regulations is calculated. For panels lighter than this required minimum ballast will be
required to bring the weight up to the minimum required
The ballasting formula and a full explanation is available in the regulations.
It is important to know the approximate power output of your panel so you can arrange
any ballast required before the event, as you are required to provide your own ballast.
To obtain the approximate panel power either check its power output from the label
(probably this will be within 10% of the power that will be measured on the light box at
the event) or if it has no label measure its power output.
NOTE:
If you cannot measure your panel’s power output an approximation can be
obtained by measuring Open Circuit Voltage (OCV) and Short Circuit Current (amps)
(ISC) in full Sun, then by multiplying these together and multiplying the answer by the
cells fill factor (FF)
That is Approx. Power in Watts = OCV x ISC x FF
If the fill factor for your panel is unknown (probably the case) use 0.75 as the expected
fill factor for a good quality panel.
For stability, any ballast required is best secured as low down in the car as possible. Be
VERY careful and secure ballast properly. The forces acting when a car stops suddenly
from high speed (for example a crash) can be extremely high. Loose ballast flying around
inside your car can damage other components.
C: Fill Factor (Sometimes called Form Factor)
What is Fill Factor you ask? It is the panels actual power output divided by the product
of open circuit volts and short circuit current. (You may like to consider fill factor as a
sort of guide to panel efficiency or quality.)
See appendix F Photovoltaic cells and panel power testing page 71 for an explanation of
fill factor.
D: Panel Quality
Over the past few years at scrutineering at both the State and National events I have
noticed cracked cells in some panels refer to Appendix Q for more details.
4 Chassis
The chassis should be as light as possible but must be strong enough to hold together
during handling and running. It must also be stiff enough to hold everything in alignment
and position (consider the possibility of rough handling & accidents).
Take care that your chassis is not so stiff that the car tends to lift the drive wheel off the
track as the car moves over undulations in the track. We have observed this on several
occasions. Some form of suspension, or packing the drive wheel down lower than the
other wheels may be required.