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Yes--You are correct "under normal conditions" you could "scale" the wiring for the actual current flow...

HOWEVER

Say there was a short circuit in the "1A" string... The other strings would fee >4 amps into the "1A" string you designed--And start a fire in the shorted "1A" string.

This is back to the old parallel (or series/parallel) connected solar array. With only two (or one) string of panels, a short circuit anywhere in the system will only pull 1x current.

If you have (for example) 3 parallel sets of panels (strings), then the two panels could feed 2x current into the 1 shorted panel. That is why we use "combiner boxes" that have a fuse/breaker per string...

https://www.solar-electric.com/search/?q=combiner+box

For example, say each panel can output 9 amps... And the panels have a requirement for a 15 amp series protection fuse. Then if there is a short circuit, the 2x 9 amp panels in parallel for 18 amps total will trip the 15 amp series protection breaker and help reduce the chance of a wiring/panel fire.

This is especially critical for larger arrays with >>3 parallel strings of panels.

There are lots of ways to start fires with off grid power systems... Loose connections, not using circuit breakers, something metal falls on a battery bank, a genset fuel line comes loose and sprays gasoline on the genset, "boiling" batteries dry/over charging/etc. ....

You really need to do everything "correctly" to avoid the more common sources of fire.

Looking at your system and doing a "fault analysis" (what could happen, and making sure that nothing really bad can occur) and failure analysis (see what did happen and make sure it does not happen again)--It is why the NEC and various other codes are so big. They are there to protect everyone by having standards of how things are done. Both to prevent failures (like fire), and to ensure that the next folks that work on/add to the existing system know how the first system was installed (per code) and their repairs/additions will also be safe.

Anytime you deviate from "Code"--You better have a very good reason for doing that... Or just don't do it in the first place--There is probably a reason that code required that in the first place.

-Bill

If you are living in the van full time (vs weekend usage)--The typical starting point for system design is 2 days of storage and 50% discharge... And at least 10% to 13% rate of charge.

Regarding panels--If you have "crystalline" type panels--There is probably no reason to change them out for a "better" panel (you may get 10-20% more harvest--Not much).

One thing that can increase harvest a lot--Especially in winter... Here is the amount of sun you can collect in Austin Texas, with an array mounted flat to roof (i.e., fixed roof mount on van), vs tilting to 45 degrees from vertical (tilt to collect more winter sun):
http://www.solarelectricityhandbook.com/solar-irradiance.html

First flat to roof:

Austin
Average Solar Insolation figures

Measured in kWh/m2/day onto a horizontal surface:

Jan	Feb	Mar	Apr	May	Jun
2.83	3.41	4.40	5.25	5.62	6.36
Jul	Aug	Sep	Oct	Nov	Dec
6.56	5.94	4.97	4.05	3.07	2.63

And then tilted to 45 Degrees for Winter Harvest:

Austin
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 45° angle:
(Optimal winter settings)

Jan	Feb	Mar	Apr	May	Jun
4.03	4.25	4.74	4.89	4.61	4.88
Jul	Aug	Sep	Oct	Nov	Dec
5.12	5.18	5.08	4.90	4.25	3.91

And best year round average harvest:

Austin
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 60° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
3.82	4.18	4.86	5.27	5.19	5.65
Jul	Aug	Sep	Oct	Nov	Dec
5.90	5.72	5.31	4.87	4.07	3.67

In general, you can probably collect more winter harvest if you can tilt your array to south than getting more efficient panels (2.83 hours of sun January flat; 4.03 hours of sun for January at 45 degrees)...

Lets say you can tilt the array to 60 degrees from vertical (or 30 degrees from horizontal) and look at January:

• 2.83 hours of sun per day (Jan flat) * 0.52 off grid AC system eff * 200 Watt array = 294 WH per Jan @ flat day
• 3.82 hours of sun per day (Jan @ 60 degrees) * 0.52 off grid AC system eff * 200 Watt array = 397 WH per Jan @ 60d Vert

For a full time off grid system--Suggest that the battery bank support 2 days of power usage (2 days of bad weather) and 50% max planned discharge (for longer battery bank/emergency reserve):

• 397 WH per day * 1/0.85 AC inverter eff * 2 days storage * 0.50 max discharge * 1/12 volt battery bank = 156 AH @ 12 volts "suggested" battery size (based on winter production)

Of course, if you have alternative charging (van alternator, backup genset, shore power, just use less power in winter)... You can support a larger battery bank/more charging energy.

Anyway--Suggest 5% to 13%+ rate of charge for solar... And 10%+ for full time off grid charging. A 200 Watt array will support (solar only charging):

• 200 Watts * 1/14.5 volts charging * 0.77 panel+controller derate * 1/0.05 rate of charge = 212 AH battery @ 12 volts "max"
• 200 Watts * 1/14.5 volts charging * 0.77 panel+controller derate * 1/0.10 rate of charge = 106 AH battery @ 12 volts "nominal"
• 200 Watts * 1/14.5 volts charging * 0.77 panel+controller derate * 1/0.13 rate of charge = 82 AH battery @ 12 volts "minimum

Roughly, I would be suggesting around a 106 to 156 AH @ 12 volt battery bank with a tilting 200 Watt solar array (and no other source of charging).

Things you can do to add solar charging? Making a tilting "array" for the side of the van (fold down to side of van, or fold over roof (and existing panels to store for travel)... Put it on the driver's side (avoid side doors), or on the passenger side if you want an awning over the side door (rain/sun):

You have to figure out what the amount of energy per day you really need (most energy efficient loads you can find--I.e., tablet computer or vs small laptop vs full desktop computer), RV water pump, LED lighting, etc...

For heating--Just to give you an idea... a 1,500 Watt system with 397 WH per day (Jan tilted array):

• 397 WH per day (Jan/tilt) 1/ 1,500 Watt inverter = 0.26 hours = 15 minutes per day

If you got a diesel fuel heater (popular for vans), 1 gallon of diesel will give you the equivalent:
https://www.convertunits.com/from/gallon+[U.S.]+of+diesel+oil/to/kilowatt+hour

• 1 gallon of diesel = 40,700 WH of energy
• 40,700 WH * 0.85 heater eff = 34,595 WH of "heat"
• 34,595 WH of heat / 1,500 Watt electric heater = 23 hours of "electric heat" equivalent (on 100% of time)

Genset wise... Get a small Honda eu1000i or equivalent genset (gasoline) for backup charging/power:
https://powerequipment.honda.com/generators/models/eu1000i

• 900 Watts full output * 0.25 output (example 225 Watt load) * 6.8 hours (at 25% load) / 0.55 gallon tank = 2,782 WH per gallon of fuel
• 2,782 WH per gallon / 397 WH per day Jan/tilt harvest per day = 7 days of "winter solar equivalent" per gallon of gasoline

A small genset and a few gallons of gasoline is not the worst solution if you need more electricity than your solar system can supply (use genset to recharge battery bank and/or directly support your larger AC loads when needed).

We are talking a lot about loads... And you need something to measure them. Some examples:
https://www.amazon.com/s?k=kill-a-watt&ref=nb_sb_noss (Kill-a-Watt type meters for 120 VAC plug in appliances)
https://www.amazon.com/s?k=dc+watthour+amphour+meters&ref=nb_sb_noss (DC WH/AH meters)
https://www.amazon.com/UNI-T-UT210E-Capacitance-Multimeter-Resolution/dp/B075ZHDQFP ("good enough" AC/DC current/DMM meter)
https://www.amazon.com/gp/product/B019CY4FB4 ("better" AC/DC current/DMM meter)

The above are just suggestions... You can look through them and see what may work better for your needs. And there are lots of other options (Battery Monitor Systems) that are nice too.

I threw a lot at you... It really comes down how much electrical energy you need--And what it is worth to you (something nice/to keep you sane--Or need to make money at a remote job site). The system needs to meet your needs and expectations.

-Bill

Welcome.
  Looks like you just barely have enough solar PV to manage the batteries you have,  adding more batteries without more solar to charge them with, will fail.   You want to aim for 10-15% of the battery capacity, as your charge rate. 200ah of battery, needs at least 20A to charge with.

Panels aimed at a different direction, would need their own charge controller - unless they are the same as the existing panels.  You would really want to have some new 300w ballpark panels, and use a MPPT controller with them.

24V batteries generally need 28 - 30V available for charging, so your PV array should be rated 45-60V Vmp    Lower than 45V, the MPPT circuit may not work - check the specs for your candidate controller and don't let the Voc exceed  the input voltage of the controller.

These are the general rules of thumb I go with.   And PV panels only produce 75% of their rated power - because of aim and atmospheric losses