Arduino current sensors


#1

Hello,

I am after please Arduino compatible current sensors for the following situations:

100W 12V solar panel
300W 12V wind turbine

Could you please recommend a sensor for each scenario?

I have no preference with regards to invasive or non-invasive.

Do I need 2 sensors for the solar panel and 3 for the wind turbine?

Many thanks,
Torsten.


#2

Measuring current of a solar panel does not get you much information, you also must measure voltage, to calculate power, which won’t be 100W most of the time.

However, choose one of the ACS current sensors based on the solar panel’s maximum current, which for a 12V 100W panel would be around 8.3A, but it is better to read the panel specifications, looking for Isc, the short circuit current. Assuming an Isc of about 12A, one of many suitable sensors would be

For a 300W 12V wind turbine, a nominal current may be 25A, but again you should read the wind turbine specifications to find the maximum current, or measure it under strong wind conditions. As it happens, the same sensor above would be enough.

I don’t see why you would need two sensors for the solar panel and three for the wind turbine. What gives you that idea? Just want to be sure we’re understanding.


#3

Thank you for your patience, James! Electronics is not my background and my understanding of electricity is limited. I am hoping that this little hobby install will help my understanding!

The solar panel reseller tells me that the 100W panel puts out 5.6 amps maximum.

I thought I may have needed a sensor for each wire, which is why I asked if I need 2 and 3 devices?

I presume that this device you have recommended does both AC and DC?

Does it also measure voltage? I guess the objective is to understand the power that is being generated by the solar panel and wind turbine.

So, I should order two of these?

Should I also get 4 x solderless ring terminal connectors?

This is a simple connection to my Arduino UNO?

Thanks James,

Torstein.


#4

Thanks for the additional information.

Current in a circuit is always the same, no matter where you look in that circuit. So if you imagine a battery torch, no matter where you measure the current, it should have the same numeric value. That’s why you only need one sensor to measure the current from a solar panel.

The current sensors in the ACS range don’t measure voltage. You’d need another way to measure voltage, if it was important to calculate power. It depends on why you want to measure, as well as what you want to measure. For me, current from a solar panel is often a good enough measure, especially when it is being fed into a battery that generally has the same voltage, give or take a little bit.

The current sensors in the ACS range are best for measuring DC, either stable DC or AC that varies by no more than 90 kHz (a limit of rate change that the sensor can report), but the Arduino has a limit on how often it can read the measurement. Solar panels generate DC, and it is very stable. Wind turbines generate either stable DC, or varying DC, it depends on how they are made, and what circuit is built into them.

Measuring AC is a different problem entirely, but from what you’ve described you don’t yet have any AC to measure. I’m randomly presuming you are planning to use a battery to store the energy.

The ring terminal connectors are useful if you have a crimping tool, or you can solder wires to the circuit board. You have to break one of the wires in the cable from the solar panel, and attach those wires to the large pads, such that the current generated by the panel has no choice but to flow through the black chip, the ACS715.

You’ll need to solder pin headers or wires to the three pads at the other side of the board so they can connect to the Arduino.

Hope that helps. I expect more questions. :grin: