My score today is not test equipment, but it's related. Maybe these will end up powering my test gear?
20160331 Thur
Being given 8 big solar panels
I walked the few houses up to the shops to get milk for my breakfast this morning. On the way back, there was a van parked almost directly opposite my house. A guy was loading what were obviously old solar panels into the van, with a couple still leaning against the front street fence still to go in the van.
Ladder against a house there, shiny new panels on the roof.
On the principle 'grasp potential opportunities in the moment', and that he was obviously finishing up and about to leave, I quickly walked over and said hi, are you disposing of those panels, and could I possibly have them?
I then went into detail, about being a retired electronics engineer, and wanting to examine a bunch of old panels to see how they degraded, what kinds of faults, etc.
He had to phone his office to ask, and while waiting for them to call back he explained they were a warranty replacement, since the house had been struck by lightning, and they were probably dead. I said I didn't care, in fact that made them more interesting. (I was thinking it unlikely they were ALL dead, plus I would actually like to see the result of lightning-struck solar panels.) I asked how often that happened, and he mentioned only ever having had to do this about 6 times, in several years.
We talked about the idea of mini-inverters per panel with 240VAC outputs in parallel, vs panels in series and one bulk inverter. I mentioned the idea of a system with sense wires to each panel, logging stats of individual panels. He says there is such a thing, google "Tigo". Got his business card.
We stacked the panels against my front fence. He asked if I had a multimeter and I laughed and offered to show him my electronics workshop. But he was in a rush to another job and had to leave. He gave me the box of mounting hardware, and a couple of rails. he'd installed only 6 new panels, presumably higher efficiency equivalent to the 8 old ones.
I moved the panels to the side of the house, then had breakfast. Afterwards moved them to the back yard, laid out in the sun. Cloudless sunny day atm. By 11:30am I'd tested each one and recorded values. Open circuit V, and short circuit Amps only. Wrote values on panel frames in marker pen, then copied to paper, numbered them on paper in rough order of functionality, then wrote the unit numbers on the panels too.
The sorted data:
Voc Isc(A)
1 30.0 8.2
2 29.7 7.2
3 29.9 6.2
4 20.2 8.0
5 20.6 7.3
6 20.3 7.2
7 19.9 7.4
8 10.3 6.5
Number 8 is pretty dead, the others all seem not bad, and quite worth using.
Figures taken with the panels manually tilted up to approximately point at the sun. But a few minor shadings - long grass, clothes hoist, etc.
They all have some dirt on the glass, and small lichen growths. Cleaning them may improve the figures a bit.
Panel model info (from label)
-----------------------------
Ningbo Qixin Solar Electrical Appliance Co Ltd
Type: SL190CE-27P
Peak Power (Pmax) 190W
Production tolerance: +-5%
Max power current (Imp) 7.15A
Max power voltage (Vmp) 26.56V
Short circuit current (Isc) 7.65A
Open circuit voltage (Voc) 32.56V
Weight 17.0Kg
Dimensions 1485 x 990 x 40mm
Wind resistance 2400 Pa
Just for the thrill of free everything, I used that multimeter I was given recently, and had fixed the internal water-corrosion it had.
Home
Help
Search
Login
Register
