Heating

Solar furnaces can deliver thousands of watts of heat to an incredibly small spot.  This means that you can get immense efficiencies of heat transfer, unlike traditional solar methods.

This heat can be used to create steam or hot water for radiant heating systems.  it can also be used for small smelting or casting jobs, with no fuels or exhaust fumes.

Steam power from a solar furnace can operate a steam turbine and generator, producing basic electrical power from raw sunlight, without the expense of solar cells.

Lighting

Imagine concentrating the light from a large area into a small cable and then running it inside your home or office.  Now you can replace traditional skylights, but at great advantages.

You can't take a skylight with you when you move.  But a solar furnace can be taken literally anywhere.  Solar lighting does not require large holes in your roof, it does not destroy the insulation value of your building, and intruders cannot crawl into your building through a light fiber.

Skylights are next to impossible to put in a basement, but solar lighting can be run into closets, nooks, basements, or anywhere else you need sunlight.

Power Generation

Small steam engines can be run directly from the heat of a solar furnace.  Larger steam systems can operate turbogenerators and produce electrical power and hot water all in one operation.

Cooking

Solar ovens and cooking devices can provide campers, survivalists, or disaster areas with the ability to prepare hot meals, even where there is absolutely no power grid or fuel available.  Al you need is sunlight.  You can bake bread, roast meat, or cook a pot of soup with a solar furnace system.

Water Purification

Clean drinking water is the most important resource for life.  Solar furnaces can operate distilleries for fresh water literally from mud and trash.  Remote areas and disaster scenes can be turned from nightmares into safe and survivable locations.

Emergency management teams could deploy low-cost solar furnace hardware to hurricane and flood areas, allowing disaster victims to be able to purify drinking water and maintain some basics of survival easily.