Table of Contents
Understanding PV Array Sizing: A Comprehensive Guide
1. PV Array Sizing
PV array sizing is a crucial process for optimizing the performance of solar energy systems. It involves determining the correct number of solar panels required to meet specific energy needs. The right size ensures that the system can operate efficiently, generating sufficient energy without overloading or underutilizing resources.
The equation that may be used to size a stand-alone PV system is:
- WPV = peak wattage of the array, Wp
- E = daily energy requirement, Wh
- PSH: average daily number of Peak Sun Hours in the design month for the inclination and orientation of the PV array.
- ɳSys = total system efficiency.
The month the system is designed for is the month with the lowest average daily solar radiation during the system’s operational period. The number of peak hours is for the inclination and orientation of the PV array. If the only available information is for solar radiation in a horizontal plane, a tilt and orientation correction factor should be applied.
1.1 Wiring Solar Panels in a Series Circuit
Connect the positive terminal of the first solar panel to the negative terminal of the next one. Example: If you had 4 solar panels in a series and each was rated at 12 volts and 5 amps, the entire array would be 48 volts at 5 amps.
1.2 Wiring Solar Panels in a Parallel Circuit
Connect all the positive terminals of all the solar panels together, and all the negative terminals of all the panels together.
Example: If you had 4 solar panels in parallel and each was rated at 12 volts and 5 amps, the entire array would be 12 volts at 20 amps.
1.3 Rule of Thumb
You will require approximately 10m2 of surface for 1 kWp power.
2. Applicable Codes and Standards
- NEC Article 690 – Solar Photovoltaic Systems. Article 690 addresses safety standards for the installation of PV systems.
- Uniform Solar Energy Code – ICC
- Building Codes – ICC, ASCE 7-05
- UL Standard 1703, Flat-plate Photovoltaic Modules and Panels
- IEEE 1547, Standard for Interconnecting Distributed Resources with Electric Power Systems
- UL Standard 1741, Standard for Inverters, Converters, Controllers and Interconnection System Equipment for Use with Distributed Energy Resources PV Systems and the NEC
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References:
A. Bhatia, Course No: R08-002, https://www.cedengineering.com