Building a small camper with my son. I have begun planning my power and could use some suggestions.

[McGee]

Hi all! I tend to overthink things and it slows me down - I'm hoping I can get some good suggestions here.

My son and I are building a small trailer out into a teardrop/camper. So far I have ordered the following:
(2x) 12V 100Ah LiFePO4 batteries (going to run them in series for 24v)
(1x) 200W/24V Solar Panel (going to roof mount with the ability to unlock each side and tilt to adjust for best angle when stopped)
(1x) Giandel 24V Sine Wave Inverter - 1200W/2400W

I know I will need to step down the 24V to 12V and run a fuse box/switches, etc and I intend to have a cooler, TV, lights, and fans running on that DC (maybe more)

I still need a Solar Controller - suggestions? (I have attached the SPECS of the solar panel - I also plan to re-use the system on something bigger in the future so I can add a duplicate panel for 400W @ 24V - and add 2 batteries for a 24v 200Ah storage - if that effects suggestions)

I would also like to be able to plug in and override the solar and have the shore power or generator power charge the batteries, if needed. I guess I am a little confused about what I need to make that happen. (EDIT: I have just learned today that there are inverters AND inverter/chargers...I only ordered an inverter)

We are excited to learn and I am grateful to have a huge community like this for support! Thanks for taking the time to help out!

 

[Rednecktek]

Is there a reason you're going for a 24 system for this? With as small an inverter as you're looking at there's no reason you couldn't go with a pure 12v system. Get a decent MPPT controller (EPEver, HQST, Renogy, etc.), nothing too fancy (Victron, Samlex, etc), and go for a pure 12v setup. The 24v-12v step down converters have issues with startup surges like compressors (fridge) or fans or the like. Being able to have the batteries take that hit is preferable to try to feed a really large converter.

The rule of thumb for panels to SCC is 10a of SCC per 100w of panel @ 12v, so at least a 20a, but the price difference between a 20a and a 40a is so small it's worth it to have that expandability later, especially with how much battery capacity is there.

 

[McGee]

Is there a reason you're going for a 24 system for this? With as small an inverter as you're looking at there's no reason you couldn't go with a pure 12v system. Get a decent MPPT controller (EPEver, HQST, Renogy, etc.), nothing too fancy (Victron, Samlex, etc), and go for a pure 12v setup. The 24v-12v step down converters have issues with startup surges like compressors (fridge) or fans or the like. Being able to have the batteries take that hit is preferable to try to feed a really large converter.

The rule of thumb for panels to SCC is 10a of SCC per 100w of panel @ 12v, so at least a 20a, but the price difference between a 20a and a 40a is so small it's worth it to have that expandability later, especially with how much battery capacity is there.

Thanks. My reasoning for the 24V was that it was safer, more efficient, and required cheaper wiring - and, that is honestly just an opinion I have acquired from watching videos in spare time. Is there any value in that? I had not considered the 24v->12v causing issues. The largest item I will run from the inverter is a small 700-800w microwave intermittently. The biggest draw from the DC would probably be a small 40-50qt freezer/cooler on 24/7.

I also plan to part it off eventually to a better system adding something like another 200w panel and increasing the inverter to a 2k/4k.
I was going to do a 12v but originally wanted a 5K BTU AC unit on the trailer - I scrapped that A/C idea when I saw the battery Ah I would need to keep it on all night (I'm in South Florida). Ended hearing a lot about the 24V systems on videos and shifted by plan toward that. I actually still have a 12V 2000/4000 Giandel on the way that I plan to use on a shed/cabin, or some other project.

 

[McGee]

I'm now realizing that if I want to charge off of the times we might have shore power available that I need an inverter/charger and that the 2 inverters I have purchased are not chargers...

I am seeing products on the market that have MPPT controllers together with inverter/chargers. Would those be a good avenue for what I am trying to achieve?

 

[Rednecktek]

You'll have to figure out what the startup surge on that fridge is and size your converter appropriately. You'll need a DC amp clamp with inrush monitoring to get an exact number.

It's worth looking at the coat of wire and fuses for 12v VS the cost of a well sized converter just to have that data point.

If you're planning on a 3k-ish inverter later then 24v makes more sense, but I question throwing out an inverter later and replacing it.

However, if you did a 12v system now, those same wires and fuses will be the right size for your 3kw/24v setup later.

Just some thoughts. Either way get all the panels you can fit, you've got 2400wh of battery there and at the average of 4hrs of good sun a day that's 600w of panel to charge those in a day under perfect conditions.

 

[Rednecktek]

I am seeing products on the market that have MPPT controllers together with inverter/chargers. Would those be a good avenue for what I am trying to achieve?

Basically you're looking at an AIO like the Growatt 3kw or MPP 2424 that would do your solar panels, invert from the battery, and you hook up your shore power plug to the AC input which would feed your AC and charge the batteries at the same time.

 

[McGee]

Basically you're looking at an AIO like the Growatt 3kw or MPP 2424 that would do your solar panels, invert from the battery, and you hook up your shore power plug to the AC input which would feed your AC and charge the batteries at the same time.

I have the space to add 2x more 60W 24V panels from the same manufacturer on the roof. That will only put me at 320w @ 24V for panels.
Getting my head wrapped around the equipment needed to plug in and charge is important. We are pretty frugal and will be testing it outside of our house for a few days/nights to really get an idea of how the power use goes. In theory we won't drain the full charge in a few days of use - allowing the panels to supplement and occasionally finding a plug-in option along the way, if needed.

 

[McGee]

Basically you're looking at an AIO like the Growatt 3kw or MPP 2424 that would do your solar panels, invert from the battery, and you hook up your shore power plug to the AC input which would feed your AC and charge the batteries at the same time.

Looks like I should probably return the 2 inverters and go to an all in one like the MPP 2424 you've suggested above.

 

[Rednecktek]

have the space to add 2x more 60W 24V panels from the same manufacturer on the roof. That will only put me at 320w @ 24V for panels.

With that you'll need a second SCC involved. If you try to combine those panels your 200w will be dragged down to the 60w levels. You can't get another 200w panel on there? Bummer.

 

[McGee]

I could add a 2nd 200W 24V to be a match. I would have a couple of inches of overhang and would have to modify the roof design - I can turn them into part of a small overhang. (approx. 2" over on each side)

 

[McGee]

With that you'll need a second SCC involved. If you try to combine those panels your 200w will be dragged down to the 60w levels. You can't get another 200w panel on there? Bummer.

I appreciate all of your help.

One last question here tonight! I am looking at the $600-$800 MPPT 24V/110 inverter/chargers and wondering this: I can get a PWM 24V/110 inverter/charger for about $250-$300. I can then add that 2nd panel to bring my panels up to a matching pair of 200W/24V panels.
I know that MPPT is more efficient than PWM - but wouldn't the extra panel bringing it to 400w into the PWM controller generate far more than a 200W panel into an MPPT controller?

The obvious answer here being to add a 2nd 200W panel and still buy the MPPT inverter/charger - but it would save about $400-500 now to go with the PWM - and like I said before? I plan on pulling some of this out to use on a cabin project in the future.

So many damn options - this is the ultimate rabbit hole. I just want to keep learning and getting hands on with it. I will better understand it as time goes on - but it is definitely challenging now to sort through.

 

[Wakintx]

I appreciate all of your help.

One last question here tonight! I am looking at the $600-$800 MPPT 24V/110 inverter/chargers and wondering this: I can get a PWM 24V/110 inverter/charger for about $250-$300. I can then add that 2nd panel to bring my panels up to a matching pair of 200W/24V panels.
I know that MPPT is more efficient than PWM - but wouldn't the extra panel bringing it to 400w into the PWM controller generate far more than a 200W panel into an MPPT controller?

The obvious answer here being to add a 2nd 200W panel and still buy the MPPT inverter/charger - but it would save about $400-500 now to go with the PWM - and like I said before? I plan on pulling some of this out to use on a cabin project in the future.

So many damn options - this is the ultimate rabbit hole. I just want to keep learning and getting hands on with it. I will better understand it as time goes on - but it is definitely challenging now to sort through.

You can choose not to. Connect solar panels to the pwm inputs of the AIO and purchase a mppt SCC to hookup to charge the batteries. The rest of the AIO functions as charger, inverter and transfer switch. PWM "works" but mppt is better

 

[Rednecktek]

If you get a charger/inverter that already has an MPPT in it and 20a or more, you won't need another controller for the second panel. The only time you'd need another controller is if you try to mix & match different size panels like a 200w and a 60w.

Link to the 24v PWM unit please? I seem to think that EcoWorthy makes PWM based AIO's, and it would be OK, but don't be suprised if it dies before too long. Either way, throw up a link and let us take a look. As a learning project on a budget it would probably be fun and cheap.

 

[McGee]

If you get a charger/inverter that already has an MPPT in it and 20a or more, you won't need another controller for the second panel. The only time you'd need another controller is if you try to mix & match different size panels like a 200w and a 60w.

Link to the 24v PWM unit please? I seem to think that EcoWorthy makes PWM based AIO's, and it would be OK, but don't be suprised if it dies before too long. Either way, throw up a link and let us take a look. As a learning project on a budget it would probably be fun and cheap.

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www.vevor.com

I know VEVOR can be dicey but I have 2 pieces of equipment from them in my ice cream shops and have never had an issue. I'm curious to see your opinion(s) on it. I see a 30-day return policy but I am not finding any warranty.

 

[Rednecktek]

I've got a few of their diesel heaters as well. For a starter project it should work fine. Put the 2 panels in parallel to it and call it a day.

 

[McGee]

You can choose not to. Connect solar panels to the pwm inputs of the AIO and purchase a mppt SCC to hookup to charge the batteries. The rest of the AIO functions as charger, inverter and transfer switch. PWM "works" but mppt is better

Interesting - so I could essentially bypass the PWM element and add a moderately priced MPPT?

 

[McGee]

I've got a few of their diesel heaters as well. For a starter project it should work fine. Put the 2 panels in parallel to it and call it a day.

Yeah at that price I may as well go for it - can always find a use down the road. When I move soon (we're going to TN mountains) I will have already sold my house here and will have more F-U money to play with and the knowledge gained on these projects along the way.

 

[Rednecktek]

Interesting - so I could essentially bypass the PWM element and add a moderately priced MPPT?

You could, but it's not necessary. The cost difference between tge PWM unit + MPPT controller gets you right into the price range of an MPPT based unit, but adds more complexity and wiring.

Remember that you've still got to get a 24v-12v converter involved.

 

[McGee]

You could, but it's not necessary. The cost difference between tge PWM unit + MPPT controller gets you right into the price range of an MPPT based unit, but adds more complexity and wiring.

Remember that you've still got to get a 24v-12v converter involved.

Sidenote: I am at the checkout and it states there is a 12 month warranty, at least.

 

[Rednecktek]

Pretty standard warranty. Considering the cost of the extra panel and 24v-12v converter going with the Vevor isn't a horrible choice.

If it help you learn it's something, plus it sounds like a pretty fun project.