Photovoltaic Instrumentation

Photovoltaic instrumentation is a wide group of different measurement instruments used in photovoltaic systems. Most common are different panel meters, such as V-meters, A-meters, Ah- or kWh-meters. They could be produced as part of other devices like inverters or charge regulators or as standalone meters for wall mounting or with mounting clips for 35 mm DIN rail mounting. Ah-counters can be used for battery monitoring. Such instruments helps us to estimate how much battery capacity was used and how much could still be employed. Application of kWh-counters in grid connected systems calculate how much electricity was produced by the photovoltaic system and transferred to the public grid, and how much electricity was transferred from the public grid to households. More sophisticated measurement instruments used by professionals include PV array analysers, thermal cameras, solar radiation measurement instruments and solar simulators.

Panel Meters

A general recommendation for PV instrumentation design and application include: A careful A-meter design is required for use in PV systems. In PV systems large currents can occur, therefore, only suitable shunts should be used. Even if a proper shunt is applied, you should consider a cooling necessity. Always apply a suitable circuit breaker. Always apply a proper cable. Thin cable can cause unexpected loss or fire in case of large currents. Never use cheap panel meters or other equipment, which is not intended for application in DC/photovoltaic systems. How to build digital A-meter – some instructions A simple digital A-meter can be build by an advanced hobbyist. I have provided some general information and design rules. Most of DVA meters are based on ICL7106 or its low power derivates or successors. This is most commonly applied cirquit for DVM applications. However, there are some disadvantages to this circuit for application in PV systems. Separate GND and IN-LO signals are required. In most cases you cannot simply connect IN-LO and GND pin. Some precautions should be taken and some special design techniques should be applied. For details please see the links below. You can use any other similar ADC, but MAX131/MAX138 are preferred due to some advantages, such as low power consumption and included internal band-gap reference. The circuit could be used for: Photovoltaic systems monitoring Solar-powered instrumentation Battery-powered instrumentation Marine instrumentation Power supplies monitoring Energy management systems Portable instrumentation The advantages of the circuit are: Wide supply voltage range from 3V to 30V; for low voltage power supply low voltage OpAmps should be used, very low power supply current < 1mA, wide current sense range depending on a current shunt used, with ICL7660 as voltage converter, single supply is adequate. Similarly a digital V-meter can be constructed.

Panel Meters - Links

High Current Resistors

PV Array Measurement Equipment

Solar Simulators

Thermal Cameras & Imaging

Originally developed in building construction and industrial thermal analysis thermal cameras are nowadays very useful tool for detailed thermal inspections of solar arrays. With periodical inspections array problems (module hot spots) can be detected in advance so that large mailfunctions and yield (money) loss can be prevented right on time.

Sensors and Actuators

Additional Information - Books

Wagner, A. (1999), Photovoltaik Engineering; Springer.
Badescu, V. ed. (2008), Modeling Solar Radiation at the Earth Surface; Springer, ISBN 978-3-540-77454-9.
Sayigh, A.A.M., ed. (1977), Solar Energy Engineering; Academic Press, ISBN 0-12-620850-6.
Rösemann, R. (2004), Solar Radiation Measurement, From Sensor to Application; Gengenbach Messtechnik, ISBN 3-936947-70-8.
Hulstrom, R.L. ed. (1989), Solar Resources, Solar Heat Technologies: Fundamentals and Applications; MIT Press, Cambridge, MA, ISBN 0-262-08184-9.


WMO (2008), Guide to Meteorological Instruments and Methods of Observation; WMO-No. 8, Seventh edition, ISBN 978-92-63-10008-5.


Freire, R.C.S. et al. (1998), Dynamic Response of a feedback Thermorestive Electrical Substitution Pyranometer; Journal of Solar Energy Engineering, Volume 120, p.126-130.