Advanced Solar, Battery & Electrical Engineering Calculator
1. Battery Bank & Backup Time
This calculator determines how long your battery bank can power connected loads. The calculation is based on the total installed battery energy, the usable battery percentage, and the efficiency of the inverter/system.
Theory:
Total Battery Capacity (kWh) = Number of Batteries × Battery Capacity per Unit
Usable Energy = Total Capacity × Depth of Discharge × System Efficiency
Backup Time = Usable Energy ÷ Load Power
Example: Four 5kWh batteries provide 20kWh total storage. If DoD is 90% and efficiency is 90%, usable energy becomes 16.2kWh. A 5kW load will therefore run for approximately 3.24 hours.
2. C-Rate & Discharge Analyzer
C-rate indicates how fast a battery is charging or discharging relative to its total capacity. High C-rates increase battery stress, heat generation, and degradation.
Theory:
Battery Current = AC Load ÷ Battery Voltage
C-Rate = Battery Current ÷ Total Battery Capacity (Ah)
Example: A 5000W load on a 51.2V battery system draws approximately 97.6A. If the battery bank capacity is 400Ah, then the discharge rate is 0.24C.
3. PV Array Sizing
PV array sizing determines the recommended solar panel capacity needed to properly support an inverter system and expected daily energy generation.
Theory:
Recommended PV Size = Inverter Size × Oversizing Factor
Daily Energy Output = PV Size × Peak Sun Hours × Performance Ratio
Number of Panels = Total PV Wattage ÷ Panel Wattage
Oversizing helps compensate for weather losses, dust, cable losses, and real-world operating inefficiencies.
4. Voltage in Series & Parallel
In series circuits, voltage adds together while current remains constant. In parallel circuits, voltage remains constant across all branches.
Series Formula:
V(total) = V1 + V2 + V3 + ...
Parallel Formula:
V(total) = Same Voltage Across Branches
Example: Two 12V batteries connected in series produce 24V. The same batteries connected in parallel remain 12V.
5. Current in Series & Parallel
Current behaves opposite to voltage in electrical circuits. In series, current remains the same. In parallel, current from each branch combines together.
Series Formula:
I(total) = Same Current Through All Components
Parallel Formula:
I(total) = I1 + I2 + I3 + ...
6. Resistance in Series & Parallel
Resistance determines opposition to electrical current flow. In series, resistances add directly. In parallel, total resistance decreases.
Series Formula:
R(total) = R1 + R2 + R3 + ...
Parallel Formula:
1/R(total) = 1/R1 + 1/R2 + 1/R3 + ...
Parallel resistances always produce a total resistance smaller than the smallest resistor.
7. Ohm's Law & Power
Ohm’s Law is one of the most important electrical engineering principles. It defines the relationship between voltage, current, and resistance.
Formulas:
V = I × R
I = V ÷ R
R = V ÷ I
Power (P) = V × I
Example: A 220V system supplying 10A produces 2200W of power.
8. Voltage Drop Calculator
Voltage drop occurs when current flows through cables with resistance. Excessive voltage drop reduces equipment performance and increases heat losses.
Theory:
Voltage Drop = (2 × Current × Cable Length × Resistivity) ÷ Cable Size
Recommended design targets:
DC systems: below 3%
AC systems: below 5%
Longer cable lengths and smaller cable sizes increase voltage drop.
9. Energy Cost Estimator
This calculator estimates electricity consumption cost based on load power, operating hours, and utility tariff.
Formula:
Energy Consumption = Power × Operating Hours
Cost = Energy Consumption × Tariff Rate
Example: A 5kW load operating for 8 hours consumes 40kWh daily. At ₦120/kWh, the estimated daily cost becomes ₦4,800.