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Calculate Solar Energy Design

Calculate Solar Energy Design, it is very important to make necessary calculations for the Solar Energy Design before the very use of Solar Backup, as the batteries are the power source which stores the solar power on to them during the day and discharges the power during the nights. The system setup gets bulky depending on the

  • Number of hours power is required (additional batteries have to be included),
  • Number of hour sun light is available
  • Number of solar panels required to pump the power to these batteries
  • The appliances peak load requirement.

It’s a universally known fact DC has high current value hence your system design must consider in withstanding this current which is vital to charge the batteries.

To evaluate the setup component need some of the factors must be considered.

RULE-1 in Solar Energy Design  -- Inverter capacity

Inverter capacity decides the ability to handle the AC load, the rule is simple, if the load is less than 800 watts/hour a 12V DC run system would suffice the need.

In order to understand the capacity figure out the wattage of appliances that would run on a concurrent power usage.

Inverter Capacity to Run selected load in a Solar Energy Design
Typical Energy Demand Calculations


Appliance1 (TV) = 30 W

Appliance2 (5 Lights of 10W) = 5x10 W = 50 W

Appliance3 (Laptop) = 60 W

Applaince4 (3 fan of 40 W) = 3x40 = 120 W

Total power usage = sum of all appliance power consumption

= 30 W + 50 W + 60 W +120 W

= 260 watts

The major drawback in the 12V DC system is its ability to handle the power demand is limited, as additional inclusion of batteries in parallel will increase the DC current.

However for simpler load and longer hour power supply in lesser wattage this still can be used.

It must be noted for higher the watt hour (Power) consumption a higher inverter capacity should be used usually a 24V inverter setup, this would take care of higher loads

However the ability to supply power in hour duration would be limited depending on the usage. A 1600VA inverter would fit the purpose.

Should you be interested to select components and build your own setup - click here.

RULE-2 in Solar Energy/Power Design-- Energy utilization per day in watt hour

Different appliances are used for different purpose at different intervals of the day. The peak daily power consumption is calculated with their hours of operation and thus nailing down the watt hour per day requirement.




Peak power consumption in (watt)

Number of hour of operation (hour)

Total Power consumption by device (watt hour)





5 lights of 10 W




Laptop of 60 W




3 Fan of 40 W




Total power use per day =


For optimal system design its practice to design 50% more to capacity

= 1560 + 50% (1560)

= 2340

Should you be interested to select components and build your own setup - click here.

RULE-3 in Solar Energy/Power Design-- Number of days the power can be drawn from battery

A perfect solar backup system design must consider the fact that no two days are similar in obtaining the sun light, the seasons vary locally due to earth’s atmospheric behavior etc.

Hence it is vital to design the solar back up system to hold the backup charge in battery for minimum of 2 days to 5 days.

Power stored in an array of batteries / battery bank in a Solar Energy Design
Power stored in an array of batteries / battery bank

In other words based on the watt hour requirement per day, the battery capacity should have 2 to 5 times ability to store and supply power for optimal uninterrupted operations.

In practice the number of batteries those require to be included in the system would increase.

Thus Solar Energy Design plays a vital role in the Design stage before investment and operations.

Should you be interested to select components and build your own setup - click here.

RULE-4 in Solar Energy/Power Design -- Calculating battery power storage capacity

The initial steps provided to calculate the Solar Energy Design the minimum power required.

Now this power requires to be stored in the battery. The minimum power that should be available form a battery at any given point of time in accordance to the number of days we require power from battery without recharging them.

In our above example 2340 watt hour per day is the minimum required power that will be consumed.

Now number of days we expect the batteries to discharge this power without recharging = 3 days (let’s assume)

Hence we need 2340 watt hour x 3 days = 7020 wh

Power Storage or Availablity in a normal battery during Solar Energy Design
Power Storage or Availablity in a normal battery

It should be noted batteries should never be drained or discharge power less than 50% of their rated capacity, this will decrease the life of the battery and the charge holding capability.

Thus (7020 wh x (1/50%) = 14040 wh ) should be the minimum power that should be readily available from the battery to discharge.

Power = Voltage (x) Current

To calculate the battery capacity (Ampere Hour or AH). Inverter system can be of 12V/24V/48V depending on application use. In this case we assume 48V. Hence

Current = Power / Voltage = 14040 / 48 = 292.5 AH approximately 300 AH battery is required. Thus Solar Energy Design plays an important role in a solar setup to deliver optimally.

Conclusion: Build your own Solar Setup through the Solar Energy Design

After your learning here on Solar Energy Design, should you be interested to select components and build your own setup - click here.



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