Energy consumption modelling - ADU-RES

esponse to the variable energy input and this is fully represented in the
modelling.
Selection of a 1-hour time-step facilitates simulation of a whole year of
operation so that seasonal and weather variations can be represented.
Variations occurring within an hour, such as passing clouds affecting the solar
input and wind turbulence, are not represented, but trial simulation runs using
shorter time-steps have shown no significant differences in overall results.
3.2 Input data
The real demonstration systems (on which the models are based) are located
in various countries, and naturally, their performance is very dependent on
local conditions:
• Solar radiation
• Wind speed
• Feed water concentration and temperature
• Ambient temperature
The software models use hourly data to represent these variables, and the
details of the data sources are given in the “assumed data” section for each
system.
3.3 Photovoltaics (PV)
Ambient temperature and solar radiation data is used to model cell
temperature using NOCT 8 . The operation of each PV cell is then represented
by a one or two-diode model, calibrated to match the manufacturer’s
published current-voltage (I-V) curves for the module.
The series-parallel configuration of the array is represented by simple
multiplication of currents and voltages. No allowance is made for mismatch
and shading losses; these losses should be small provided that good-quality
modules are installed in open aspect and kept clean.
3.4 Maximum power point tracking (MPPT)
The maximum power point is determined from the I-V curve mentioned above.
The model assumes that the tracking algorithm is perfect: no tracking errors.
Losses in the DC-DC or DC-AC power-electronic converter are modelled
appropriately.
8
Normal Operating Cell Temperature (NOCT), see Markvart, Tomas (1999), Solar Electricity.
Chichester, Wiley, page 88.
ADU–RES WP6 Deliverable 6.1 Page 12 of 69