APPENDIX N. SOLAR PANEL POWER SUPPLY
Introduction
The SP32, solar panel kit is intended to permit the PQ100 to run for extended or, indefinite
periods of time depending on the available sunlight (solar radiation) at a given location. The
solar panel may only be used as the sole source of power for a U.S. EPA-designated
instrument if sampling is not being performed every day (i.e., continuously).
Because of the low current draw of the instruments they are highly amenable to this
technique. Given sufficient sunlight, they may be deployed in locations where no line power
is available. The basic components of the solar kit are:
1. 32-watt solar panel with mounting brackets.
2. Built in voltage regulator.
3. 100+ amp hour (approx.) ballast battery. (User supplied).
The purpose of the external high capacity battery is to provide back up power on days when
there is little or no sunlight. The recommended battery capacity will provide 7-8 days run
time with little or no sunlight. It will recharge, almost completely, after one days= use
during a day of full sunlight while the instrument is non-operational. Complete recharging of
a fully depleted system would require 10 days.
This type of system should not be considered for latitudes higher than 45-50Ε N or S, or
particularly overcast regions.
Operational Considerations
While the use of solar power is highly desirable from the standard of utilizing a renewable
energy source and being freed from the need to locate a source of power in difficult
situations, there are some preliminary considerations. Clearly, the PQ100 is not operating
directly from the received energy of the sun but rather from a battery, which has been
charged by that energy. If a PQ100 were to be run continuously from the internal and
(recommended) external battery, 7 to 8 days run time could be achieved. However,
considering only EPA designated sampling conditions, i.e. sampling from midnight to
midnight, then it would be possible to run on alternate days yielding one day to replenish the
energy used. Given that this is accomplished in full sunlight while the instrument is running,
the extra day recovery reduces the need for full sunlight by 50%. If the popular, one in 3
days, or one is 6 days schedule is utilized, the probability of complete replenishment is
greatly increased.
Experience has shown that on cloudless days in the Boston area, 5 Kwh/M
2
insolation will
replenish the energy used by a PQ100. In order to determine the suitability of the PQ100
solar system for a given location, Appendix A of the cited reference gives the insolation
index for 54 locations in the US and other places throughout the world. Given a one in 6 day
sampling schedule; only Fairbanks Alaska is unsuitable for solar application in the months
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