A MUST HAVE FOR DIY OFF GRIDDERS

A long time ago the only way to measure an electrical current was to open a circuit and patch in an amp meter. That in itself was often times impractical and also dangerous on live circuits. Most multi meters were limited to a maximum of 10 A current.

So now, that we are dealing with string amperages of 10 Ampere and more, it is paramount for “Do It Yourself” folks installing or trouble shooting an off grid electrical system to own an Amp Clamp that can measure AC and DC current. It should be auto ranging and capable to read current sufficient to match your maximum Amp’s. Best to get clamp with a multi meter for AC and DC Voltage and resistance. Some Amp Clamps come with a temperature probe and can also measure your AC frequency.

These meters come in handy for a multitude of tasks. You will be able to test individual strings leading to a combiner box. You can truly check if a PV module is functioning properly. Just to measure the open circuit voltage is only half the story. You must have the module in unshaded sunlight and short circuit the leads and using the amp clamp check the current. If it is near the nameplate rating you can assume it should be okay. If the current reading is significantly less your module may have micro cracks or a bad bus bar. You can also determine the self consumption of your inverter by disconnecting / shutting off / all loads and charge equipment just have your inverter on standby. Multiply the measured current by the battery voltage. The results are the Watts of self consumption. Multiply by 24 hrs. to calculate the daily consumption. If measuring small currents, you can loop the conductor multiple times through the clamp. Each additional loop will increase the reading by one time the current. For example, if the current flowing through your conductor is 0.3 A looped 3 times in the clamp the reading will be 0.9 Amp.