12 or 24 volt?

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Ok, thanks for the explanation. I checked and my panel says 100watts, 21.6v and 6.10a. It is a Renogy and yes, it is prewired. It's two panels connected by a hinge allowing it to fold. There is a black box on the back of both panels and wire connecting the two black boxes together. Then one wire from each side going to the charge controller. From the charge controller, there are two with alligator type of clips I use to connect to the battery. It's really easy to use and pretty effective. I was hoping I'll be able to wire it with others, to step up the voltage in order to charge a 24v battery, but now I'm not sure if that particular panel will let me.
 
Ok, thanks for the explanation. I checked and my panel says 100watts, 21.6v and 6.10a.
Yep, that’s a no-go for charging a 24V battery.

I was hoping I'll be able to wire it with others, to step up the voltage in order to charge a 24v battery, but now I'm not sure if that particular panel will let me.
Talk to Regony but my expectation is that the only way you could do it is to remove the built in charge controller and wire in the new panel. There are people that could do that. I’m not one that is going to try.
 
Ok, thanks for the explanation. I checked and my panel says 100watts, 21.6v and 6.10a. It is a Renogy and yes, it is prewired. It's two panels connected by a hinge allowing it to fold. There is a black box on the back of both panels and wire connecting the two black boxes together. Then one wire from each side going to the charge controller. From the charge controller, there are two with alligator type of clips I use to connect to the battery. It's really easy to use and pretty effective. I was hoping I'll be able to wire it with others, to step up the voltage in order to charge a 24v battery, but now I'm not sure if that particular panel will let me.
That sounds like the 100w portable I have, although the brand is different. Each panel is 12v, 50W... wired in parallel. You'd need to wire them in series and bypass the controller. It's very easy to do. You are going to need a MPPT controller anyway to charge a 12v battery with 24v input, and all your panels will feed into this. Don't use the controller that comes with the panel.

As an example of wiring differences, a 100w 24v panel with a 100ft long wire, only needs a 10awg wire, while a 12v panel would need a 4awg wire.
 
You are going to need a MPPT controller anyway to charge a 12v battery with 24v input, and all your panels will feed into this. Don't use the controller that comes with the panel.
I thought the panels were currently 12V and rruff wanted to use a 24V.

One reason I went with 24V was that the 24V 100Ah battery was cheaper than any 12V configuration.
 
One reason I went with 24V was that the 24V 100Ah battery was cheaper than any 12V configuration.
I haven't noticed that. If true, it's easy enough to find 24v to 120v inverters, and 24v to 12v step down converters are cheap as well.
 
I haven't noticed that. If true, it's easy enough to find 24v to 120v inverters, and 24v to 12v step down converters are cheap as well.
Yep. I have a 24V-100V inverter, a 24-12V DC-DC converter and a 24V charger.
 
Get a kill a watt and check your air fryer actual usage. As well as the other devices you're planning on using.
 
One thing to consider…
I went with 24V to be able to use smaller wires. This means setting up my panels in series to get a high enough voltage to charge my battery. Series need full sunlight. You probably get the picture.
Not if the panels have bypass diodes installed which "12volt" panels do, or at least the ones I've seen. I put three panels on the top of my van and one on the drivers side and one on the passenger's side, all in series. I could tilt the drivers side panel up horizontally and the passenger side one, if I wanted, I could remove it and put it in the sun. My point is most of the time one of the panels was in full shade and my system still worked fine because the bypass diodes allowed the current to bypass the shaded panel. Maybe the residential 24 volt panels some are using don't have bypass diodes installed.....don't know. At any rate people need to quit telling people that a shaded panel stops the series connected panels from working!
 
Panel voltage is a product of panel technology, it has nothing to do with a system's battery bank voltage.

A solar charge controller converts the panel voltage and current into appropriate battery charging voltage and current.

Panel(s) ---> Charge Controller ---> Battery Bank

I pair the panels in serial, then combine the pairs in parallel to the controller.
 
A solar charge controller converts the panel voltage and current into appropriate battery charging voltage and current.
That's only if you have an MPPT controller. With PWM, the battery voltage controls the panel voltage.

MPPT is definitely worth it, as efficiency is especially important for us that have limited space. The person who revived this thread was using PWM I think, as that's what is typically slapped on portable systems.
 
Not if the panels have bypass diodes installed which "12volt" panels do, or at least the ones I've seen.
i’ve got the Renogy 175W panels. They’re about 21V/10A and will work with a 12V setup. My understanding (more on this later) is that panels aren’t “12V” panels, that they can be used to create 12v, 24v or 48v systems. You’re saying that these will work okay in the shade?
At any rate people need to quit telling people that a shaded panel stops the series connected panels from working!
Not sure if you meant to throw me in with ‘people’ but I stated clearly, at least once and perhaps twice, that all of this info was from my understanding of solar systems and that fact checking is advised.
 
Panel voltage is a product of panel technology, it has nothing to do with a system's battery bank voltage.
Agree
A solar charge controller converts the panel voltage and current into appropriate battery charging voltage and current.
Agree
I pair the panels in serial, then combine the pairs in parallel to the controller.
Can two panels be wired in series with a single panel connected in parallel?
 
Can two panels be wired in series with a single panel connected in parallel?
You probably shouldn't be agreeing because neither of those statements is correct. Wire up a 24v panel directly (or with a PWM controller) to a 12v battery, and see what happens. Don't worry, nothing will explode. The panel will run at battery voltage (plus delta v from wiring losses)... because it must. The problem is that this is far outside its optimal voltage, so the wattage will be poor.

An MPPT controller will automatically set its input at the optimal panel(s) voltage, and then convert this to the correct voltage for the battery. It's much more efficient.

Yes, you can mix series and parallel. If you put two 12v in series, you just created a 24v panel, and you can parallel this with other 24v panels.
 
Yes, you can mix series and parallel. If you put two 12v in series, you just created a 24v panel, and you can parallel this with other 24v panels.
I know you can mix series and parallel. But I wanted to know if there are 3 identical panels, can 2 be wired in series and that array wired in parallel withbthe third panel. My guess is ’nope’.
 
Yes, you need close to the same input voltage from all sources for a single MPPT.

If all you have is those 3 panels you can wire them all in series though, or all in parallel. If you do series I'd advise checking how much you lose from shading; this is something that isn't disclosed reliably, ie it isn't part of the standard specs.

High panel voltage is mostly an advantage for locating the panels far from the batteries. If the panels are not too far from the batteries, 12v isn't bad. You can mix 12v and 24v+ inputs too, you just need a different MPPT for each.
 
I'm considering a 24v battery and I found two 24v panels that I plan on putting in parallel on the roof rack. I was going to go with two 12v in series but think it'll be more efficient to go with the 24v panels in parallel.

I also want to keep some folding panels in the van so when I'm parked in a place that allows for it, I can put them out on the ground or across my hood. There aren't many folding panel options to charge a 24v battery though. I'm now considering connecting two folding panels, each with 200w, in series. The panels I was looking have these specs: Open Circuit Voltage (Voc): 22.2V, Short Circuit Current (IOC): 12 A, Maximum Power Voltage (Vmp): 18 V, Maximum Power Current (Imp): 11A, Solar Energy Conversion Rate: 19%-22%.

I'm not sure how realistic that is though. Under normal conditions how tough will it be to keep the volts high enough to charge a 24v battery using two 200w folding panels? Also, I imagine they'll degrade and likely produce less output in a few years, could that mean that they'll no longer be able to charge a 24v battery? The folding panels will likely be on a mppt and the ones on the roof will likely be on a pwm but can switch that up if necessary.

After doing a lot of research I was convinced to go 24v but now that I'm putting together a list of things to buy and how to wire it up, I'm worried, since I can't have too much solar on/in a van, it'll be more difficult to provide power to the 24v as opposed to going with a 12v. Do you think I'll have more problems with my set up trying to charge 24v, than I would with a similar set up charging 12v? What do you think, should I stick with 24v or go with 12v?
 
I'm considering a 24v battery and I found two 24v panels that I plan on putting in parallel on the roof rack. I was going to go with two 12v in series but think it'll be more efficient to go with the 24v panels in parallel.

I also want to keep some folding panels in the van so when I'm parked in a place that allows for it, I can put them out on the ground or across my hood. There aren't many folding panel options to charge a 24v battery though. I'm now considering connecting two folding panels, each with 200w, in series. The panels I was looking have these specs: Open Circuit Voltage (Voc): 22.2V, Short Circuit Current (IOC): 12 A, Maximum Power Voltage (Vmp): 18 V, Maximum Power Current (Imp): 11A, Solar Energy Conversion Rate: 19%-22%.

I'm not sure how realistic that is though. Under normal conditions how tough will it be to keep the volts high enough to charge a 24v battery using two 200w folding panels? Also, I imagine they'll degrade and likely produce less output in a few years, could that mean that they'll no longer be able to charge a 24v battery? The folding panels will likely be on a mppt and the ones on the roof will likely be on a pwm but can switch that up if necessary.

After doing a lot of research I was convinced to go 24v but now that I'm putting together a list of things to buy and how to wire it up, I'm worried, since I can't have too much solar on/in a van, it'll be more difficult to provide power to the 24v as opposed to going with a 12v. Do you think I'll have more problems with my set up trying to charge 24v, than I would with a similar set up charging 12v? What do you think, should I stick with 24v or go with 12v?
Parallel should be better if you have shading.

The folding panel I bought was two 12v wired in parallel. It was easy to wire in series for 24v. Mine are not light though.

If your panels are wired for 24v, their max power is at 36v... so they will charge 24v batteries just fine. Use an MPPT though to get the most out of them. If you use PWM, the panels will operate at the battery voltage and be less efficient.

It is not really harder to provide power to 24v batteries, but there is little reason to do it either. Charge controllers are sized by amperage, and this is the max amps, so if you have 24v batteries this will be half vs 12v batteries. So you'd save a little money there in the controller. The other thing you might gain is if you have 24v appliances, where you can reduce the wire size. If you are converting 24v to use with 12v appliances you won't be saving anything, and rather have the cost and slight efficiency loss of the conversion.

I think sticking with 12v batteries makes more sense for a small system. Also 12v panels unless you want the ability to put them far from your rig. If you do want that ability then higher voltage panels make sense. You can mix 12v and 12v inputs, you just need a different controller for each. I'd only use MPPTs regardless, as PWM throws away too much and space is limited. Of course with PWM, your batteries and panels have to be the same voltage too, while with MPPT your panels can be higher voltage.

This is what I'm planning:

Two 24v panels... probably a 100W with a 10awg 100ft cord, and a 200W with a 10 awg 50ft cord. This is so I can put them in good spots, and can park in the shade if I want.
Both feed into a single MPPT controller. Max is 300W and my batteries are 12v, so 30a is enough. If I had batteries wired for 24v, 15a would be enough.
Two 100ah 12v LiFePO4 batteries, wired in parallel.
300W 12-19v converter for the laptop.
Little 12v-12v converter for the picky roof vent.
Lights run on 12v. So will the fridge if I decide to get one.
Little 12v-120v inverter for charging small battery packs that aren't worth the trouble to convert to use 12v.
Little 12v-usb converters.
Renogy 40a DC-DC charger for when the truck is running.
 

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