Calculating a good charge current for 3s156p 18650
You "could" charge at 2150mA * 156p = 335.4A  or using CC to  4.2V then off at 10% of CC, but this is not wise over the lifetime of the battery as cells fail the rest must take up the current which accelerates failure of the while pack. Even with this being   2x nominal current of 167.7A only saves 0.5hr/3hr or 16% of the time.

It is wise to use nominal current and this power represents 168A*4.2V*3 = 2.1kW.

A 140W Solar Charger is only 6.6% of your storage capacity and there can be significant charging losses in the battery and charger. This might support 1kWh per day of use assuming > 8 hrs of full sun per day with solar tracking.

Choices of charger and Solar power source require that you define your Solarity index and Energy consumption patterns max/day, avg per week and budget for  a power source + charger.  

The van's engine alternator might be a good source if avail. with 4.2V*3 = 12.6V from 14.2V using a LiPo regulator with balancer.  Dodge Van alternators can be upgraded to 180A I believe and if there is room to add a 2nd alternator, it can be modded to act as an exclusive LiPo charger.

p.s.

I assume you have the skills to make this safe and reliable. Otherwise, better check your Van insurance for fire from DIY battery failures.

Multiple Thermal sensing is critical with intelligent power management.