PV Sensor: The meter uses a polycrystalline silicon PV cell as the sensor. The cell is
mounted on the top end of the meter, perpendicular to the display. The sensor responds to a
spectum bandwidth of approximately 0.3-1.1 microns. A generic spectrum for a silicon PV
cell show as below. The meter is intended for outdoor measurements of natural sunlight. The
PV sensor is located behind a plastic diffuser.
Meter Calibration: Meters are calibrated on clear days in natural sunlight and adjusted to a
reference cell periodically calibrated with pyranometers at Sandia National Laboratories.
Meters are pointed directly at the sun for calibration with the plastic protection cover in place.
Off-angle calibration is not done. However, empirical data indicate meter-to-meter
performance remains consistent up to 40 degrees off-angle from the direct normal. Beyond
40 degrees the readings start to diverge and may reach 10 - 15% when pointed 70-80 degrees
away from the sun. The meters are calibrated in groups and records for individual meters are
Care of your Meter: The meters are designed for use in the field but you should treat them
as you would your voltmeter; avoid dropping them, do not leave them out in the rain. They
are not sealed for continuous exposure to weather. The LCD display may darken if exposed
to direct sunlight for a prolonged period.
Meter Repair: We stand behind our products. If your meter is damaged or malfunctions,
contact Daystar for instructions about repair or return. A repair charge may may assessed if
your meter is more than one year old.
Using Your Meter:The Daystar solar meter measures instantaneous solar power and provides the reading
in Watts per square meter. You can calculate the total power striking the PV array by multiplying the area
of the active PV material by the reading from the meter. You can estimate the output power from the PV
array for that condition by multiplying by the advertised module efficiency. You would have to adjust that
value for losses, temperature effects, inverter efficiency, etc., to obtain the actual system output. More
information is available as a .pdf download here.