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Solar System Sizing Tool

Solar System Sizing Tool

The following tool is intended to assist users to determine a size of an entry-level solar system for home use, which includes the solar panels, inverter, batteries and user load. Products listed and its information is that of The Sun Pays solar products. The tool utilizes product information such as efficiencies in order to give a more realistic solar system design.

Disclaimer: The tool is intended to be used as a guide. The Sun Pays can not be held responsible for the outcome of the results of the tool. It is still the end-user's responsibility to confirm if the selected equipment will be suitable for the user's needs or to obtain professional help from accredited installers.

Feedback: The tool is still a work in progress. At the current stage, the tool is only for 48V solar systems. For requests and feedback, please contact us.

How to use the tool:
Step 1: Choose the solar panel configuration. The panel configuration will be the panels in series and how many series arrays will there be in parallel.
Step 2: Choose the type of solar panels.
Step 3: Choose the battery type and configuration.
Step 4: Choose the inverter type.
Step 5: Fill in the user load. A list of common items is provided. Choose the number of hours the items in used in the day and night
Step 6: Review the feedback and make changes to the system setup if required.

Solar System Block Diagram

Step1: Solar Panel configuration:

Total number of panels =

Step 2: Type of panels used:

Step 3: Batteries and configuration:

Step 4: Inverter:

Step 5: Power usage:
The power usage is divided into the day time use for 6 hours (10AM to 4PM) of sunlight and the night time use for the remainder of 18 hours. The list below can be use to estimate the power consumption for day time and night time. Actual values will differ depending on appliance type and model.

Item Day (10am to 4pm) Nigh (4pm to 9am)
Tv (32") hrs hrs
Tv (40") hrs hrs
Tv (50") hrs hrs
Tv (65") hrs hrs
Decoder hrs hrs
Sound System hrs hrs
Play Station / X-box hrs hrs
Dishwasher cycles cycles
Microwave min min
Kettle cycles cycles
Fridge/Freezer (200L) quantity
Bar Fridge quantity
Ice Machine hrs hrs
Laptop hrs hrs
PC hrs hrs
Printer hrs hrs
Wi-Fi Router hrs hrs
Cell Phone Charger cycles cycles
Aircon 9000BTU (non-inverter) hrs hrs
Aircon 9000BTU (inverter type) hrs hrs
Aircon 12000BTU (non-inverter) hrs hrs
Aircon 12000BTU (inverter) hrs hrs
Aircon 16000BTU (non-inverter) hrs hrs
Aircon 16000BTU (inverter) hrs hrs
Washing Machine cycles cycles
Tumble Dryer cycles cycles
Hair Dryer min min
Hair Straightener min min
LED Bulb lights for hrs lights for hrs
CFL Bulb lights for hrs lights for hrs
Fluorescent Tube 4ft lights for hrs lights for hrs
Fluorescent Tube 5ft lights for hrs lights for hrs
Total: kW.h Total: kW.h

Step 6: Results
The solar system information is displayed below with feedback messages on potential issues. Changes can be made to the selected equipment above in order to comply with system requirements (such as Voc limits on inverter and battery capacity depending on load).

Result Message
Solar Array Info
Open Circuit Voltage:V
Maximum Power Voltage: V Upper Limit:
Lower Limit:
Maximum Power: W
Generated power during day: kW.h
Generated power available to charge battery: kW.h
Power available to supply day load: kW.h
Battery Information
Battery state of charge @ 4pm: %
Useable Capacity @ DoD: kW.h
Power required to recharge in 6 hours: W
Maximum Charge Current (set on inverter): A
Battery nominal voltage: V
Hours to drain battery at night: h
Inverter Information
Min PV voltage: V
Max PV voltage: V
Max PV oc voltage: V
Max PV array power: W
PV Charger efficiency: %
Utility supply information
Utility power required for day time load: kW.h
Utility power required for night time load: kW.h
Monthly cost for day time load make-up: R
Monthly cost for night time load make-up: R
Monthly cost for day time load if no solar is installed: R
Monthly cost for night time load if no solar is installed: R
Monthly savings: R
Annual savings: R
Annual CO2 emission reduction: kg


If you have any feedback or suggestions on the solar sizing tool, please submit it below: