Decreesed Solar Outpur After Lightning Strike

[Walt]

A while back my wind turbine was hit by lightning. It destroyed the AC lightning arestor and blew one of the windings open in the generator along with the solar MPPT and the DC lightning arestor on my solar panels. The main fuse between the solar panels and the MPPT was not hurt but the individual fuses on each solar panel was blown open. I have since repaired and replaced the defective components but now the solar panels are only producing about 33% of the power that they originally produced. Has anyone had any experiences like this and do you have and ideas what could have happened in the panels to cause this to happen? Another problem is with the wind generator. It is only producing about 33% of it's original output , the bridge rectifiers were destroyed by the lightning and were replaced with six 150 amp rectifiers. Since then the output has been way down. Anybody have any ideas what might be going on?

Walt

[mab]

Wow that sounds like it was dramatic!  I'm now worrying as I don't have an lightning protection on my system 

No experience of this myself, but a couple of questions come to mind:-

1st:
It seems very co-incidental that all your panels AND your wind genny have gone down to 33% - are you sure it's not your meter that's reading 2/3 low?

2nd:
I assume that you have more than one solar panel; if so have you tried to measure each panel Voc & Isc and compare to spec / each other? I would expect a damaged panel to read markedly lower - and if there is a damaged panel I suppose it could pull the whole bank down.

Only other thing is to double check that you've replaced every damaged component in your system - are you absolutely sure you've not forgotten something that could be sapping the power.

m

[ghurd]

With the lightning doing all that,
how do you know the MPPT is working as it should?

The MPPT would be the first thing I would expect to blow.

I have seen cases where the wire (inside the insulation) was damaged.
G-

[TomW]

It seems very co-incidental that all your panels AND your wind genny have gone down to 33% - are you sure it's not your meter that's reading 2/3 low?

Yeah, that is a red flag to me, too.

Very odd to have 2 different systems lose output by  exactly the same amount. Especially if you are using the same metering for both.

I would suspect the metering FIRST if it is common to both systems.

Just from here.

Tom

[Walt]

A few answers. There are ten panels, each are rated 42 watts at 48 volts. The MPPT was replaced after the lightning strike. The new Mppt wasn't acting right so I replaced the replacement and it still wasn't getting the output that I previously was seeing. As for the meters they have all been replaced as well. Yesterday I added two new panels and the output increased by the amount that new panels are rated at. I have checked the output of each of the old panels and they all have about the same output.

Walt 

[TomW]

As Glen mentioned lightning can damage cable inside the insulation.

Might be worth testing short circuit amps at the panels and then again at the end of the cabling.

Any significantly less current at end of cable tells you it is in the wiring.

Just what I would do "first" before I continued grasping at straws.

Tom

[DanG]

With EPV thin-films no bypass or blocking diodes are required - but the thin films are touchy about lightning... A point-to-point test of the PV back junction boxes for VOC and ISC seems required. Are they EPV-4x panels?

Is that your array at the led3xassm tracker success story page?  If so, very nice!

[Walt]

DanG that is my array on RedRock's site, the panels are EPV's. I will do some more testing on the underground cable.

Thanks,
Walt

[Walt]

Here are two pictures of my solar tracker with six new panels on the ground that I have ties in to check the output. If my MPPT is correct there must be something wrong in the underground cable because the output is still not as good as it should be.

[Walt]

I'll try again with JPEG's

[Walt]

These are the numbers for the panels and the results after testing.
EPV-42 Panels
Parameters         Measured        Rated

Power(Max W)    46.60W          42.00W

Voltage(oc, V)    61.31V           60.00V

Voltage(Pmax,V) 46.84V           45.00V

Curent(sc, A)      1.26A             1.18A

Current(Pmax,A) 0.995A            0.940A

Testing each panel individually and in series the measurements are:

Panel(s)#     (sc, A)     Combined Amperage  Combined Voltage
1-                1.10A
                                 =1.13A                    =97.0V
2-                1.17A

3-                1.17A
                                 =1.16A                    =96.7V
4-                1.16A

5-                0.29A
                                 =0.66A                    =98.6V
6-                0.99A

7-                1.18A
                                 =1.19A                    =101.3V
8-                1.19A

9-                1.17A
                                 =1.19A                    =102.6V
10-              1.20A

The (sc, A) for the Panels 1-4 + 7-8 = 4.68A.

After disconnecting panels 5 & 6 and connecting the six new panels the mppt was producing power close to what I thought it should. I used a digital therometer and checked each connection and found one that was 35 degrees higher than any other. It was a little loose, tightened it up the tempature went down and the amperage went up.

My next question is: Should I leave the bad panels disconnected or should they still put out a usable power or will it drag the other panels down?

Thanks,
Walt

[DanG]

Sorry youre getting to re-order the install..  didn't happen to buy any spares when the ten were put in?

Wow! I think I'd be wiring one of those taller trees some distance away from the stalk tracker with a genuine lightning magnet spike and give it a web of ground wire and multiple rods to keep your kit from carrying another hit... I'd also be pondering how to use two newly retired panels for yard art and put them out for area lighting or a bird-bath, bug-zapper or other essential modern convenience...

What do nos. 5 & 6 have in common? They both at the high end at time of storm?

I have a Schott 285w panel that had lightning blow a pencil width hole through the panel back junction boxes' silicone dielectric gel encapsulate, the double-glass built panel has 2 to 5% of the blue coloring bleached from many of the cells but the 12-year old panel is still producing 90+% of rated output. The panel was one of ten (110~ pound each!) from a grid tie install that killed the roof it was on from weight and leaks...

It would be interesting if you had a remote sensing IR thermometer to have the under-spec panels

1) full sun but not in circuit
2) shaded but in circuit

to see if damaged areas were actively dragging down output instead of merely being open.

Good luck with the cable, I started burying a bare 2 or 4awg solid even alongside everything, even buried PVC conduit to help prevent near-misses from cutting holes in the insulation and allowing moisture to start a long-term failure in direct burial ground-contact runs. Too many runs going bad among neighbors "coincidentally"... Just make sure the extra ground is some inches shorter than the bundled one

[Madscientist267]

If I'm understanding correctly -

Panels 1/2 are in series with each other, as are 3/4, 5/6, 7/8, and 9/10...

Then these sets are connected in parallel, correct?

And when the 5/6 set is connected (in parallel) with the other sets, the power output drops?

IOW, when you disconnect 5 and 6, WITHOUT connecting the replacement panels, does power output increase?

If that's the case, they are essentially toast, although it looks like the damage to #6 may be minimal.

From my angle it looks like #5 took most of the hit, although since 5 and 6 are in series, they are both at fault and should be replaced.

This should be verifiable with an ammeter in series with the 5/6 set, between the panels and the rails. If the meter shows reverse current, then the blocking diode is fried at the very least. In addition, if they pull more than maybe 100mA or so, the panels themselves are leaking excessively and are pulling down the working panels, and probably themselves (which lines up with your low Isc measurements, particularly on panel 5).

As DanG pointed out, the sunlight/unloaded and shaded/loaded tests will also assist in confirming this as well, in addition to providing the temperatures. Just insert the ammeter between (for example) the positive from the 5/6 set and the positive rail, and run the light/shade tests. If it goes negative, note how much and compare notes.

If the results aren't obvious at that point, post 'em up; one of us can tell you what it means. 

FWIW

Steve