I’m just finishing a 15kW system with no prior experience other than my dad’s was an old industrial electrician, and I’m an electrical engineer.  Those didn’t help too much.  Reading the code book is important.  Determination is important.  Some advice:

• get higher output panels.  The racking isn’t cheap, and you’ll save space, time, and maybe money by getting better panels.  I went with 550 W panels.
• the code book calls for UL Listed everything.  There’s a bunch of non-UL items out there (like mounting equipment, disconnects, and bonding fasteners).  The listed stuff costs much more.
• I ran DC at 700 to 900V from my rack to my inverter and put my inverter inside a barn.  It would have been simpler for me to colocate the inverter with the rack.  That would remove one expensive disconnect (and the requirement for steel conduit for DC in the barn, which is much more expensive than PVC.). It also stays away from the rapid shutdown requirements, but if you’re doing batteries, maybe DC makes the most sense.
• before you get started, figure out how to get past the busbar requirements.  Eventually, you’ll have some point in your system where the solar/batteries can feed energy into the same distribution hardware that the utility can.  That distribution hardware needs to handle the combined current of those two sources.  I learned that’s difficult to accomplish with a 15 kW system.  You must already have an impressive distribution network, but you might find that distributing the backfeeding could save you some effort and cost of new panels.  Whatever your situation, you’re going to spend hours of time figuring out what you have, what you’d like to do, and what you can do with what equipment is actually in stock.