Solar Water Heating System Design Calculator
Professional Engineering Calculation & Report Generator
Flat plate collector systems | Demand → thermal load → collector area → storage → flow → pipe → pump → backup heating
1 Project Information
2 Hot Water Demand Calculation
| Fixture Type | Quantity | Demand Per Fixture (L/day) | Total Demand (L/day) | Remove |
|---|---|---|---|---|
| Grand Total Hot Water Demand | 0.00 | LPD | ||
HOT WATER DEMAND RESULT
Calculation methodDirect Capacity Method
Final design hot water demand5,000.00 LPD
3 Design Temperature Parameters
TEMPERATURE RISE
ΔT = Hot water temp − Cold water temp60 − 25
Design temperature rise35.00 °C
4 Thermal Energy Calculation
Q = m × Cp × ΔT
Mass of water, m5,000.00 kg/day
Substitution5000 × 4.186 × 35
Thermal energy required732,550 kJ/day
Thermal energy required203.49 kWh/day
Energy conversion: 1 kWh = 3600 kJ. Thermal energy is the daily heat input required to raise the full design demand from cold water temperature to the required hot water temperature.
5 Solar Design Parameters
OVERALL SYSTEM EFFICIENCY
ηcoll × ηsys × (1 − piping loss)0.50 × 0.90 × 0.95
Overall system efficiency42.75 %
Useful solar energy per m²2.1375 kWh/m²/day
6 Solar Collector Selection
The custom collector efficiency entered here overrides the collector efficiency in Section 5, and the custom area is used for the collector quantity calculation.
SELECTED COLLECTOR
ManufacturerVersoSun
ModelFP2.5Cu/Al
Collector typeFlat Plate Collector
Collector area per unit2.50 m²
7 Solar Collector Sizing
COLLECTOR AREA
Useful solar energy per m²2.1375 kWh/m²/day
Required collector area95.20 m²
Design margin area14.28 m²
Recommended collector area109.48 m²
COLLECTOR QUANTITY
Calculation109.48 ÷ 2.50
Number of collectors (rounded up)44 Nos
Actual installed collector area110.00 m²
Excess collector area0.52 m²
Design adequacy check✓ DESIGN ADEQUATE
8 Storage Tank Sizing
STORAGE CAPACITY
Substitution5000 × 1.2
Required storage capacity6,000 Litres
Suggested tank combination2 × 3000 L
Alternative combinations3 × 2000 L
Installed storage volume6,000 Litres
9 Solar Circulation Flow
CIRCULATION FLOW RATE
Substitution109.48 × 50
Solar circulation flow5,474 L/hr
Flow rate5.474 m³/hr
Flow rate91.23 L/min
Flow is based on the recommended collector area so that the circuit remains correctly balanced if the installed collector quantity is increased.
10 Preliminary Pipe Sizing
PIPE SIZE
Flow rate0.001521 m³/s
Pipe cross-sectional area0.0012675 m²
Calculated internal diameter40.18 mm
Recommended nominal bore50 NB
Pipe size is preliminary and final selection shall be verified based on actual pipe material, internal diameter, pressure drop, pipe length and hydraulic losses.
11 Pump Duty Calculation
RECOMMENDED PUMP DUTY
Total dynamic head16.00 m
Pump duty5.474 m³/hr @ 16.00 m head
For a closed-loop solar circulation system, static head is generally balanced between the supply and return circuits and is therefore not included in the pump head calculation.
12 Backup Heating Calculation
BACKUP HEATING
Base capacity50.87 kW
Recommended capacity58.50 kW
Suggested staging2 × 30 kW
Electrical input—
13 Equipment Schedule
| Sl. No. | Equipment | Model / Description | Capacity | Quantity | Unit | Remarks |
|---|
14 Design Summary
All calculations update automatically as you edit any input. Generate the report to view the full step-by-step calculation before printing.