ECN on-line yearly yield simulator: help

[ECN home page] --> [Solar Energy] --> [yearly yield simulator] --> [help]

ECN - Solar Energy offers this programme to provide a tool to the interested public for calculations of the estimated energy yield from grid-coupled PV systems. The programme uses:

1. meteorological data for the ambient temperature, the direct and the diffuse radiation in a horizontal plane for a specific location (De Bilt, Netherlands)
2. the Perez model (see: Duffie and Beckman, ISBN 0-471-51056-4, Solar Engineering of Thermal Processes, chapter 2.16) for the estimation of the radiation on a tilted surface
3. data for the PV module and the PV inverter

• the tilt angle of the PV modules (angle with the horizontal plane)
• orientation of the PV module (0=north, 90=east, 180=south)
• start and end month of the simulation period (12-1 means the months December and January)
• K-factor or the temperature factor, K=0.04 K/(W/m2) means that at an irradiation of 1000W/m2 the module temperature is 40 K above the ambient temperature. For free standing modules K=0.015, for roof integrated modules K=0.04.
• The loss factor represents possible decreases in the available DC power, e.g. due to dirt on PV modules or to mismatch effects, default equal to 1.
• The number of modules in the system. Can be specified as a decimal number to match the module power to the inverter power.

• Direct part of the irradiation on the PV module
• Diffuse part of the irradiation on the PV module
• Irradiation on the PV module by light reflected from the ground
• Total energy incident on the PV module in the selected part of the year.
• What remains of the energy after applying optical losses due to the fact that the irradiation does not impinge perpendicularly on the module.
• What remains of the energy after applying the conversion efficiency of the module.
• What remains of the energy after applying temperature influences on the conversion efficiency of the module.
• What remains of the energy after applying the user specified loss factor.
• What remains of the energy after the inverter conversion efficiency has been applied.
• What remains of the energy after inverter overload. The inverter can never deliver more than it's nominal power. The part of the energy balance can be used to assess whether the inverter is well dimensioned.
• Ratio of energy produced at AC side of inverter and product of total irradiation on module and STC efficiency of module.

F.D.J. Nieuwenhout
ECN - Solar Energy
PV Systemtechnology
E-mail : nieuwenhout@ecn.nl