0 volts from panel... anything I can do?

[Captain Bill]

I just reread the thread to make sure I haven't missed anything, but maybe there's an assumed fact that is incorrect. I think everyone assumes you have a 12V battery bank. Is that correct?

[thomm225]

You can troubleshot this with just voltage checks.

See what the voltage is on the battery side of the controller.

When the panels are first hooked up the voltage on both sides of the controller should be about equal until you batteries charge to the float setting voltage. On my 12 volt system, I have my float set at 13.7 volts

After the batteries charge to 13.7 volts on mine for example, the voltage on the panel side will slowly start to increase as the controller allows less and less current (charging) to flow to the battery until the voltage (panel side) nears the open circuit voltage. I've seen mine near 21 volts but usually at 19 something which the battery side still at float or 13.7

I'm using a PWWM controller. You may have an MPPT which is better but different.

Sounds like your panel side is good. Now just check the voltage out of the controller battery side.

Are you sure your panels are in parallel and not series. Panels in parallel have the same voltage output as a single panel but the wattage is additive. I have a 65 watt panel and a 20 watt panel (both 12 volt panels) which equals an output of 12 volts and 85 watts

Sounds like your panels might be in series since your voltage is doubled.

[basssears]

Am told I don't say it enough so will say thank you to everyone who has replied to my original post, your attempts to help are much appreciated.


This diagnosis is going on hold until I get some time... we have little time on the boat (we live 800 miles from the boat) so am just sailing now and will try to sort this out later... current plan is to bring both panels and the charge controller home and go through everything one careful step at a time... if all seems well then I know it's the relatively small amount of wiring I will leave on the boat.


To clarify my setup, I made my own folding panels. I took two 50w panels on each side of the boat (so totalling, in theory, 200w) and connected each pair of 50's in series... so 100w @ 24v on each side of the boat... then connected those in parallel where they feed into a Victron 75/15. So assuming everything is working I should have two 24v 100w panels connected in parallel going to an MPPT controller.


What I get, over the solstice at 48.5N is about 50-60 watts of total power in according to the Victron app on my phone (which connects by the Bluetooth dongle to the charge controller). Based on my voltages and estimated use (I don't have a built in ammeter) I would say that the watt/hours in shown by the Victron controller's app are accurate... I'm not at dead batteries but am slowly losing ground even though our electrical needs are relatively light... if I was actually getting the 150-160w I might expect this time of year and the controller was just misreporting the wattage in I think my battery SOC would be higher than it is.


So having discovered that my current multimeter on the boat is kind of junk (one of the many challenges of having a boat 800 miles from home is trying to develop a second, semi-decent set of tools) I think my best bet is to haul everything home and go through each part of the setup one methodical step at a time.


But this is the second or third time I've posted to CF while traveling and needing help and every time people have come through and helped me out, so thanks again, I really appreciate the input.


-- Bass

[Paul Elliott]

Originally Posted by basssears

I'm not at dead batteries but am slowly losing ground even though our electrical needs are relatively light... if I was actually getting the 150-160w I might expect this time of year and the controller was just misreporting the wattage in I think my battery SOC would be higher than it is.

So have you put together a realistic power budget? "relatively light" can cover a wide range. With your 200W of solar panels you might be getting 1000Wh per day, or around 80 Ah / day (@12.5V) of charging. This isn't all that much if you are actually using the boat.

So yes, do take accurate measurements of your panels and charger, but also do a realistic power budget. Perhaps everything is actually working as it should?

[basssears]

Originally Posted by Paul Elliott

So have you put together a realistic power budget? "relatively light" can cover a wide range. With your 200W of solar panels you might be getting 1000Wh per day, or around 80 Ah / day (@12.5V) of charging. This isn't all that much if you are actually using the boat.

So yes, do take accurate measurements of your panels and charger, but also do a realistic power budget. Perhaps everything is actually working as it should?

Thanks Paul, I have worked out my power usage and am comfortable with it. I know that even fully functioning my 200 watts is just delaying the inevitable need for outside power (motoring somewhere, marina for a night etc) and am fine with that, I am not at the point financially (or, honestly, space wise on a 32' boat) to be trying to cover all my power usage with solar, just trying to add some free amps when I can.


It's mostly the idea that my 200 watts of panels are putting out a total of 55-65 watts in full summer solstice sun (with one 100w panel trickling in a measely 15 watts) that makes me think something is wrong with the charging side of this setup.

[Zil]

You would be well served owning a clamp over dc amp meter type multi-meter. such as; https://shop.marinehowto.com/product...amp-volt-meter

[basssears]

Originally Posted by Zil

You would be well served owning a clamp over dc amp meter type multi-meter. such as; https://shop.marinehowto.com/product...amp-volt-meter

My clamp over meter is not serving me well, because it didn't make it on this trip and is at home, only have a dinky older multimeter to try to test with.


Although, my one issue with the clamp on meters is I usually run duplex wire so can't use it very effectively.

[basssears]

Originally Posted by Captain Bill

You nee to connect an ammeter across the wires and see if you get anything close to the specified amps at noon on a sunny day. The short circuit amperage is known as the Isc rating and should be on a label on the back of the panel. It will not hurt the panel to do this, just make sure your ammeter is rated for the number of amps you expect. A high resistance break in the panel or in a wire can allow voltage to build up but cannot carry any current.

Do you know if it's safe to test short circuit amperage using a clamp on multimeter? Can I just jumper positive to negative then clamp my (rated to 400a) meter over that jumper?

[Captain Bill]

Originally Posted by basssears

Do you know if it's safe to test short circuit amperage using a clamp on multimeter? Can I just jumper positive to negative then clamp my (rated to 400a) meter over that jumper?

You can safely do this without worrying about damaging the meter. The wire needs to be big enough to carry about 5 amps. Any piece bigger than about 16 gauge should do. If your clamp-on is AC only you may or may not get a reading and it may not be accurate if you do. Many cheap multimeters can handle up to 10 amps of DC which is good enough for your purposes. Harbor Freight sells one for 5.99. Set it for DC amps and attach it directly across the + and - terminals on the panel. When measuring amps some meters require the + lead to be plugged into a special socket on the meter, so be aware of that. Your panel under ideal conditions will only put out a bit over 4 amps. In certain conditions ( ice cold panel very bright sun light and cloud edge effects) you might see 6 amps but it's unlikely. As the panels are current limited there is no problem testing them this way, but make sure they are not connected to anything else when you do this test. what you are looking for is an amp reading somewhere above an amp and a half depending on conditions at the time you do your test. If you see something like .05 your panel has a serious problem. It is unlikely all of your panels will have a problem unless you have taken a nearby lightning strike. I had a friend that lost 2 panels on one side of his boat and the ones on the other side were fine. I helped him test his panels which were showing normal voltage but producing only .01 amps in the amp test.

[thomm225]

You may just need to redo all your connections.

My panels are hooked in parallel on a small PWM Controller that shows it has input from at least on panel

I have a 20 Watt Panel and a 65 Watt Panel for 85 Watts.

Sometimes though when I return from a sail weekend or during my weekend sail, I'll notice that my batteries aren't charging back up very fast from the night before (I usually run a fan off my inverter all night) and in the past it's been a connection problem with my larger panel (and once it was a broken wire on my larger panel)

The fix it usually just redoing the connections.