Nature Power solar panel troubleshooting

[Mickeyrouse]

I have two Nature Power 180 watt solar panels 1 year old, using a Victron controller. Though the implied combined amperage output on a clear day at noon is about 18-20 amps, the Victron tells me I’m getting at max about 3 amps. I know I won’t get the theoretical max, but 15% of rated output is pretty puny on a clear day at noon. My voltmeter says each panel is putting out 21.3 volts, and the voltage measured at the Victron input terminals is the same. I’ve got the panels joined with a “ Y” connector, using MP-4 connectors. The connectors seem to be industry standard, but they’re pretty clunkly.
The Victron manual doesn’t have a troubleshooting section. Anyone have any ideas?

[donradcliffe]

Sounds like you may have been scammed. From the Nature Power website
SPECS:
Solar Panel Solar
Panel: Crystalline
Maximum Power: 180 Watt
Voltage at Pmax(Vmp): 18.94 V
Current at Pmax(Imp): 9.51A
Open circuit voltage(Voc): 22.31 V
Short sircuit Current(Isc): 1.34 A

These numbers just don't compute. Short circuit current is ALWAYS higher than the Imp, and the 3 amps of Imp you are getting is pretty close to 2 panels worth of Isc.

If you can disconnect the panels and measure the short circuit current with a clamp on ammeter, it should be about 10 amps for each panel.

[tenchiki]

How fully charged is your battery bank? How well aimed are your panels? You will only get close to full power output if the panels are pointed directly at the sun on a clear day, and the battery bank is not close to full charge.

[Mickeyrouse]

Originally Posted by donradcliffe

Sounds like you may have been scammed. From the Nature Power website
SPECS:
Solar Panel Solar
Panel: Crystalline
Maximum Power: 180 Watt
Voltage at Pmax(Vmp): 18.94 V
Current at Pmax(Imp): 9.51A
Open circuit voltage(Voc): 22.31 V
Short sircuit Current(Isc): 1.34 A

These numbers just don't compute. Short circuit current is ALWAYS higher than the Imp, and the 3 amps of Imp you are getting is pretty close to 2 panels worth of Isc.

If you can disconnect the panels and measure the short circuit current with a clamp on ammeter, it should be about 10 amps for each panel.

That data agrees with my single panel data. I am computing The max theoretical output for both panels.

I’ll try the clamp reading.

[Mickeyrouse]

I’ve used a Fluke clamp meter to test output: nada. zilch. Zero. Batteries are fully charged, with high charger output for about 5 days. The panels lie more or less flat on my bimini, so I realize that won’t be full power right there. Since we’re constantly moving around, this mornings 20 degree positive angle may be this afternoon’s 20 degree negative angle, so I figure leave them flat more or less and things will average out. Yet, looking at the Victron app and checking on history, at time the output is hitting around 7 amps at some times in the last 30 days. My most recent reading was at about 4:30 on a scattered clouds kinda day. Is there a minimum threshhold at which point output stops? So if an improper angle costs me 20 percent of output (just a SWAG estimate) and max theoretical from both panels at 19 amps, I should see prox. 15 amps. How much will scattered clouds at 4PM cost me? The panels are semi-flex, and have assumed a semi-permanent shape. They’re clear of obstruction most of the day except for the shadow of the backstay, prox 1/2x 58”. That may cost me at most 1% of power potential, but only for that part of the day the backstay shadow is on the panel. Worst case there is it costs me .2 amps.
So: what has the experience been amongst forum cruisers and users with Nature Power? Are these two panels just a couple of random duds? Are there other makers of semi-flex panels that have a more consistent or reliable record? Or am I just encountering the reality of solar power versus the hype?

[Pete7]

Certainly something odd. With a theoretical 360w of solar you should be seeing 10-15A regularly when the batteries are charging. So is this the problem? the batteries are full and the Victron controller has cut the charging to stop damaging the batteries perhaps?

Which Victron controller do you have? and can you upload some screen shots of the numbers. Particularly covering the bulk, absorb, float icon. What have you used for values in the MPPT settings?

This is 300w of solar during an April mid day at 51'N and kind of what I would expect to see.

So if the batteries are full and the MPPT asleep, then try adding a large load like the inverter with a kettle and watch what happens. Voltage should drop and the MPPT switch to bulk charge and ramp up the power being generated.

If that doesn't produce any useful numbers, try removing the y connector and just plug one panel in at a time and see what difference that makes.

Pete

[Mickeyrouse]

Good suggestions. I’ll be out of town the next two weeks, so I’ll check it when I get back. I’ll let you know what I find.