

Voltage DropPASS

3.91%

Drop is 9V. Must be ≤ 11.5V (5%).

BS 7671 System Status

Compliant Architecture

✅

HVAC ENGINEERING

AC Sizing Plotter

Calculate the exact cooling capacity required for your room based on dimensions and sun exposure.

Room Dimensions

Length

12 ft

Width

10 ft

Sun Exposure & Insulation

Room Floor Plan

Aspect Ratio Visualizer

120 sq ft

(11.15 m²)

12 ft

10 ft

6,160 BTU

Required Cooling Capacity

6,160 BTU/h

Recommended AC Size:9,000 BTU/h
0.75 Ton

SOLAR AUDIT & SIZING

12-Month Solar & Grid Tracker

Visualize your year-round solar export vs. grid consumption to identify how much power you are leaking back to CEB at discounted tariffs.

Annual Grid Import

10340 kWh

Cost: LKR 517,000

Annual Solar Export

8220 kWh

Credit: LKR 221,940

Net Grid Balance

+2120 kWh

Offset Ratio: 79.5%

Net Annual Energy Bill

LKR 295,060

Payable to CEB

12-Month Energy Flow (Import vs. Export)

Solar generation exported to CEB vs. continuous grid energy drawn

Import (kWh)Export (kWh)

JanFebMarAprMayJunJulAugSepOctNovDec

Inspect & Tune: Jan

Adjust to reflect your actual utility bill readings

Month 1 of 12

Grid Import (kWh)820 kWh

Solar Export (kWh)650 kWh

Jan Net Grid Position:Net Deficit: +170 kWh

BESS Arbitrage Opportunity

Stop exporting power at LKR 27 to buy it back at LKR 50.

Over 12 months, you export 8220 kWh to the grid while buying back 10340 kWh. Integrating a BYD Battery Energy Storage System (BESS) captures solar during the day to power your home during expensive evening peak hours.

Tariff Delta Spread

LKR 23 / kWh

Avg Daily Storage Target

22.5 kWh / Day

Quattro Microgrid Power Flow

Dynamic topology, frequency shifting & load shedding

Grid Input

0V (Offline)

Solar Yield

2.8 kW

BESS Status

65% (-0.4 kW)

AC Freq

50.20 Hz

Victron Quattro Inverter/Charger

Grid failed. Islanding mode active. BESS & MPPT powering Critical Loads. Fronius throttled via frequency shifting.