Solar hot water: Showers heated by the sun · Alt Ordo Systems Guide

A solar water heater is a dark tank or collector behind glass that soaks up sunlight and turns it into hot water, stored for when you need it. The simplest is a black bag on a hook. The most capable is a freeze-proof loop of antifreeze, a small pump and an insulated tank. Sunlight is free and the parts are plumbing, not electronics. What goes wrong is nearly always one of three things: freezing, scalding hot water, and too little sun in winter. This guide shows how to deal with all three.

This guide helps you pick the right kind of solar water heater for your climate, size it for the hot water you really use, build a batch heater or fit a freeze-proof kit, and run it safely: no frozen pipes, no scalds, and a backup for cloudy weeks.

What's inside. 20 pages in 9 chapters (At a glance, Where it works, How it works, Size it, Parts and cost, Build it, Run it, Rules and permits, How it connects), then the sources and a notes page. 7 numbered figures drawn for this guide. You also get a worked example with a fill-in worksheet, 10 numbered steps, a year-round calendar, and a troubleshooting table.

Sourced and fact-checked. Facts and figures are cited to the 27 sources listed at the back, and the whole guide was fact-checked before release. General guidance, not engineering advice: your county and a qualified pro have the last word on your site.

Pairs with other Alt Ordo Systems Guides: Roof rainwater catchment; Water storage and off-grid plumbing; Generators, propane and fuel; Wood stoves; Off-grid solar. For your county's permits and rules, see our county and state guides.

Instant PDF download. After checkout you get a download link by email. Letter-size pages, made to read on screen or print at home.