Finding the faulty cells in a Solar Panel

[guruji]

Hi guys I have made asolar panel that used to work ok but all of a sudden it gave me very little current. I read that certain damaged cells is the problem.
Is it possible to monitor the faulty cells so that I change them?
Thanks

[oztules]

yes.

If you can change them, then I assume they are not difficult to get to the leads of each one.


Face the panel to the sun, and use a current meter and short each cell in turn... throw out/replace the weak one/s from the circuit and you should be good to go.


..............oztules

[guruji]

yes.

If you can change them, then I assume they are not difficult to get to the leads of each one.


Face the panel to the sun, and use a current meter and short each cell in turn... throw out/replace the weak one/s from the circuit and you should be good to go.


..............oztules

Hi Oztules thanks for response. Is it maybe I measuring wrong with my MM? One have to short the panel to check for right amperage cause usually I just set the meter to amps and check on both sides of polarity is this ok?
Thanks

[oztules]

Your use of the meter for this application is correct.  (an interpretation thing )....I short the cells with the MM set for amps. This is your shortcircuit current......

The weak cell will show up doing this... measure only one cell  or string of cells at a time.

If you try strings first, this may narrow it down quickly to the string that is causing the trouble..... then cell by cell in that string etc etc etc. until you find the weak one/s.


................oztules

[guruji]

Thanks Oztules ok yes I will try strings first.
The thing when I bought the cells it was said that they give 1.2w. When I measured one unused it's only 0.55v at 0.15amp. Cannot understand this. So these are about 0.08w
Thanks

[oztules]

If you measured only .15A in direct sunlight...... throw em away. Not worth the mounting materials.

When you build a panel check each cell in direct sunlight for short circuit current . Only use the same current cells in a panel, as the weakest cell controls the max current in the panel.

Because materials are more expensive than the cells, I would be loathe to use less than 2w cells for 6x3 cells or 3.8w for 6x6 cells. The real estate gets very  expensive comparatively when you drop below 12% efficient cells.

................oztules

[guruji]

Hi Oztules I noticed my MM is not working right. When I used another it gave me around 1.25amp. Ok and by the way regards for your solar panel that you've build it was a great job. I saw your posted photos. Great work man and another thing we are both from islands. You're from an island near Australia yes? I'm from Malta
Thanks

[DamonHD]

Hi guruji!

Tal genn!  I have a lot of friends and have done a lot of business in Malta.  One has put a solar PV grid-tie in quite recently in his "house of character"...

Rgds

Damon

[oztules]

Yes, from an island in the Bass Strait between Tasmania and Victoria.

Caution...... if you use the leads that come with yoru MM, then expect to see poor current figures as the current gets higher.... they use spider web sized wires in most of the probes wires.....

Try and use decent sized wire from the meter to the cell for measurement. When I used the normal leads for the 6x6 cells, the 8 amps I expected looked more like 3.5A...... disappointed until I tried normal wire instead of probes. That is for a cell by cell circumstance, as you only have .5v to work with and any voltage drop in the leads will be dramatic. For full panel it is not as problematic, as you can lose a lot of voltage in the leads, and still get a ball park figure.... sort of.

If you really only have 1.25A @ .5wv, then you have only about 600mw of cell there. I would hope the leads are giving you a lousy figure, and that the real current is about 2A or more short circuit..... even then it's only a watt or so.


..........oztules

[guruji]

Thanks Oztules on the info you told me. Wow so wire thickeness plays a big role. Interesting that you said that you use other wires for MM. Ok thanks

Hi Damon you're maltese yes? where are you living right now?
Thanks

[DamonHD]

No, not Maltese, but spent a lot of time there and still working with a Fenech now!

I'm in (sunny) London.

Rgds

Damon

[guruji]

Who' s Fenech? Ok London is nice too I've been there years ago;enjoyed my stay and have friends there.
Regards
Thanks