Quick Answer
The load calculation formula in off-grid systems can be broken down into the peak load (in watts), the total daily energy (in watt-hours), and the total monthly energy (in kilowatt-hours) using the following steps: 1) calculate the peak load from a load profile or energy audit, 2) calculate the daily energy by multiplying the peak load by the number of hours of use per day, and 3) calculate the monthly energy by multiplying the daily energy by the number of days in the month.
Understanding the Load Profile
To accurately calculate the load for an off-grid solar system, it’s essential to understand the load profile. This involves identifying the peak load and the average load for different time periods throughout the day. For example, a household with a refrigerator, lights, and a TV may have a peak load of 2,000 watts during the evening hours, but the average load might be around 500 watts. A load profile can be created using a worksheet or software, such as PV Watts Plus or Helioscope, to help determine the peak load and average load for each time period.
Calculating Daily and Monthly Energy
Once the peak load and average load have been determined, it’s possible to calculate the daily and monthly energy requirements. To do this, multiply the peak load by the number of hours of use per day. For example, if the peak load is 2,000 watts and the household uses power for 8 hours per day, the daily energy requirement would be 16,000 watt-hours (2,000 watts x 8 hours). To calculate the monthly energy, multiply the daily energy by the number of days in the month. For example, if the daily energy requirement is 16,000 watt-hours and the month has 30 days, the monthly energy requirement would be 480,000 watt-hours (16,000 watt-hours x 30 days).
Find more answers
Browse the full Q&A library by topic, or jump back to the topic this question belongs to.