The Trinity portable wind turbine will charge your gadgets on the go.

With the amount of sun you would get in New Mexico, direct solar thermal collectors make a lot sense, though in your case there is also an argument that can be made for powering a standard water heater (or heat pump water heater for that matter) with your PV panels. That way when there is no requirement for water heating, your system will still produce, as any power collected can either charge batteries or be fed back into the grid for credit. Since you already have a Solar PV system and the infrastructure in place, I think that is certainly worth looking into.  

If you do go that route, you could also consider getting a water heater that runs off DC, that way there would be no loss from the inverter. 

If you do decide on a thermal solar collector in the end, we do like that Vitosol Solar Thermal Panel from Viessmann. Overheating is the main cause of system failures, and they have developed an excellent solution to that problem.  

As for the SANCO2 Heat pump water heater, that is a fantastic piece of equipment, we looked into it a while ago but the price was still a bit prohibitive in our opinion, however, that may just have been Canadian pricing, and it was over a year ago so maybe it has come down. I've contacted the company to see if they offer it with DC, nothing back yet but I will update this when I find out. 

Our recommendations to everyone building a home is for the same, aim for energy efficiency, durability, safe indoor air quality and responsible material choices etc. I would point you to our guide pages to search by category or keyword -

Green building guide for high performance construction techniques

On top of that, we would suggest you take extra time on resilient home design. Since you won’t be there a lot of the time, try to foresee any issues your home may face and add design features to deal with them passively.

Here is a short list of measures you might want to consider that will help protect your home while you are away for long periods, and we have included as many relevant links as we can think of:

Choose a suitable lot to build a home with consideration put towards soil quality, water tables, emergency service access, and close enough to a community so you could have someone on call that can attend to your home regularly.  

Super-insulated homes such as passive house, and designing a home for passive solar heat collection will keep your energy costs at a minimum and also help it stay warm in the event of power failures.

When you suggest a basement, my first thought would be to avoid that and stay above grade. Building a basement is typically a more expensive way to build, and even if you take measures to protect it against flooding, you will still be at risk. A slab on grade house on high ground will safeguard your home against extreme weather events in a changing climate.  

If you do choose to go with a basement, please see our guide to durable and healthy basement construction, and take extra durability measures such as installing a sump pump, possibly a second one depending on water tables, and even a battery backup.

Choose durable roofing materials to protect against high winds, such as a professionally installed and well-fastened metal roof, or a living green roof. Asphalt shingles are the least durable and are susceptible to damage from wind and hail.

Smart homes and home monitoring with devices– control the systems of your home remotely, and monitor for intruders, temperature swings, and get smart phone notices for leaks from basements and or appliances.

We make no secret of the fact that we prefer slab on grade homes over basements, and particularly in your situation. Aside from what we mention above, it’s great to have a retirement home on a single level so you can avoid the need to negotiate stairs if you have mobility issues in the future. That said, we also have information on downsizing and home design for seniors, that you may want to consider now for when your travelling days end.

And to address the issue of cost – yes, you will put more money into a durable and efficient home, but they pay for themselves in the long run. As you plan to stay in this for the long term, we truly believe that the added investment for a greener home will pay off. The best way to keep costs down is to keep the size down and the design simple, so take time to consider how big a home you really need.