An off-grid solar system (off-the-grid, standalone) is the obvious alternative to one that is grid-tied. ... To ensure access to electricity at all times, off-grid solar systems require battery storage and a backup generator (if you live off-the-grid).
Solar thermal technologies capture the heat energy from the sun and use it for heating and/or the production of electricity. This is different from photovoltaic solar panels, which directly convert the sun's radiation to electricity.
Roof mounts are less expensive because they use your existing roof structure as a foundation. They also take up less room on your property. Ground mounts take up more space, but they’re easier to access for installation and repair. They also give you greater control over the orientation of your array to maximize production.