RV roof + 24v panels + Victron 100/50 for a 12 volt system?

[Juniper]

Bigfoot truck camper coming soon, have room for (3) 200 watt panels.
My limited experience has been 3 prior RVs, all with 12 volt panels and systems, self installed.

8 gauge solar pre wire installed. Looking at 600 watts solar and 3-400ah Lifepo4 with
a Victron 100/50 MPPT.

Question: would going with 24v panels help with jump starting the Victron in the early hours, and also could or should I parallel
the panels to combat the shading issues camping in Oregon.

is this plan workable? Thank you for reading this.

 

[Rednecktek]

The plan is totally workable and the 24v panels will start kicking in a bit earlier which is good because you're looking at only filling half your battery capacity at best in a single day assuming perfect sun (which laying flat isn't going to happen), no shading, and no loads.

You'll need to get a combiner box or fuses if you go with a 3p setup, but that will be the best way to avoid shading issues.

 

[Tomthumb62]

The plan is totally workable and the 24v panels will start kicking in a bit earlier which is good

So is there an advantage to 1x24v panel vs 2x12v panels 2s in shade? I’m thinking not but maybe I’m missing something.

I currently have 4x100w in 4p due to being mobile and shade issues. I’m considering replacing my MPPT with a Victron one, but hesitate mainly due to the battery +5v startup issue with those models. I’m in the shade right now and voltage is only 16.5v. Battery voltage is at 13.1v, so I need 18.1v to get the thing started. Might end up with an Epever instead. But if I were to switch to 2s2p that would help early morning but not mid day in shade.

 

[Rednecktek]

The advantage of a single 24v panel is that it is usually higher wattage per square inch due to not having the second frame and normally slightly higher efficiencies. The +5v is a common issue with about all MPPT controllers, so that's really a wash. You're also going to take a performance hit due to laying flat rather than pointing at the sun directly, figure 30% as a rule of thumb. With 4800Wh of battery and 600w of panel, you'll need 8 hours minimum of perfect sun. Kick in the 30% hit for flat panels and you're looking at 10 hours of unshaded panels to fully charge that bank.

I guess the better question is "Can you fit more panels?"

If you're needing to save some cash, I'd recommend a HQST controller over the EPEver as IMHO it performs better and is usually cheaper by a few bucks. I've had a LOT of problems and have replaced all my EPEver's over the last couple years because the hunting process is just so slow. If a cloud passed over it would stop charging, restart it's hunt for the max point, take a while to think about it, then start charging, oh look! A cloud! Let's do that again! I've had 6 hours of decent sun before and still only managed to charge less than 50Wh in that entire day because of high drifting clouds and it taking about 5-6 minutes every time anything changed to start charging again. My HQST's respond much faster and have made a world of difference.

 

[Rocketman]

600w on a 12v Victron 100/50 will be just fine. I have that mppt on 800w of panels (the most it can produce is 700w). I seldom see that high - because my panels are flat… I have my four panels in 2s2p. If going parallel- the 24v panels will be a “little” better (starts charging slightly earlier and stays charging slightly later), but it is very small.

Be sure and add fuses to a 3p array. 3p will help when near some shade - as the shade hits one panel the other two keep working until the shade hits them.

One other option could be a Victron mppt 150/45 - if you ever thought you may go to a 48v battery.

You asked if the pan is workable- yes it is. I would also add a Victron Smartshunt- so you know how much charge you have in the battery. Also add a switch or breaker from the panels to the mppt - so you can “turn the sun off” in case of reset or maintenance needs.


Now will it work for you - probably… it depends on how much power you use from your system.

Good Luck!

 

[Tomthumb62]

The advantage of a single 24v panel is that it is usually higher wattage per square inch due to not having the second frame and normally slightly higher efficiencies. The +5v is a common issue with about all MPPT controllers, so that's really a wash. You're also going to take a performance hit due to laying flat rather than pointing at the sun directly, figure 30% as a rule of thumb. With 4800Wh of battery and 600w of panel, you'll need 8 hours minimum of perfect sun. Kick in the 30% hit for flat panels and you're looking at 10 hours of unshaded panels to fully charge that bank.

I guess the better question is "Can you fit more panels?"

If you're needing to save some cash, I'd recommend a HQST controller over the EPEver as IMHO it performs better and is usually cheaper by a few bucks. I've had a LOT of problems and have replaced all my EPEver's over the last couple years because the hunting process is just so slow. If a cloud passed over it would stop charging, restart it's hunt for the max point, take a while to think about it, then start charging, oh look! A cloud! Let's do that again! I've had 6 hours of decent sun before and still only managed to charge less than 50Wh in that entire day because of high drifting clouds and it taking about 5-6 minutes every time anything changed to start charging again. My HQST's respond much faster and have made a world of difference.

Thanks for the reminder on the slow MPPT hunting of the Epever. Wouldn’t have considered the hqst until you recommend it. Sick and tired of my Renogy Rover, it nearly ruined my brand new lifepo4 battery.

 

[Juniper]

The advantage of a single 24v panel is that it is usually higher wattage per square inch due to not having the second frame and normally slightly higher efficiencies. The +5v is a common issue with about all MPPT controllers, so that's really a wash. You're also going to take a performance hit due to laying flat rather than pointing at the sun directly, figure 30% as a rule of thumb. With 4800Wh of battery and 600w of panel, you'll need 8 hours minimum of perfect sun. Kick in the 30% hit for flat panels and you're looking at 10 hours of unshaded panels to fully charge that bank.

I guess the better question is "Can you fit more panels?"

If you're needing to save some cash, I'd recommend a HQST controller over the EPEver as IMHO it performs better and is usually cheaper by a few bucks. I've had a LOT of problems and have replaced all my EPEver's over the last couple years because the hunting process is just so slow. If a cloud passed over it would stop charging, restart it's hunt for the max point, take a while to think about it, then start charging, oh look! A cloud! Let's do that again! I've had 6 hours of decent sun before and still only managed to charge less than 50Wh in that entire day because of high drifting clouds and it taking about 5-6 minutes every time anything changed to start charging again. My HQST's respond much faster and have made a world of difference.

600w on a 12v Victron 100/50 will be just fine. I have that mppt on 800w of panels (the most it can produce is 700w). I seldom see that high - because my panels are flat… I have my four panels in 2s2p. If going parallel- the 24v panels will be a “little” better (starts charging slightly earlier and stays charging slightly later), but it is very small.

Be sure and add fuses to a 3p array. 3p will help when near some shade - as the shade hits one panel the other two keep working until the shade hits them.

One other option could be a Victron mppt 150/45 - if you ever thought you may go to a 48v battery.

You asked if the pan is workable- yes it is. I would also add a Victron Smartshunt- so you know how much charge you have in the battery. Also add a switch or breaker from the panels to the mppt - so you can “turn the sun off” in case of reset or maintenance needs.


Now will it work for you - probably… it depends on how much power you use from your system.

Good Luck!

thank you for the response/ good news. I’ll probably use 70-80ah per day and will recover some back during the day. Camping trips will only be 3-5 days at a time, so I don’t need to harvest a whole bunch when I’m out, if I start with a full charge. Only a few trips will I be deep in the Ponderosas, other times there will be several hours of full sun.

Good to know that I can use the 24s and parallel them if I go that route. The Smartshunt is definitely on my list for an accurate fuel gauge! Thank you guys!!

600w on a 12v Victron 100/50 will be just fine. I have that mppt on 800w of panels (the most it can produce is 700w). I seldom see that high - because my panels are flat… I have my four panels in 2s2p. If going parallel- the 24v panels will be a “little” better (starts charging slightly earlier and stays charging slightly later), but it is very small.

Be sure and add fuses to a 3p array. 3p will help when near some shade - as the shade hits one panel the other two keep working until the shade hits them.

One other option could be a Victron mppt 150/45 - if you ever thought you may go to a 48v battery.

You asked if the pan is workable- yes it is. I would also add a Victron Smartshunt- so you know how much charge you have in the battery. Also add a switch or breaker from the panels to the mppt - so you can “turn the sun off” in case of reset or maintenance needs.


Now will it work for you - probably… it depends on how much power you use from your system.

Good Luck!

 

[Juniper]

thank you for the response/ good news. I’ll probably use 70-80ah per day and will recover some back during the day. Camping trips will only be 3-5 days at a time, so I don’t need to harvest a whole bunch when I’m out, if I start with a full charge. Only a few trips will I be deep in the Ponderosas, other times there will be several hours of full sun.

Good to know that I can use the 24s and parallel them if I go that route. The Smartshunt is definitely on my list for an accurate fuel gauge! Thank you guys!!

Yeah, the issue with +5v to start the controller was the impetus for the (3) 24 volt 200 watt panels, Rich Solar is one source I’ve looked at. I assume two 3 to 1 combiners with a fuse on the positive wire (20-30amp?) before it disappears down through the gland 8 feet to the battery compartment.