Big loads offgrid with a small battery (sidelined)
The author describes managing high-power loads like an electric kettle and toaster on an offgrid system with a small battery, using a relay to prevent the inverter from overloading. However, running a larger load (a heat pump water heater) alongside other devices causes the inverter to trip, leading the author to plan a smarter load management system using an Arduino and relays.
Background
- Joey Hess is a well-known open-source programmer (creator of git-annex, former Debian maintainer) who blogs about his off-grid life in rural Oregon.
- This post is part of his "sidelined" series, written while recovering after a serious cycling accident that left him unable to work on software.
- He lives entirely off-grid with solar panels and a relatively small lithium-iron-phosphate battery (5.5 kWh — about half the capacity of a Tesla Powerwall), which forces him to carefully manage power use.
- The blog describes a technique he calls "opportunistic loads": running high-power appliances (washer/dryer, saws, battery charger) only when solar generation exceeds what the battery can store, using real-time metrics to avoid draining the battery at night.
- This matters because it's a practical, real-world case study in energy management that contradicts the common assumption that off-grid living requires a massive, expensive battery bank. It's relevant to anyone interested in solar, resilience, or living with intermittent renewable energy.