Most of the approaches I've read about involve batteries...which is probably a good clue that having some battery in the system is not a bad idea. As you say, a battery simplifies the problem. I was hoping there was a budget non-battery inverter that could spare me from the control complexity by cleverly and nearly-instantaneously mixing utility power with the available PV power. Now I'm not so sure that's the case.
So, there definitely exists AIO that can do Solar-Utility mode (and you can look for a batteryless). But these by default will not blend utility with inverter. That is not allowed without either being naughty or with an interconnection agreement. These switch between grid and load in an all-or-nothing fashion. I don't think you can use a double conversion setup either to blend it without writing custom code. (double conversion being taking AC, converting it to DC, and then putting the on the same DC bus as the MPPT and modulating the power share as appropriate in real time. I have not seen this architecture, presumably b/c if you have the money to pay for this much hardware, you also have the money to buy an interconnection agreement and appropriate tier AC blending inverter. Or because the demand is so low nobody deigns to implement & sell it). AC blending is an advanced feature, you need a multiplus or better. $1500 for a 230V EU version that is not legal to grid connect in the US, but is capable of AC load sharing. I don't know if it's capable of battery-less operation (IE, the AC blending things are niche, and battery-less are a niche, the combination can be a unicorn).
I would be willing to consider a small amount of battery in the short term.
On r/evcharging, I remember talking to someone that used a pretty small buffer battery. For a simple EVSE with static charging rate, you would size the inverter to the discharge power of the battery, and the MPPT+solar to probably 1.5-2x the discharge power. And the inverter matched to the EVSE charge rate. This way if there is plenty of sun the MPPT has enough power to satisfy the buffer battery and the EV. (You should go look for other posts or endlessphere posts for someone who has actually implemented it, vs shooting from the hip).
24V would be a good choice for ~3kW charging rate, in the sense that you can scale down the system better than 48V (unless smaller 48V batteries from reputable companies are readily available now).
Dynamic direct from solar charging feels more like an undergrad or masters capstone project in complexity (3-6 months of work of real development). I would imagine they would flex on their classmates with going with as small of a buffer battery as possible, without any resetting.
- Inverters. I'm aware of a handful of popular inverters, like the 6000XP, which would likely serve the purpose I have in mind. But even there I don't have a great handle on everything. For example, I assumed that the 6000XP would seamlessly combine utility power and PV power, but that does not appear to be the case.
It won't because it's an AIO off grid inverter. It's not allowed to blend in the AC domain. And as said earlier blending in the DC domain is not common.
- If I have a battery, will something like the 6000XP be able to seamlessly prioritize PV input going to the load, and supplement with battery when needed/as needed? Or will my EVSE draw from the battery, and the 6000XP will charge from the battery with solar as it's available? Or does it even matter?
This is called Solar Battery priority mode. It is a standard AIO feature. If you want more intuition you can look for one of the power architecture schematics posted here and get confidence that this is doable. The way it would work is, the DC from the MPPT and battery will eventually converge (potentially after some voltage conversion steps) at the input to the inverter.
- The nuts-and-bolts part of a solar install: the appropriate type of wire to use in different places (I think I'm OK on the PV wire side), what type of conduit to use, and how to get wires from outside my garage to inside of my garage where the inverter would probably live. Do I mount a combiner box on the outside of my garage, and have the wires enter the garage from a hole in the back of the combiner box? Or do I run a conduit from outside up through a hole in the soffit, then down to a combiner box (or directly to the inverter) inside the garage? Or would the inverter prefer to live in my basement where the temperature and humidity are more steady? If it's in my basement, how do I run wire/conduit through my basement foundation wall?- Grounding requirements, as I mentioned before. You said it's pretty simple, but I read at least one long and confusing thread on this forum about it, and afterward I felt even less confident that I understood things.- In the event I get something other than a 6000XP, it seems likely I'll have to add breakers/disconnects/fuses, and I'd have to educate myself on all those things. One of the reasons the 6000XP is appealing to me is because all of that stuff is integrated, and I don't have to source a bunch of extra pieces and figure out a safe and not-ugly way to mount everything.
These things are all pretty well understood. It's probably easier for people if you give the questions to them pictorially with photos rather than wall of text.
It's probably easier to force yourself to pick a feasible/safe option and then make iterative changes on it vs having the entire set of free parameters floating around driving yourself nuts.
It's probably easier for people to engage if you force yourself to simplify the description and parameter space. I know, it's hard, my first few posts here were walls of text with some dense analysis.
For some of those construction questions, you can make a separate thread here or on an electrical DIY forum, maybe even simplified to a toy example, to get ideas on how to make a particular kind of conduit run work. This is ofc subject to going down a dumb path in the overall project plan because of XY problem, but at least you make it easy for respondents to participate and you learn something.
The inverter/battery is just wear item / entertainment stuff to me. IMO the $1500 +$800 cost of a 6000XP and buffer battery is in the noise of grand scheme of my edutainment toys, as long as it's safe and doesn't explode, I don't care where it is installed. The LFP battery certainly can light up. For some people on this forum, $5K, $10K are nbd for this.
For grounding, I dunno. You have to figure out your learning style and capability of filtering out technical nonsense (of which there is a lot in grounding) while you don't know much. One valid learning style is finding a trustworthy sunbae to just tell you the way it is. There's much more complex technical stuff I've had to master or pretend to understand as a practicing (non-electrical) engineer.
There are ways to mitigate messed up ground bonding (EG add output GFCI and either accept the potential for a problem in the portion of the system before the GFCI, or somehow "double insulate" it in an electrical safety and fire safety sense). For me, after exploring some bad ideas / hacks around it, I understand the correct way better.