The company I work at operates ~20 30' mobile dental units that treat patients at long term care facilities, we build our units from an empty shell into very nice trailers. We operate in ~10-12 states in various climates and all of our units are powered by noisy unreliable 13kw generators in a truckbed. We hate them, residents hate them, and everyone hates them. Having a tesla, I had the idea when the powerwall first came out to use that in our mobile units. After several emails / voicemails to Tesla went unreturned I finally got someone to call me back and they basically all but said they wouldn't even sell us one if they knew it was going in a mobile unit. (That killed that route, sadly) In the spirit of not giving up, I decided it may work out to DIY it and build our own. They don't like the idea of solar panels due to wear and tear (ever driven on AR roads?), holes in the roof, theft, etc ? Even with Solar panels we'd have to cover the whole roof to come close to making a dent, I fear. That being said, I had the idea of potentially upgrading to ~3 aftermarket high end alternators that can output 200amps at idle each. Throwing a dart at the wall I think we use ~4.5kwh depending on the time of year for ~8h, everything in the unit is 110v and nothing 220v. The other benefit here is it could be charging the batteries in transit to facilities which can be ~1-2 hours away and on the way back. I envision once I talk them into it down the road potentially having a mixture of solar panels + alternators. Long story short - I'm having trouble with the following: A. Calculating the size of the battery bank necessary. Based on my math we'd consume ~41a at 110v per hour, needing 102ah per hour at 48v or 204ah at 24v. I know with other battery types its advisable for the lifespan to not go below ~40-50%, how much should I oversize it with lithium? Our goal over time is to try and make them more energy efficient but there's not a whole lot of areas to cut as it is. B. Deciding between Lithium or other battery types. I like lithium due to size/weight savings - but we plenty of curb weight headroom to easily add 1ton or more if we had to to our units. C. Deciding where to purchase them and who might provide us with decent volume discount - we will eventually convert all 20 units plus the additional we build (~5-6 a year currently) to all battery banks. D. Deciding which inverter, charger, and batter meter/monitor we should get - we care more about reliability than price - again 4.5kw was an average but we could easily have spikes up to 8-10kw. If anyone has any insight I'd love all the advice we can get, I hope I posted in the right area.