24v solar for Adventure Trailer

thardin68

Active member
110a x 28v = 3,080 watts.

Theoretically, that's within the capabilities of your generator. But...there is also power factor to consider.

https://en.m.wikipedia.org/wiki/Power_factor

If the charger has a power factor of 1, then it will draw 3,080w from the gen to supply 3,080w to the battery. But if it has a power factor of 0.8, it will draw 20% more from the gen to supply the same 3,080w to the battery...which would exceed the 3,500w continuous load rating of the gen.

Of course, the Samlex can be programmed not to exceed the limit of the gen. But that is going to reduce the amps to the battery. If that reduction is around 20%, then you are only going to shave 1 hour off your charge time.

Personally, I would choose to save the 15% cost since you don't need a 4,000w inverter. Charging at 70a and still having 1,500w available overhead to run computer and/or a/c would be my choice.
Thanks for the feedback. I'll take your advice here.
 

dwh

Tail-End Charlie
Solar Edge is not a transformer - it's an inverter. A grid-tie inverter. Rather than running DC from the solar modules into a central grid-tie inverter, which then feeds the AC electrical panel, you stick a little grid-tie inverter on each solar module (panel) and run AC from the roof to the electrical panel.

Which works well on a house. But it won't work for an off-grid application because all grid-tie inverters require a grid supplied waveform to sync to. If the grid goes down, the inverter shuts down so as to not backfeed the grid and make a lineman's day a pain in the butt.
 

thardin68

Active member
Solar Edge is not a transformer - it's an inverter. A grid-tie inverter. Rather than running DC from the solar modules into a central grid-tie inverter, which then feeds the AC electrical panel, you stick a little grid-tie inverter on each solar module (panel) and run AC from the roof to the electrical panel.

Which works well on a house. But it won't work for an off-grid application because all grid-tie inverters require a grid supplied waveform to sync to. If the grid goes down, the inverter shuts down so as to not backfeed the grid and make a lineman's day a pain in the butt.
OK, I understand this....Thanks for the info.

2 questions -
  • Can I run the Panasonic HIT panels directly to my Solar Charge Controller without the "Optimizer"? The advertised efficiency of these units are attractive.
  • Since the Samlex 2224 has the ability to wire your solar charge controller directly, is there an opportunity to eliminate a traditional charge controller from within the trailer and mount some remote MPPT controllers directly on the panels? (I would obvioulsy need to make sure the Samlex could control the charge parameters to the levels needed. Just wondering if the purchase of this unit eliminates the need for another component within the trailer.
 

dwh

Tail-End Charlie
OK, I understand this....Thanks for the info.

2 questions -
  • Can I run the Panasonic HIT panels directly to my Solar Charge Controller without the "Optimizer"? The advertised efficiency of these units are attractive.
You *must* do that. You cannot use grid-tie micro-inverters in a non-grid-tie application. The question is whether you can buy those panels without the inverters.

Screw the efficiency. It's a red herring. Any decent MPPT solar charge controller will have similar numbers. Not that it really matters - when you are talking about solar arrays of 10kw, 20kw...or 200kw...then a lousy half a percentage point here and there can seriously add up. But a 0.6kw array, which might put out 80% of that with one panel flat-mounted...

Fugedaboudit.

  • Since the Samlex 2224 has the ability to wire your solar charge controller directly, is there an opportunity to eliminate a traditional charge controller from within the trailer and mount some remote MPPT controllers directly on the panels? (I would obvioulsy need to make sure the Samlex could control the charge parameters to the levels needed. Just wondering if the purchase of this unit eliminates the need for another component within the trailer.
Dunno. There probably is someone somewhere that makes an MPPT unit that you can stick onto a panel and then feed the output from that into a PWM charge controller. But you'd still need a charge controller, so you might as well just get a good one, like a Victron, Morningstar or MidNite.

The problem with that idea is that to eliminate the central charge controller, each unit stuck on a panel would need to be a complete MPPT solar charge controller in it's own right.
 

thardin68

Active member
You *must* do that. You cannot use grid-tie micro-inverters in a non-grid-tie application. The question is whether you can buy those panels without the inverters.

Screw the efficiency. It's a red herring. Any decent MPPT solar charge controller will have similar numbers. Not that it really matters - when you are talking about solar arrays of 10kw, 20kw...or 200kw...then a lousy half a percentage point here and there can seriously add up. But a 0.6kw array, which might put out 80% of that with one panel flat-mounted...

Fugedaboudit.



Dunno. There probably is someone somewhere that makes an MPPT unit that you can stick onto a panel and then feed the output from that into a PWM charge controller. But you'd still need a charge controller, so you might as well just get a good one, like a Victron, Morningstar or MidNite.

The problem with that idea is that to eliminate the central charge controller, each unit stuck on a panel would need to be a complete MPPT solar charge controller in it's own right.
Understood and Thanks on Grid tie controllers. Yes, the Panasonic panels are sold without them. I did not really take the time to understand the product, just looked quickly at some marketing info. I just assumed the panels were at some funky high voltage that a charge controller (like a victron) would not tolerate and those micro-inverters were a way to make them work with one. But I get ya. I want to go with the 2 most efficient standard size 24V panels I can get, but not going to go crazy getting there.

So, if I understand, the Solar controller input on the Samlex unit is just a means to make the connection to the battery "through" the charge controller. Likely a means to tidy things up? I had not read through the manual yet. Anyway, I'll read through the manual to see if I can get my head around what it does and how it does it.
 

dwh

Tail-End Charlie
Well, it's not actually a "solar" connection, it's an "external charger" connection.

What it's for is if you want to limit the max amps into the battery. So say you have the 70a internal charger plus another 50a from the solar, but your battery specs say the battery should never have more than 100a charge rate.

If the generator is running or it's plugged it to shore power, and sitting in the sun, it could have as much as 120a going to the battery. But if you run the external charge source through the Samlex and program a max battery charge current of say 100a, then the Samlex will back off its own charger to keep the max amps to the battery at 100a.

But you don't actually need that, since your battery can accept way more amps than the Samlex+solar can produce.
 
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dwh

Tail-End Charlie
And you don't need 24v panels. With an MPPT controller you can use higher voltage panels.

My Victron 100/30 can handle up to 100v from the solar and up to 30a to the battery. My panel is a 300w with a Vmp of 36v and a max voltage of 40v.

I'm using that to charge 400ah of 12v AGM.
 

thardin68

Active member
Well, it's not actually a "solar" connection, it's an "external charger" connection.

What it's for is if you want to limit the max amps into the battery. So say you have the 70a internal charger plus another 50a from the solar, but your battery specs say the battery should never have more than 100a charge rate.

If the generator is running or it's plugged it to shore power, and sitting in the sun, it could have as much as 150a going to the battery. But if you run the external charge source through the Samlex and program a max battery charge current of say 100a, then the Samlex will back off its own charger to keep the max amps to the battery at 100a.

But you don't actually need that, since your battery can accept way more amps than the Samlex+solar can produce.
Thanks. Makes sense. Starting to get my head around it...
 

dreadlocks

Well-known member
@thardin68, you need a MPPT controller thats capable of handling the voltage, it regulates it down to your charge voltage.. ~28.5v for you.. your going to need this regardless of what panels you get.. 24v panels or 60v panels you still need a controller that can do 24v and cant just hook em up to batteries.. the higher voltage house panels offer many advantages as they are more likely to be providing at least some charge current in poor lighting conditions, it might not be much but its something when the other panels will be below 28v and doing nothing.. if you needa scavange as much power as possible, its a better way to do it.

something like the: Victron SmartSolar MPPT 150/35... supports voltages up to 150V and amps up to 35A, @ 24v it handles up to 1000W of solar panels at up to 150V, so you wire the two HIT's together so they are 120VDC, as soon as those panels make more than ~28.5v they can be providing a charge.. even in shaded conditions.. and at higher voltage and lower amps you can push the same wattage through your wiring cable with less losses and smaller cables.. the Panasonics being made for home installs are more efficient and wont overheat nearly as easy... Lipo's since they take full charge will take whatever the panels give it, so if your panels are producing less power because they are too hot you'll notice it.. where as lead after working for many hours they drop to absorb voltage and if panels are blistering hot by then and reduced output you'd not really notice or feel it.
 

thardin68

Active member
@thardin68, you need a MPPT controller thats capable of handling the voltage, it regulates it down to your charge voltage.. ~28.5v for you.. your going to need this regardless of what panels you get.. 24v panels or 60v panels you still need a controller that can do 24v and cant just hook em up to batteries.. the higher voltage house panels offer many advantages as they are more likely to be providing at least some charge current in poor lighting conditions, it might not be much but its something when the other panels will be below 28v and doing nothing.. if you needa scavange as much power as possible, its a better way to do it.

something like the: Victron SmartSolar MPPT 150/35... supports voltages up to 150V and amps up to 35A, @ 24v it handles up to 1000W of solar panels at up to 150V, so you wire the two HIT's together so they are 120VDC, as soon as those panels make more than ~28.5v they can be providing a charge.. even in shaded conditions.. and at higher voltage and lower amps you can push the same wattage through your wiring cable with less losses and smaller cables.. the Panasonics being made for home installs are more efficient and wont overheat nearly as easy... Lipo's since they take full charge will take whatever the panels give it, so if your panels are producing less power because they are too hot you'll notice it.. where as lead after working for many hours they drop to absorb voltage and if panels are blistering hot by then and reduced output you'd not really notice or feel it.
Thanks, I think I've got it now. I was originally planning to go with a Victron Solar Charge controller. So I'll decide which one based on the HIT panels and verify with you guys.

I have learned a TON from this thread. A long way to go, but would like to be in a position to take advantage of Cyber Monday online purchases or Black Friday deals on the major components. I'll try to make an updated list of the current components I am considering for some additional input / confirmation. The more research I have done, the more comfortable I am getting with this plan. There are a number of RV folks using them and having good luck with them.
 

dreadlocks

Well-known member
another reason the HIT's and house panels work better in partial shading conditions, they have internal diodes.. the HIT has 4 internal diodes so its basically like 4 smaller panels in one big frame.. if a shadow from a branch comes over it then the panel's output is just reduced by 1/4 instead of completely taking that panel down like on a 24v that dont have such features because if it looses 1/4 of its power it wont do 24v anymore.. so with 2x 24v panels, if you get a branch casting a shadow your at 50% capacity with an external diode.. with 2xHIT's the same branch would just take it down 12.5% with the internal diodes.. this works with higher voltage panels because if you drop a section of cells out your still well above your minimum charge voltage.
 

dwh

Tail-End Charlie
"There was no battery management system hooked up to them, nor were they cooled."
 

thardin68

Active member
Fwiw, Dunno if you follow Rich Rebuilds on You Tube...
Those dipshitz were having excess fun with a pair of Tesla car modules.
Rich just posted a video of their latest misadventure.
Seriously, those guys are plenty smart.
They just tried to get away with skipping some basic battery rules. I suppose there is battery safety message there, dammed if I know what it is..
Thanks for the video. I understand the dangers associated with these batteries. Seeing this video was an education for sure, and honestly makes me feel a little less nervous about them. I now know what a Tesla Battery "Explosion"looks like and it was honestly less violent than I had envisioned.

I used to follow Rich rebuilds a while back. I like what he is doing and his "fight" to make the EV market more accessible. On the other hand, I feel the guy is an absolute HACK and am surprized it had not happened sooner. Going at a complete Tesla 85K pack with a sawzall and a kitchen knife does not strike me as reasonable. His cavalier attitude toward the batteries and his public disregard for safety are dangerous (and sad for the EV / Storage communities).

Rich and his crew have not given any specifics yet and there is a lot of speculation. Mostly that it was an overcharge situation with no BMS. Lack of cooling would not likely have been an issue if it was a Fractional C use.

Considering that my system will be enclosed within a metal "compartment" and I would not be sleeping over it during a charge, I feel pretty confident in moving forward with my plan. If I see some other cases of failures where proper measures are taken, I may reconsider the Tesla unit. I am committed to 24V and Lithium at this point, however.

I have moved forward making purchases to support this system, I have a bunch to time to plan it and get feedback from those more qualified than I am. I plan to learn during that process. BMS and Charging systems with correct profiles are on ,my list.
 

technomadness

New member
DO NOT charge these modules to 28v. Use a programmable MPPT controller. The victron smart solar ones are good, plus Bluetooth.


Sent from my iPhone using Tapatalk
 

thardin68

Active member
Hi all, been a while. I have procured a number of components for my system. I have:
  • Battery - Tesla S-series module
  • 057 Converter Board (for balance charger / BMS)
  • Samlex 2224 24V 2200W Inverter / Charger
  • Samlex Evo RC (Remote control & Screen)
  • (2) Renogy 300W panels
Planned but not purchased yet:
  • Victron Smartsolar MPPT 150/35 Charge Controller
  • Victron BMV-712 Smart Battery Monitor
  • Victron Smart Battery Protect 200A
I am starting to prepare a schematic to sort it all out and I am wondering if anybody has any input (other than ditch the Tesla because you will die)......

The Victron Charge Controller will be connected to the input of the Samlex, which allows for programming of the charge parameters. The 2224 includes a Temp probe to monitor battery temps and will adjust according to parameters set. The BMV-712 and BP200 I am planning to add a second layer of protection in case the Samlex unit fails to perform within the set parameters (Victron equipment will disconnect the battery if charging above set voltage or if battery is below a specific temperature). I assume I will need to set the Samlex piece with some more conservative settings and the Backup Victron components with a slightly more aggressive set-up, but still well within the limits of the Tesla Battery.

To keep things simple, I am going to skip the 24V/12V converter and just run everything off of the inverter. I have attached a schematic from the Samlex Manual for mobile installations. My system will be isolated, so no starting battery or isolator involved. I will also be managing AC input (shore power) or Generator connection manually, so the Samlex' ability to manage and auto start a generator are of no concern for me.

I will have (1) 300 Watt panel mounted to the top of my tow rig, with the 2nd panel available when set up for base camp. I will not be charging from vehicle (I have a separate dual battery system in the tow vehicle)

So thats the start of the plan. Any thoughts? ANy confirmation that the BMV / BP are necessary, or insufficient for my intent?
 

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