Tim,
What created this idea was having to leave work, go home fire up the generator, then go back to work, assuming the text from Duke came through. It was the unplanned outages, the out of nowhere outages, that seem more frequent. Also, the on off flickering, then the restart, followed by the overflow of the skimmer due to height changes in the sump, and no delay on the skimmer start. See, to me, it's all those little things adding up that compels me to create redundancy, emergency UPS/constant power, and above all, getting old, and planning on it getting more and more challenging.
As far as Solar goes, this is something I am about to dig deeper into over the winter, when the garden stalls and I have to have other learning interests, lol... From my understanding, I think the Delta2 peaks at 500w inbound from solar. I have to recheck. Now, being able to collect that much during the day with a 400watt panel for example would be unreasonable. However, not for the essentials, you could easily run what I need for "reef essentials" on solar, with the Delta2, given it would essentially recharge the battery from what depleted during that 24 hour interval. That said, a return pump, on the River, with a 200watt solar input, likely would easily handle most "return pump" applications, especially in FL, given you have a good enough angle to capture sunlight.
Where it gets interesting is the app controlability of these batteries. You can actually set the battery to prioritize solar over ac, giving you the ability to save on electricity if you choose a more permanent style of solar capture. These batteries also accept off car battery as well. This gives a multitude of options, and leads me to why I am considering starting a delivery service option for corals. Still kind of in the process of figuring it out, but I could easily use one of my Delta2 to transport live corals, keeping the climate exactly where I wanted, with wave movement, and led lighting during transport. I have a design to use a sump to avoid overflow spillage during transport as well, this way I could use carbon in the bucket sump design, as well as biomedia. I am less than a month away from being able to go live... If I did this, then I could set up delivery in the state of FL, and if enough orders consolidated, travel periodically and deliver goodies... More to come on that

Maybe you could be my first customer, lol...