The Laney College Carpentry Department in Oakland, California built a net zero tiny house, the Wedge, in 2016 for the SMUD Net Zero Tiny House Competition
https://youtu.be/PyxJQynaC_c
That tiny house is for sale for
$55,000
https://tinyhouselistings.com/listings/oakland-ca-12-matthew-wolpe
Laney College carpenters are currently building two other prototypes tiny houses, the Pocket House, for the unhoused and homeless in Oakland
https://laney.edu/carpentry/tiny-houses/pocket-house/
The Northern Nomad is another net zero tiny home designed and built by a group of students from Carleton University in Canada as this video from 2019 shows:
Northern Nomad Tiny House
https://youtu.be/gbz35FLg9L4
http://www.thenorthernnomad.ca/
Reading Design Guidelines for a Net Zero Tiny House (https://tinyhousedesign.com/design-guidelines-for-a-net-zero-tiny-house/) and Guide to Off-Grid Tiny Houses (https://gosun.co/blogs/news/guide-to-an-off-grid-tiny-house), the core idea seems to be energy efficiency first, last, and always: the less energy you use the easier it becomes to supply it with renewables onsite.
That core idea of energy efficiency applies to all houses, not just tiny houses.
