testing a solar panel

[anm]

I have acquired a second 100 watt poly Renogy solar panel and I want to test it before hooking it up with my first panel. I have measured the open circuit voltage put out by it and it's about 19.7 volts whereas Renogy list it as 22.4 volts in their specs. But I could accept that difference right now, since we are having scattered, high clouds.

My real question is this: I would like to measure the short-circuit current which the Renogy specs list as 5.82 amps, can I temporarily short the solar panel and not cause it any harm?

 

[Optimistic Paranoid]

I'm pretty sure that the published specs you are trying to check are based on measurements made in a controlled environment. The panels at a specified temperature, and a precise amount of light (confirmed by a calibrated light meter) and possibly a light source of specific wavelengths.

If you can't duplicate the conditions, I don't know how meaningful any measurements you get are going to be.

But by all means, try it and let us know.

Regards
John

 

[anm]

I'm pretty sure that the published specs you are trying to check are based on measurements made in a controlled environment. The panels at a specified temperature, and a precise amount of light (confirmed by a calibrated light meter) and possibly a light source of specific wavelengths.

If you can't duplicate the conditions, I don't know how meaningful any measurements you get are going to be.

But by all means, try it and let us know.

Regards
John

I was only wanting to test it so I could be sure it was working, the panel looked like someone had taken it apart. I wasn't wanting to see if it met the factory specs, just make sure open voltage was close and short-circuit amps also close. And testing it it does appear good...

 

[RogueRV2]

Hi ANM,

We do not even know how they created the ideal conditions to validate the panel output. We can measure it's performance against the other Renology panel that you have. Hook it up and compare!

 

[anm]

Hi ANM,

We do not even know how they created the ideal conditions to validate the panel output. We can measure it's performance against the other Renology panel that you have. Hook it up and compare!

I have done that. My intention was only to verify that it was working. I got over 20 volts open-circuit, and almost 4 amps short-circuit (still partially cloudy), which was in the ball park with the other solar panel I have.

---

And as to my original question: short-circuiting the panel (temporarily anyway) has done no harm...

 

[highdesertranger]

I would hook it up to a low battery and check with a clamp amp meter. I wouldn't do it by touching the 2 wires together. does our local zen master stern have a thoughts on this. highdesertranger

 

[RogueRV2]

If the panels are similar in performance when tested one after another then you likely have a two good panels!

 

[AlecEdgs]

I have acquired a second 100 watt poly Renogy solar panel and I want to test it before hooking it up with my first panel. I have measured the open circuit voltage put out by it and it's about 19.7 volts whereas Renogy list it as 22.4 volts in their specs. But I could accept that difference right now, since we are having scattered, high clouds.

My real question is this: I would like to measure the short-circuit current which the Renogy specs list as 5.82 amps, can I temporarily short the solar panel and not cause it any harm?

Hello friend I have got new panel.. I do want to test its output.. Can you tell the right way to do it?

 

[anm]

Hello friend I have got new panel.. I do want to test its output.. Can you tell the right way to do it?

I'm not sure of the 'right way', but what I did was this:
you will need a DVM (digital voltmeter) capable of measuring D.C. voltage and currents up to 10 amps, and a set of 'pig tails' for the MC4 connectors (Renogy includes these if you buy their starter kit). If you don't have the pig tails you will still be able to do it, it's just more awkward.

Set the panel facing the sun on a bright sunny day, connect the pigtails, set the meter to measure D.C. volts, plug the leads into the right jacks, and measure the D.C. voltage across the two pig tails. That gives you the 'open-circuit' voltage. The reading on the Renogy Poly 100 watt panel should be about 20 volts +- a little. Renogy specifies 22.4 volts.

Then switch the meter to the 10 amp scale, plug the leads into the correct jacks and again connect them across the pig tails. The shunt inside the meter will short-circuit the solar panel so you need to have a DVM rated higher than the short-circuit amperage of the panel, 10 amps is a good range. Read the amperage. This is the 'short-circuit' amps. On the Renogy 100 watt poly panel this reading should be about 5 amps. Renogy specifies 5.92 amps.

These numbers will depend on a number of variables, some under your control, some not. The readings will be highest if the sun's rays are hitting perpendicular to the panel (if you move the panel around you can see the effect oblique sun light hitting it has on it). Any shade on the panel gives you a reduced reading. Clouds, haze, smoke, anything like that will also reduce the reading.

I have not received a definitive answer from anyone about short-circuiting the solar panel, so I would keep that to a minimum. If you think about it though, the short-circuit amps is just the solar panel's maximum output which should do it no harm.

Don't touch the wires, you are dealing with 20+ volts and up to almost 6 amps!!

 

[Bela's Mom]

That is exactly how I tested mine. It did not cause any problems for the panels. I found this same method used on numerous solar forums and solar websites.

 

[AlecEdgs]

Thanks for explaining it out..