I don't usually park for more than a couple days (and I have dual batteries). That being said, a friend (solar installer) is "recycling" some used panels. Is a single 75w panel worth bothering with? It seems it would be right on the edge.
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Cruiserdrew
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Heck yes. Grab it! Likely will be enough for 1 fridge.
I figure 4.4 amp rating for the panel. Aprox. 25 amp hours of fridge per day (24 hours)? if I get 3.4 amps (bad light/inefficient wiring) out of the panel it would take about 7 hours to charge the battery. Just barely large enough.
If the price is right sure. Get two - and even assuming they've lost a little capacity being used you're still well over 100 watts total. And you can't argue with the quality of those.
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All depends on the weather and how the panel is pointed (or not) and your fridge efficiency (and that includes ambient temp around the fridge and airflow around it).
I've run 80W in australia in hot summer temps and that kept up with the demands of an arb 50qt with nice COLD drinks/food.
In 75F cool weather (but sunny) my arb draws less than 15 AH per 24 hour period. I upgraded to a nominal 120W+ panel, but given winter conditions (sunny) and thus sun lower in the horizon I was seeing about 80W peak production during the day. That is still a healthy 6AH going into the battery, so just a few hours to fully charge from night use and then easily keeping up with day time draw.
Note that 75W spec is in GOOD sunlight with panel facing sun and most likely a summer spec, i.e. sun near vertical to ground/panel.
Anyhow, I'd grab one (two if you can)...
cheers,
george.
I've run 80W in australia in hot summer temps and that kept up with the demands of an arb 50qt with nice COLD drinks/food.
In 75F cool weather (but sunny) my arb draws less than 15 AH per 24 hour period. I upgraded to a nominal 120W+ panel, but given winter conditions (sunny) and thus sun lower in the horizon I was seeing about 80W peak production during the day. That is still a healthy 6AH going into the battery, so just a few hours to fully charge from night use and then easily keeping up with day time draw.
Note that 75W spec is in GOOD sunlight with panel facing sun and most likely a summer spec, i.e. sun near vertical to ground/panel.
Anyhow, I'd grab one (two if you can)...
cheers,
george.
I'm confused, any help appreciated.
For context:
I have the 75/15 smartsolar paired with a 120w folding renogy blanket. These feed a single group 31 FLA in the OEM location. Our main electrical needs are simply the CFX75 dual zone and handheld devices. Measurments taken in full sun at noon on an angle durring August in Texas.
I can't seem to do better than 75watts PV under the best of circumstances (usually ~60w) even though when using a multimeter at the far end of my extension cord from the panel I measure 20v at 5amps. When I take this same measurment at the MPPT I get the same readings it sends to my phone app ~15v at 4 amps. All 10ga wire to the MPPT and panel, 6ga to the battery.
Under real world conditions in Colorado this gets me by for a couple days stationary but I thought (and think) if I was getting better performance I shouldn't have to monitor it or be concerned about the fridge cutting out. Durring our last trip of five weeks we did have cut outs twice durring extended stationary camping of more than two days and I feel like this set up should be giving me a day or two more worry free?
Do others see this kind of discrepency from panel to MPPT?
For context:
I have the 75/15 smartsolar paired with a 120w folding renogy blanket. These feed a single group 31 FLA in the OEM location. Our main electrical needs are simply the CFX75 dual zone and handheld devices. Measurments taken in full sun at noon on an angle durring August in Texas.
I can't seem to do better than 75watts PV under the best of circumstances (usually ~60w) even though when using a multimeter at the far end of my extension cord from the panel I measure 20v at 5amps. When I take this same measurment at the MPPT I get the same readings it sends to my phone app ~15v at 4 amps. All 10ga wire to the MPPT and panel, 6ga to the battery.
Under real world conditions in Colorado this gets me by for a couple days stationary but I thought (and think) if I was getting better performance I shouldn't have to monitor it or be concerned about the fridge cutting out. Durring our last trip of five weeks we did have cut outs twice durring extended stationary camping of more than two days and I feel like this set up should be giving me a day or two more worry free?
Do others see this kind of discrepency from panel to MPPT?
How long is your extension cord? Sounds like resistive voltage drop to me.
40' of 10ga but I don't see much drop in the extension itself.
Right now I'm seeing this:
At the panel 19.1v and 4.55a
At the end of extension 18.98v and 4.38a
At the mppt 16.75 and 2.2a
That seems like a big degradation of performance I'm seeing either in the four feet from where I plug in the extension to the MPPT or in the MPPT itself. I may have to pull the wire in between and see what I can see, I'm using 40a andersons to connect the extension to the wire feeding the MPPT.
Something's wrong. At the end of your extension cord you have 19V X 4.38A = 83 watts. You are saying that the output of the Victron is 16.75V X 2.2A = 37 watts? Or is that at the input to the Victron? The power has to be going somewhere. The Victron is like 98% efficient. You're losing 46 watts. If you were dissipating that somewhere as heat you would know it. What is the state of charge of the battery when you took these measurements? Any potential loads plugged in?
I'm just realizing I meant to post this in the Awesome new MPPT controller with bluetooth control for $99 thread so I appreciate you guys reply to this old thread!
My at the MPPT measurements have been taken from the set screws at the PV input location on the solar controller. I know, it's not a good result, I was thinking all was good until I really started to monitor it on this last trip because it was pretty critical since we were packed for so long a journey.
If I was able to get the 83 watts out of the 120w panel consistently I don't think I'd have an issue but 40-60 with an occasional max of 75w isn't cutting it.
I'd audit every cable connection with a multimeter until i found where that loss was going. It's being dumped as heat somewhere if you're measuring the solar input side of the controller, no other explanation.
interesting. I am using the same controller and the renogy 120W hard panels. I'm getting 108 W output with full sun and that's what the controller is reading. I haven't looked at what the output is right at the panel.
TrickyT
Hate that mud...
How are you measuring your current measurements? Something isn’t right because you are getting different current measurements at the two ends of the same cable. I’d expect some relatively small voltage drop over the 40’ of cable, but the current should measure the same at both ends. I.e., there is no such things as a “current drop.”
on another note, what battery setting are you guys using for lead acid batteries?
Well I finally broke down and actually purchased a panel. Renogy finally makes a 100 watt panel that is small enough to fit “within” my roof rack. Simple bracket with Yakima “snap arounds” will even let me tilt it. Instead of drilling holes in the roof or snorkel and finding a good place for the charge controller, using a “temporary wire harness”
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I never bought the folding solar panel because I never wanted to take up space inside my Cruiser. I considered mounting the folder on my roof because it’s too large, the same can be said for the 47”x21” long 100w panel. The newer 42” by 20” 100w panel changed all that. It fits perfectly inside the framework of my roof rack‘s sunroof cut out and is level with front fairing. The only issue is to keep the wiring “portable“ or mount the ip67 controller a couple inches below the panel and run 6‘ of 10g to the battery) or mount the controller literally on top of the lead acid battery in the very tight battery box (where battery off gassing could pose a hazard) or the back side of the battery box which exposes the controller to higher engine temperatures. In cab mounting is not an option since house fuse block/distro is in engine bay. Roof to engine bay would be accomplished by running wire through the cheap China snorkel.
This thread was very helpful for me, and I thought I'd share some photos. It all started when I got tired of regular coolers--yes the ice melts but what's almost more frustrating is having to hunt through it all to find that one stick of butter or last can of beer. So I got a National Luna fridge and then the accompanying solar + battery. Battle Born LiFePO4 100Ah, 200W Renogy, MPPT, etc etc. Got the battery and electrical strapped to a board that screws into my rear cargo plywood. Ran a ~6ft cable with MC4 on either end through one of the grommets in the floor and it is mounted next to the trailer plug.
The idea is that I can put the panels wherever I need them on the ground and run a longer cable to the 6ft outside-inside jumper which goes to the Pelican box holding the electronics. Did an adjustable PVC frame for each panel to get the best tilt angle. Trouble is, I like to camp with a big 10x14 canvas hot tent (and I am challenging myself to pack everything inside--hence removing 2nd and 3rd row seats).
Chuck box, fridge, battery do great in the cargo area. Attic is a shelf from Menards (I'm very cheap/home brew/diy here...). Shelter, cots, chairs, etc get ratchet strapped using the 2nd row seat mounts. All of this works great, except the big glass/metal solar panels don't pack well inside. So I cooked up some bracketry and mounting that uses the existing roof rack rails. It's was my idea to put the panels here for transit and hopefully get some power during. I like keeping the entire fridge circuit separate from the vehicle.
Basically, from each side of the truck you can lay the inside edge of the solar panel frame into the bracket and catch 3 bolted in studs. Then tilt down and rest on the outside bracket which has two through-holes to accept 2 pins with integral wire catches. I still need to make some kind of air dam and resolve the wiring to the interior, but it's going well so far. If I make another cable that uses thinner gauge ( I used 10AWG ), then I could pass through the gap that the upper half of the rear hatch makes with the body. Right now it would just pinch the wires. But if I could do that, then I can run down the rear hatch channel and behind the bumper and catch my existing 6ft jumper. Hope this helps others! This stuff is very home brewed hardware store quality, but it's quite sturdy and I just don't have access to the machine shop equipment I'd otherwise like to apply to this project!
The idea is that I can put the panels wherever I need them on the ground and run a longer cable to the 6ft outside-inside jumper which goes to the Pelican box holding the electronics. Did an adjustable PVC frame for each panel to get the best tilt angle. Trouble is, I like to camp with a big 10x14 canvas hot tent (and I am challenging myself to pack everything inside--hence removing 2nd and 3rd row seats).
Chuck box, fridge, battery do great in the cargo area. Attic is a shelf from Menards (I'm very cheap/home brew/diy here...). Shelter, cots, chairs, etc get ratchet strapped using the 2nd row seat mounts. All of this works great, except the big glass/metal solar panels don't pack well inside. So I cooked up some bracketry and mounting that uses the existing roof rack rails. It's was my idea to put the panels here for transit and hopefully get some power during. I like keeping the entire fridge circuit separate from the vehicle.
Basically, from each side of the truck you can lay the inside edge of the solar panel frame into the bracket and catch 3 bolted in studs. Then tilt down and rest on the outside bracket which has two through-holes to accept 2 pins with integral wire catches. I still need to make some kind of air dam and resolve the wiring to the interior, but it's going well so far. If I make another cable that uses thinner gauge ( I used 10AWG ), then I could pass through the gap that the upper half of the rear hatch makes with the body. Right now it would just pinch the wires. But if I could do that, then I can run down the rear hatch channel and behind the bumper and catch my existing 6ft jumper. Hope this helps others! This stuff is very home brewed hardware store quality, but it's quite sturdy and I just don't have access to the machine shop equipment I'd otherwise like to apply to this project!
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