What is the monthly energy use of an off-grid installation with a 1HP pump operating 10% of the time and a 20W light operating 100% of the time?

What is the monthly energy use of an off-grid installation with a 1HP pump operating 10% of the time and a 20W light operating 100% of the time?

• A. 44kWh
• B. 55kWh
• C. 68kWh
• D. 80kWh

Answer: (C)

To determine the monthly energy use of the off-grid installation, we first need to calculate the energy consumption of both the 1HP pump and the 20W light over the course of a month. Start with the pump. A 1 horsepower (HP) pump is equivalent to approximately 746 watts. If the pump operates 10% of the time in a month, we can calculate its monthly energy use as follows: 1. Convert the percentage of operation to hours: - A month typically has about 720 hours (30 days x 24 hours). - 10% of 720 hours is 72 hours. 2. Calculate the energy consumed by the pump: - Energy (kWh) = Power (kW) x Time (h) - In this case, 746 watts = 0.746 kW, so: - Energy = 0.746 kW x 72 h = 53.712 kWh. Next, consider the 20W light that operates 100% of the time. The energy consumption calculation is straightforward because it runs continuously: 1. Energy consumed by the light over the month: - 20 watts = 0.02 kW. -

To determine the monthly energy use of the off-grid installation, we first need to calculate the energy consumption of both the 1HP pump and the 20W light over the course of a month.

Start with the pump. A 1 horsepower (HP) pump is equivalent to approximately 746 watts. If the pump operates 10% of the time in a month, we can calculate its monthly energy use as follows:

1. Convert the percentage of operation to hours:

• A month typically has about 720 hours (30 days x 24 hours).

• 10% of 720 hours is 72 hours.

2. Calculate the energy consumed by the pump:

• Energy (kWh) = Power (kW) x Time (h)

• In this case, 746 watts = 0.746 kW, so:

• Energy = 0.746 kW x 72 h = 53.712 kWh.

Next, consider the 20W light that operates 100% of the time. The energy consumption calculation is straightforward because it runs continuously:

1. Energy consumed by the light over the month:

• 20 watts = 0.02 kW.