Exposed ends on MC4 connectors...will they deteriorate?

Just a caution... "We" are used to working on electrical wiring systems that have a single power source (such as utility power, genset, battery bank, etc.)... However, with solar, we typically have multiple power sources (parallel strings of solar panels, Battery Bank+Genset+AC inverter-charger, etc.). Multiple power source electrical wiring (such as your main DC bus) are a bit more complex/different than people first expect when trying to design "something safe".

For example, the maximum current on a common battery bus is the Battery Bank + Backup AC battery Charger + Solar Charger--So that "common point" on the bus now has the sum of three (or more) current sources (each may have a 100 amp breaker, but the bus+local wiring has 300 amps of current available).

Another gotcha is the question of grounding the Battery bank negative terminal. It turns out that most people use a single circuit breaker on each "hot" (usually positive) wire of the battery bus. It turns out, that if you do not "hard ground" the DC return (typically negative) bus to the metal of the RV, that the a pair of short circuits (say one in the negative lead in a light fixture) and a second in the positive lead to the AC inverter)--That you can burn out your wiring and start a fire in the light fixture return current path (no fuse/breaker).

People like "floating" (non-grounded) battery power systems--And for the "first short" they are fine. However, floating systems with one short are no longer floating (and most systems will run fine with one short)--Setting you up for a very hazardous set of conditions if you ever get a "second short"--In industry, floating power systems typically have double pole breakers (breaker on + and - or hot and return) to prevent such failures from happening. And on the "rare" floating power systems, they usually have some sort of method of detecting a short to ground (this is what the newer NEC codes require for solar arrays and DC power systems).

For solar, some of the "middle age" regulations are actually very dangerous--And the ground fault detection is either poorly designed (really unsafe) and/or "overly sensitive" (Arc Fault type breakers is another "problem")... Grounding and safety is a major concern with us here. And why some of the suggestions "sound cook book" (do this, don't ask why unless you like long boring technical explanations). And why the NEC has so many rules--If you follow them correctly, it prevents secondary issues/complexities from causing you grief. But it can also make a system more expensive and complex (not everyone can afford/fit $100's for heavy wiring/sets of circuit breakers).

It is a risk/reward set of decisions. We will try to keep everyone safe, but each is responsible for their choices.

-Bill