School Me on Solar Panels

[TurnThePage]

I recent started a thread about lifepo4 battery configurations, 12v/24v/etc. I think I'm settling on four 230 AH batteries, and will likely keep them in a 12v config.

Now I want to figure out the solar. I am mounting the panels in a permanent position on the roof with no adjusting for best sun.
I see lots of systems where they are very close to the roof and wonder about that. Panels get hot. My intention is to run tracks the length of the roof and mount on them, maybe keeping the panels 4-6 inches off the roof. That will provide good ventilation and even shade for the RV. It will also reduce shadows on the panels from other stuff on the roof.

Now my questions:

I'm not familiar with current wiring methodology. Are they all the same now? I hear people mention MC4 connectors. Is that the standard? Do I need to worry about that or will all the hardware be compatible right out of the box?

What about the panels themselves? I've understood that monocrystalline is superior to poly for RV use. Is that still the case? It sounds like most panels are manufactured with shade tolerant diodes built in now. What other considerations are there?

[RLS7201]

I suggest 24 volt panels. That gives you half the amperage and better voltage for the MPPT controller to work with. Some times the 24 volt panels are less expensive.

Richard

[2oldman]

TurnThePage wrote:
I see a huge variety of shapes and sizes out there. Do people mix and match?

In series (what I see is also being called serial) matching amps is important as the string will defer to the lowest panel's capacity. I have 3 different brands in 5 panels and they work just fine.

[CA_Traveler]

Serial panels should be the same Imp rating. Parallel the same Vmp rating.

[3_tons]

Your panels should come with MC 4 connectors (male and female), and for series, simply daisy chain them (say, + to -) together…Various gauge and length wire pairs (with + & - MC 4 connectors on their panel connect end) are available on Amazon…FWIW, there’s really no advantage to mono vs poly except that mono has a slightly smaller footprint resulting from mono’s slightly increased efficiency…Your free to mix panels (and footprints), but it’s best overall that voltage ratings remain closely similar (more critical with parallel than when in series)…Happy Harvesting 🙂

3 tons

[time2roll]

Panels are mostly a commodity. Lowest price per watt is the key factor although need to get what fits and they keep getting larger. Best to have matching panels for extracting the most power. Shipping can get expensive, look for a local surplus for pick up.

[TurnThePage]

I guess I should have mentioned that yes I'm going with a serial configuration into MPPT controller(s).

Are there preferred type/brands of panels? Are there any to stay away from? I already intend to avoid the surface mount flexible ones.

I see a huge variety of shapes and sizes out there. Do people mix and match?

[CA_Traveler]

2" spacing is adequate, mine are 6" to eliminate shade from the A/Cs. MC4 is a standard connector. Bypass diodes provide better shade tolerance for serial panels and more power than parallel panels. You'll need a MPPT controller with input voltage spec greater that the combined Voc of the serial panels.

[2oldman]

Wire in series and you won't need thick wire or a combiner box. Tilting for best sun will gain about 50% more harvest.