Continuation from the String Watt mode that PVBuddy offers in the previous page which relies on Wattage reading from inverter or MPPT Charge Controller values (either from inverter display or bluetooth app). String Amp and Module Amp checking modes are illustrated here. Both mode require use of a Digital DC Clamp meter.
String Amp check mode is used if you wish to get hands on at site and can detect current influencing potential faults such as poor cable connections, diode failures, issues affecting the entire string or array e.g. general dirtiness on the string of modules. It does not detect shading due to activation of the module built-in bypass diodes; this is easily detected by the String Watt check mode which does not need use of the clamp meter.
String Amp mode
The String Amp mode entails use of a digital clamp meter and allows checking of a specific string or array without need to power down any part of the system. Checking steps are depicted below:
.png)
Next, single module or single panel can be tested via Module Amp check mode as explained below.
Module Amp mode
.png)
The Module Amp check mode is ideal for individual module or panel testing. Once sensor is in same orientation or inclination as module under test, short the connectors (yes, single module is ok) and measure the short-circuited current with clamp meter to check the results. Great for module test on site that comes packed in a crate or to identify the problematic module!
In case you missed out on PVBuddy Mobile App
Learn more of the mobile app here or you can directly download app at google Playstore here.
Want to see PVBuddy in action?
See PVBuddy used in field conditions with Nate's DIY Solar in this 20min video below.
Frequently Asked Questions (FAQ)
Q1. How is the sensor powered?
It runs on any 5Vdc power source such as a power-bank, power source or from your mobile phone via an On-The-Go (OTG) adapter.
Q2. What types of system it can test?
Grid tied inverter, MPPT charge controller PV based on DC and hybrid inverter designs connected to common modules. We recommend hybrid inverter to switch to grid during test to read the actual solar module generated current ampere readings. Off-grid systems with batteries to run under constant load during test e.g. turn on air-conditioning, heater etc.
UPDATE: For micro-inverters, the String Watt mode can be used to validate the energy produced for that string of modules in same orientation. String Amp test mode will not be feasible due to alternating current produced by micro-inverters. Lastly String Module can be used once the micro-inverter is disconnected during single module testing.
Q3. Does it account for ambient temperature and changes during measurements?
We measure via ampere current. Thanks to physics or mother nature behavior within solar cells, our method is almost unaffected by temperature. Here's why: most modules or panels are crystalline silicon based. Their temperature coefficients are typically 0.05%/degC or less. What this means a temperature increase of 40 degC (e.g. from 25 degC to 65 degC) of a STC rated 10A module will experience a mere 0.2A increase in readings or 10.2A absolute value.