Took my family up to Volcano so we could see the National Park, and we were very pleased with our stay! The house is like a work of art, and in fact includes several works of art from the owner Joshua. As we'd never stayed in a modern "off-grid" home before, he told us all about the rainwater catchment, solar power, and construction techniques (pretty sure the place could withstand armegeddon!)
The house is very comfortable due to being a modern insulated home, unlike many rentals on the Big Island that are unpermitted shacks or rundown. The kitchen was amazing, big fridge, handmade concrete counter-tops, and you can socialize between the kitchen and living room while you cook. Bedrooms were stylish, brand new beds and bedding, and we kept our windows cracked at night to enjoy the cold mountain air. There is also a lot of outdoor space both covered and uncovered; we enjoyed coffee on the lanai (covered deck) in the morning talking and listening to the birds and didn't have to worry about waking the rest of the family.
We were lucky to have a relatively clear night, and the stars up there are amazing. You can literally see the milky way and we caught a few satellites and shooting stars. Bring hoodies and hot chocolate!