Okay this is my first post and I'm pretty much a beginner. I know electricity and working with electricity. I just bought a pikasola 100 w solar panel kit that comes with the panel, the controller, wiring, etc. Hooked it up and it works pretty well. I haven't installed on my SUV to constantly charge my battery because off of my battery I have an inverter to run house power in the suv. What I'm trying to do is on the controller you have where the solar panel connects to positive and negative and then you have where the battery connects to positive and negative. I ran the positive of one of my power outlets inside the truck directly to the solar panel input side positive on the controller. What I'm trying to do is only have power go to that outlet when the solar panel is creating energy. (In other words, only when the sun's out) I figured that when it got dark out that outlet would have no power. But instead it has power all night. I'm thinking that's because the controller doesn't have any kind of circuitry or diode that prevents the battery energy from leaking back to the solar panel if there's no light on the panel. Or that there's no circuitry in the controller that separates the input from the solar panel to the output to the battery. So what I'm wondering is, is this normal operation? Do they make a one directional filter that would go in line with the solar panel positive feed to the charge controller to only let power and flow in One direction from the solar panel to the charge controller? Thanks for any replies to this.
A little beginner help on back feed
- Thread starter Wjbell
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Don B. Cilly
Energetic energy padawan
Because the device I run in that outlet Port is a USB charger. On that USB charger is an LED light letting you know it's powered up. Having that charger plugged into the outlet that solar only lets me know that the solar panel is active, otherwise I have to get out of the truck pop the hood because my solar charge controller is in the engine compartment. Why? I guess you could call it a clever (or geeky) power indicator.
Don B. Cilly
Energetic energy padawan
The solar charger should have two connectors, one for the battery, one for the panels. And maybe a third one for small loads.
The battery connects to the battery connector. The panels to the panels one.
If you connect DC power to the panels input, the controller sees it as... panels input, and tries (unsuccessfully and counter-productively) to charge the battery with it. Try connecting it to the Load output (if you have it) instead.
[EDIT] And yes, your controller does have circuitry that prevents current going "the other way". It uses MOSFETs, which are (field effect) transistors, which are essentially voltage-controlled diodes, to generate the square wave it then uses to charge the battery.
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The battery connects to the battery connector. The panels to the panels one.
If you connect DC power to the panels input, the controller sees it as... panels input, and tries (unsuccessfully and counter-productively) to charge the battery with it. Try connecting it to the Load output (if you have it) instead.
[EDIT] And yes, your controller does have circuitry that prevents current going "the other way". It uses MOSFETs, which are (field effect) transistors, which are essentially voltage-controlled diodes, to generate the square wave it then uses to charge the battery.
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Don B. Cilly
Energetic energy padawan
If you want to know whether your panels are charging, put an LED set to the minimum charging voltage of them on the input.
If you want to know how much, connect the panels to the controller through an ammeter :·)
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If you want to know how much, connect the panels to the controller through an ammeter :·)
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I don't know how to put an LED set to the minimum charging voltage of them on the input. The way I have it set up now seems to be good IF I can have an inline diode of some sort that goes in between the solar panel output positive and the charge controller only allowing voltage to flow into the charge controller and not out to the solar panel which would mean if somehow the solar panel positive and negative and the battery lead positive and negative we're allowed for electricity to flow both ways. So if I have some sort of diode at the charge controller on the positive side of the solar panel feed and I connect my power connection to my interior charging port positive upstream from that diode then the only power coming to my interior charging port will be from the solar panel. Does such a thing exist in the solar world?
Don B. Cilly
Energetic energy padawan
Well, I must have misread... "one of my power outlets inside the truck", means just a 12V USB adapter?
With no other power going to it?
Well, maybe your controller provides some power to the input leads to... I don't know. Let me do a quick test... well, mine doesn't. With the panels connected, I have some 42V at the input. If I trip the breaker, zero.
Do you have a voltmeter? Can you run the same test?
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With no other power going to it?
Well, maybe your controller provides some power to the input leads to... I don't know. Let me do a quick test... well, mine doesn't. With the panels connected, I have some 42V at the input. If I trip the breaker, zero.
Do you have a voltmeter? Can you run the same test?
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When I say power outlet what I'm talking about is what US older guys used to call a cigarette lighter. It had constant 12 volt power from the factory. I cut the power wire and wired the outlet directly to the output positive side of the solar panel. Only.
Yes I have a voltmeter. But I don't know what you're talking about tripping a breaker. Let me do a test... When I test the power coming from the solar panel output directly into the charge controller it naturally reads the same voltage as on the charge controller screen. If I do this test at night with no light on the solar panel that same reading on the same leads is going to show the same thing because the voltage for the battery is back leaking into the leads coming from the solar panel. Which is evident by the power socket inside still powering up the USB charging unit. So it seems that the controller has no circuitry inside to stop this from happening. Attached is a picture of the test and the charge controller which is probably one of the cheapest controllers you can buy. So I'm surprised if controllers don't have function this built into it then this would probably be the one not to have it. Another question is are charge controllers supposed to have that functionality built into it to where it doesn't let power seat back into the circuit of the solar panel? If not that's why I need some sort of fix to stop this from happening.
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Don B. Cilly
Energetic energy padawan
Probably not. But if you don't want to wait until night to test it, disconnect the panels. If you don't have a circuit breaker/fuse between the panels and the controller (not a very good idea, but not essential) just unscrew one of the wires.
However cheap your controller might be, the circuitry - as I said - does prevent back-feed.
Unless it's intentional (I can't see a reason for it, but you never know) or... it's broken :·)
[EDIT] Or hey, maybe it has a common positive and switches the negative... in which case, connecting both should work.
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Okay, you're absolutely right. When I disconnect the solar panel and check the voltage at the controller on the input leads from the solar panel there is no voltage at those leads coming from the battery. So can someone please explain to me why the power outlet that I have wired from the output leads of the solar panel still has power at night when there's no sun out at all. How is that possible? The only power is receiving is from the output positive from the solar panel.
Okay I traced it down to this. If I disconnect the solar panel completely and test the leads at the positive and negative at the controller where the solar panel inputs I get 0 voltage. If I test the positive lead on the controller and put the negative on the frame of the truck I get 12.49 volts. So, without the solar panel connected and testing the positive lead where it connects to the charge controller and ground it to the frame of the truck 12 volts is still getting to that positive lead with no solar panel connected. So that tells me that somehow 12 volts is getting to the solar panel side of that controller. So that brings me back to my original question which is if I can put something in between the charge controller and the positive feed from the solar panel they prevents voltage for from going back to the solar panel and connect my positive wire that's going to my internal power socket in between that device and the solar panel itself the solar panel while getting sunlight should allow my power wire to get power and allow the voltage from the solar panel to go through that device that's designed to only allow voltage through One direction. When there's no sunlight and the solar panel isn't producing electricity to the controller the controller will then stop any electricity from going back up to the solar panel and reaching my power wire it's on the other side of that device. Device meaning a diode that only lets electricity go in One direction. That's where I'm at now so I need some kind of device some diode to block electricity going back to the solar panel because it is happening.
Don B. Cilly
Energetic energy padawan
Well, have you tried connecting both leads of the USB adapter to the panel input?
Because, sure, you can put a diode in series with the input, but it shouldn't be necessary, it would have to carry the whole current from the panels to the controller, and you'd have a (useless) ~½volt drop on it. The heat from which you would have to dissipate.
I mean, if you get zero volts with the multimeter, the USB thingy also will.
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Because, sure, you can put a diode in series with the input, but it shouldn't be necessary, it would have to carry the whole current from the panels to the controller, and you'd have a (useless) ~½volt drop on it. The heat from which you would have to dissipate.
I mean, if you get zero volts with the multimeter, the USB thingy also will.
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UPDATE: problem resolved. I saw the issue by not only wiring the positive from the solar panel but also the negative from the solar panel where it connects into the charge controller directly to the outlet inside the cab. If I just wired the positive to the outlet and use the common ground of the vehicle as the ground for the outlet power from the controller still provides the interior outlet with 12 volts whether the sun is out or not or whether the solar panel is disconnected or not. That tells me that the charge controller is backfeeding 12 volts DC from the battery side to the panel, which is why I wanted a solution to block the back feed. But for some reason if I wire my outlet to the positive and negative of the solar panel when there's no sunlight powering it it shuts off the power to my outlet. So problem solved, figured it out.
