PV Flashcards
Direct radiation generator
(Unshaded sunshine hours/# of sunshine hours per day) * direct radiation
Total radiation generator
Diffuse radiation + direct radiation
Radiation losses
global radiation - total radiation
IV curve
relationship between voltage and current
What are important points in the IV curve?
Short circuit current: I sc = I max, V =0
Open circuit current: V oc = V max, I = 0
Maximum power point Mpp = P max : Vmp & Imp
If pv cell is operated at Vmp & Imp, the maximum power is produced
Fill factor
measure of quality of solar cell
(ImpVmp)/(IscVoc)
Efficiency n
generated power / power of incident sunlight
Generator area
modules * module area
theoretical annual energy yield
generator area * global radiation
real annual energy yield
theoretical annual energy yield * efficiency
Power
I [A]*V [V]
–> from IV-curve
Azimuth Angle
angle between North and the sun (or moon)
How do you determine the global radiation?
diagram of azimuth angle and tilt angle
How do you do a shade analysis?
using the Solar Orbit Diagramm: azimuth & elevation angle
What is the elevation angle?
tan = opposite side (vertical)/adjacent side (horizontal)
How do you determine the share of your own consumption?
installed pv output/electricity consumption
How does a PV cell work?
- direct conversion of solar radiation into electricity
- using semi-conductor - materials
- semi conductors form space charge region: pn junction
- positive space charge region in p-region
- negative space charge region in n-region
- when load is connected, electrons start flowing
- electrons recombine with holes in p-region
- PV gives DC
What possibilities are there to increase the share of own consumption?
- Generation → Equip PV modules with a tracking system
- Consumption → Adjusting the consumption to the generation
- Battery storage → Increase storage capacity
Law of series
U total = summe U
I = I1 = I2 = I3
Law of parallels
U total = U1 = U2 = U3
I total = Summe I
