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?
Battery bank (low-voltage DC)
Passive
One of 3 ways to meet this need. Cost, carbon, footprint and rankings are relative to other solutions for the same need, not absolute.
A bank of batteries, usually lead-acid, that stores the direct current made by solar panels, a wind turbine or a micro-hydro turbine for use when they are not producing. It keeps lights, a fridge and a pump running at night and through calm or cloudy days. Lead-acid is cheap and recyclable but heavy, and lasts longer the less deeply it is drained; lithium iron phosphate is the lighter, longer-lived alternative.
Lead-acid: 3-7 years (500-1,500 cycles); see the lithium (LiFePO4) battery bank for the alternative already in the catalogue
Embodied carbon
Medium
Space / material use
Medium
Output timing
Continuous process
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.
Battery bank (low-voltage DC) (This page) Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: High · Skill to build: Intermediate · Upkeep: Regular · Change to daily life: Occasional · Works without the grid: Yes Choose it if you want proven, affordable storage for the power you make.
Lithium (LiFePO4) battery bank with integrated BMS Can I use it? Works in a flat · No rebuilding needed What does it cost me? Upfront cost: High · Skill to build: Intermediate · Upkeep: Light · Change to daily life: None · Works without the grid: Yes Choose it if you want storage you can empty almost fully, lasting thousands of cycles in little space.
Small-scale compressed-air energy storage (CAES) 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: Occasional · Works without the grid: Yes Choose it if you want storage without batteries, with parts you can repair.
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.