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?
Direct solar power (battery-free direct-PV supply)
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.
What your site needs
None (pairs with a PV array).
Solar panels wired straight to devices, with no battery or inverter in between. Things run while the sun shines, so tasks that can wait, such as pumping water, heating water or charging, are done then. It avoids the cost and losses of batteries, but gives no power at night.
Wiring and controllers 20-50 years; no battery to replace, which is the approach's central advantage.
Embodied carbon
Low
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.
Direct solar power (battery-free direct-PV supply) (This page) 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.
Dual-bus wiring (DC essentials + AC general) 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.
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.
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.