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?
Solar PV array
Passive
One of 8 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
What your site needs
Unobstructed south-facing roof or ground-mount area
Solar panels on the roof or the ground that turn sunlight into electricity. The panels produce direct current, which can power suitable devices straight away or be converted for ordinary sockets. They make free electricity every sunny day, with no moving parts and no fuel.
25-35 years; manufacturers commonly warrant 80% output retention at 25 years
Embodied carbon
Medium
Space / material use
Low
Output timing
Weather/time-dependent
Skill to repair
Intermediate
Regulation (FR example)
Roof-mounted panels on an existing building require a prior declaration (declaration prealable) at the mairie; stricter rules apply within a protected or heritage perimeter. Grid connection additionally requires an Enedis agreement and Consuel certification.
Levels are relative to the other options for this need, not absolute. Fewer dots is lighter.
Solar PV array (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: Light · Change to daily life: None · Works without the grid: Yes Choose it if you have a sunny roof or patch of ground and want free electricity with no moving parts.
Small wind turbine Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Regular · Change to daily life: None · Works without the grid: Yes Choose it if your site has steady wind and you want power at night and in winter.
Micro-hydro turbine Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: Intermediate · Upkeep: Regular · Change to daily life: None · Works without the grid: Yes Choose it if water flows all year on or next to your land and you want power day and night.
Mains electricity Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Specialist · Upkeep: None · Change to daily life: None · Works without the grid: No Choose it if the grid reaches you and you want the most reliable supply in normal times.
Pedal / hand-crank generator Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Basic · Upkeep: Light · Change to daily life: Daily · Works without the grid: Yes Choose it if you want a little emergency power, for a phone, a light or a radio, from your own muscles.
Water motor for direct mechanical drive Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: Intermediate · Upkeep: Regular · Change to daily life: Occasional · Works without the grid: Yes Choose it if you have a stream and want it to drive a pump, a mill or a tool directly, with no electronics.
Electric motor (mains or battery driven) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Low · Skill to build: None · Upkeep: None · Change to daily life: None · Works without the grid: No Choose it if you want quiet, controllable drive at the flick of a switch.
Small petrol or diesel engine (direct drive) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: Medium · Skill to build: None · Upkeep: Heavy · Change to daily life: Occasional · Works without the grid: No Choose it if you need heavy work done far from any wiring, even when the grid is down.
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.