Gone full Redneck

[Radian]

 

Very impressive array eh? 🤣

 

Well, I've had these panels loitering in the dark recesses of our garage for a few years now. Picked them up for beer money from a company that had gone into admin - from their showroom, hence why all different. There's a fifth 250W panel up on the 'treehouse' roof that's been running the garden lighting from a 24V LifPo4 all the while (the reason I got these in the first place). The white box lying on the deck, behind the ladder, is a more recent acquisition - an Aurora PVI-3.6-TL-OUTD (AKA ABB) inverter that a local Farmer was chucking out as it had failed. About that:

 

 

Just a bad solder joint on a relay pin that got all scorchy. Easy Peasy fix.

 

But how to test the repair? Drag out the unused panels of course! Such fun. Oh but they're all different sizes/powers... no problem. As luck would have it they're all very similar in current so in series there's no problem. Their wildly different voltages at MPPT is inconsequential. Their powers just sum. Today was overcast but it still managed 700 Watts so yes the fix worked. Now before anyone asks if I've notified the DNO, this is not permanent which got me thinking: what do inverter repair shops do to test their work?

[ProDave]

I tried to test a repaired inverter by stringing all my DC power supplies in series but could still not get to the inverter start voltage, so I had to take it out to the shed and connect it to a proper string of inverters.

[Radian]

3 minutes ago, ProDave said:

I tried to test a repaired inverter by stringing all my DC power supplies in series but could still not get to the inverter start voltage, so I had to take it out to the shed and connect it to a proper string of inverters.

 

I saw someone on YT use an isolating xformer followed by a Variac and bridge rectifier+smoothing capacitor. I don't have a Variac but then I thought about using an old shaver's transformer which is isolating and has a 120V tap which would give about 170VDC when rectified. Not much power though so didn't think it worth the bother.

[SteamyTea]

If you really want to be a local Knob, then a string of old, used car batteries.  Just go to the local council estate, should get all you need.

[Radian]

2 hours ago, SteamyTea said:

If you really want to be a local Knob, then a string of old, used car batteries.  Just go to the local council estate, should get all you need.

 

I don't need to go that far, I've got my own collection. Waiting for me to take them to the recycling centre.🙄

[markocosic]

That's pretty much my setup

 

(used panels, used 3.6 kW Aurora with £30 of new relays fitted)

 

In hindsight I'd flog the repaired inverter (has value as a convenient like for like swap for somebody with a failed one) and buy a smaller new one with the proceeds.

 

1) The low load efficiency isn't going to be ideal

 

2) It whines audibly when running at above 1kW (caps probably dying; old slow silicon inverting at a low switching frequency)

 

Can't be bothered now that it's up though. 🙂

[Radian]

Oh yes, I'm sure these inverters were the bees-knees once upon a time! But the mechanical noise is just terrible. Still, the build-quality is pretty good. If it falls over for good I've got my eye on the filter inductors and the big heatsink as parts for making a 100 Watt Class-A amplifier. ☺️