Lowtech Graph lists low-tech options for every need of a home. Here you can compare them, find tutorials to build them, and link them together into a circular system. Why low-tech?
Dual-bus wiring (DC essentials + AC general)
Passive
One of 4 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
Two separate electrical circuits in the house: one running essentials such as lights and a fridge straight from batteries, the other running everything else through an inverter. If the inverter fails, the simple essentials circuit keeps working. The things that matter most stay on.
Build it
No build tutorial recorded yet.
Cost
Medium
Upkeep
None
Skill to build
Intermediate
Lifespan
Wiring itself: 30-50+ years; breakers/switches at bus junctions follow standard electrical-hardware cycles (20-30 years)
Embodied carbon
Low
Space / material use
Low
Output timing
On-demand/controllable
Skill to repair
Intermediate
Regulation (FR example)
Fixed electrical installations must meet NF C 15-100, and a Consuel certificate is required before a new connection is energised. Grid-connected generation requires an Enedis connection agreement.
Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.
Dual-bus wiring (DC essentials + AC general) (This page) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: None · Change to daily life: None · Works without the grid: Yes Choose it if you want lights and the fridge to keep working even if the inverter fails.
Inverter (DC to AC) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Specialist · Upkeep: Light · Change to daily life: None · Works without the grid: No Choose it if you want a solar system to run ordinary sockets and appliances.
Direct solar power (battery-free direct-PV supply) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Intermediate · Upkeep: None · Change to daily life: Daily · Works without the grid: Yes Choose it if some tasks can wait for the sun, such as pumping or heating water, and you want no battery to buy.
Solar power diverter / router (surplus-PV to resistive load) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: None · Change to daily life: None · Works without the grid: Yes Choose it if you want your solar surplus to heat water instead of being given away.
Sources
General electrical-wiring industry durability consensus
Limitations of this page
We don’t list sizing or quantities, as the yield of each technique depends on the quality of its build. The catalogue compares options but doesn’t dimension them. Regulatory notes are indicative, with a French example, and need to be confirmed locally.