overthinking every detail building a system

[lido]

Hi group
so far learning about all this has been a fun, yet confusing, yet interesting subject.
I have many questions about a setup I would like to build on a camper.
first I want to throw out my plans and thoughts, then I will list questions and any help from you experts will be great and possibly make me rethink my build.

the roof of my camper will be near 60 inches by 96 inches so 5' x 8'. I want to put 3 200 watt solar panels on top I currently have 1 newpowa 9BB 200w solar panel but plan to buy 2 more. the stats are

• Max Power Output(W): 200W
• Voltage MPP Vmp(V): 18.60V
• Current MPP Imp(A): 10.76A
• Voltage Open Circuit Voc(V): 21.8V
• Short Circuit Current Isc(A): 11.47A

I plan on buying a 300ah lifepo4 battery [possibly 2] and that's to power the camper i.e basic 12v lights, small cooler/fridge that uses 40w not often, 400 watt air conditioner from Ecoflow wont run much due to small camper size.

I originally was going to get the panels, hook them in parallel and a 60A Bougerv or similar MPPT charge controller with Bluetooth to see the stats and hook it to the battery.
1. with those numbers does that equal 18v and 33 amps?
2. If you hook them to a wire 3 into 1 branch connector the 3 wires going in would be fine but the 1 wire out would need to be 8AWG to go to the Charge controller however I was unable to find a larger branch, they seem to be 10AWG or 12AWG. so if you hooked the 3 panels in would it melt the 1 wire leading out because of high amps?
3. would hooking 2 panels to a 30A MPPT and 1 panel to another 30A MPPT then connecting both to the 1 battery make any sense?

now at this point hooking panels in series would be better however I often camp in wooded areas and shade and clouds would kill all solar depending on time of day.

Now we can throw another thought into the system I have a Bluetti ACMAX power bank that's 2kw.
It can accept Solar input of 900W Max., VOC 10-145VDC, 15A meaning I would have to run the panels in series due to 15A limit.?.

4. would having the Bluetti get charged by the solar panels and then using it to charge the 300ah battery with say a 40 Amp battery charger make it A easier setup?

I'm going to stop now so I can hear your thoughts and comments and go from there.
thanks

 

[MichaelK]

Slow down and first come up with a number of watthours you expect to consume in a day. My gut feeling is that only 600W of solar will be inadequate. Will the panels be mounted flat on the roof of the camper? If yes, I'd de-rate them to only 60% because of the less than optimal angle to the sun. So, 600W is never likely to put out more than about 360W in the real-world. Not enough to run the air-conditioner.

It's fundamental conflict of interest when going camping in the summer. You want to park the camping the the shade so it stays cool. You want to park it in full sun to take advantage of full sun. They are mutually exclusive. One option is to build a portable array frame that you can unload from the camper and string out to a nearby sunny spot. Alternatively, invest in the biggest alternator your camper hauler can support, and charge the batteries on-route, utilizing the full batteries upon arrival.

 

[lido]

Slow down and first come up with a number of watthours you expect to consume in a day. My gut feeling is that only 600W of solar will be inadequate. Will the panels be mounted flat on the roof of the camper? If yes, I'd de-rate them to only 60% because of the less than optimal angle to the sun. So, 600W is never likely to put out more than about 360W in the real-world. Not enough to run the air-conditioner.

It's fundamental conflict of interest when going camping in the summer. You want to park the camping the the shade so it stays cool. You want to park it in full sun to take advantage of full sun. They are mutually exclusive. One option is to build a portable array frame that you can unload from the camper and string out to a nearby sunny spot. Alternatively, invest in the biggest alternator your camper hauler can support, and charge the batteries on-route, utilizing the full batteries upon arrival.

I should have mentioned that it is not the end of the world if these do not charge the battery to full in 1 day or even 2.
right now it is a starter system that when it is parked in my driveway it will charge the battery during the week so they are ready for weekend camping.

Your right about the conflict parking in shade and full sun. since it is a small camper its easy to move around and usually I am in full sun because during the day we are out Off Roading in the jeep or on a ATV. that's why I say we don't have the AC running much, maybe a hour or two to cool down.

the panels may be mounted so they can be angled towards the sun in the morning, then I will lay them flat during the day before heading to the trails. I put the biggest panels my roof would support just so it will provide as much charging during the peak day as possible just to help boost the battery back up for the evening and night.

so right now this is the start of a solar build until we can go camping for a weekend and see the exact amount we use. I do think between a 300Ah battery and a 2Kw bluetti I should have a good amount however if not I would probably add another 300Ah battery into the mix.

Am I at least correct with my numbers, those panels would end up being 33 amps and 18v?
so they would need to be in series to charge the controller or bluetti?

 

[MichaelK]

There is a very long legacy of dead solar batteries because they were charged at too low a rate. This is less of an issue with lithium, but I still attempt to admonish people to really attempt to maximize whatever solar they can.

How much are you paying for those Newpowa panels? There's a price premium you pay for sticking with 12V, and it make little economic sense to buy multiple 12V panels when trying to raise the voltage. As long as you are using an MPPT controller, you are only limited to the max voltage the controller can handle.

Can you provide some specs on what controller you actually have? The problem is that MPPT is so popular now, that dishonest sellers are now marketing fake MPPT controllers. Basically a cheapo PWM controller with MPPT logo on it.

Take a look for 72-cell panels in your local area on Craigslist or Facebook Marketplace. You are likely to find stuff in the 2-4W/$ range. A 72-cell panel will be putting out ~37.5V, so you could parallel that to two of your Newpowa panels wired in series.

 

[lido]

There is a very long legacy of dead solar batteries because they were charged at too low a rate. This is less of an issue with lithium, but I still attempt to admonish people to really attempt to maximize whatever solar they can.

How much are you paying for those Newpowa panels? There's a price premium you pay for sticking with 12V, and it make little economic sense to buy multiple 12V panels when trying to raise the voltage. As long as you are using an MPPT controller, you are only limited to the max voltage the controller can handle.

Can you provide some specs on what controller you actually have? The problem is that MPPT is so popular now, that dishonest sellers are now marketing fake MPPT controllers. Basically a cheapo PWM controller with MPPT logo on it.

Take a look for 72-cell panels in your local area on Craigslist or Facebook Marketplace. You are likely to find stuff in the 2-4W/$ range. A 72-cell panel will be putting out ~37.5V, so you could parallel that to two of your Newpowa panels wired in series.

I do not have a controller yet because I didn't know the amps I would need.
I think the controller I want would be bougeRV sunflower 60A mppt
but that's if I do parallel. If I do series I could use a bougeRV sunflower 30A. right?

also I only have 1 newpowa 200 watt solar panel right now the specs are in the first post. so I could use 2 other panels like from BougeRv or I thought 2 of these could work better.

https://a.co/d/d5yG5c1

 

[MichaelK]

Looking at that Newpowa panel, you are getting ~1.2W/$. Just making a quick search in your state, I found this....

You always get the best deals with cash and carry pricing, and I myself have personally found better quality panels than the ones I purchased online. Doing the math, you'd be getting almost 2.6W/$, more than double the watts for what you are paying for the Newpowa. You'll have to figure out though whether or not this panel will fit on your roof.

Here's another choice....

These are a bit scarier because the seller mentions they have been through a grass fire. Actually, I have these same panels, which I bough through a local seller in Santa Paula California. I think the longevity estimate is a bit low. I've installed these same grass-fire panels in my own system, and they are among the highest quality panels I've purchased. Since these panels are a different form-factor, you might be able to squeeze more or less on your roof. You have to figure that out. Just bring a voltmeter with you, and test any panel you purchase, no matter what the assurances are. When testing with a meter, look at numbers within 10% of the Voc, not the Vmp.

Even with 600W of panels on the roof, with 60% de-rating, the 30A controller is likely to be OK. If you happen to park on a steep South-facing slope while driving to your camping spot, you might likely go over 60%, but the controller will just clip off the extra amps.