Battery Storage Buyer's Guide for Residential Installers: Sizing, Warranties, and Disclosures

By REA Editorial Team · Published 2026-08-06 · Whitepaper

A practical guide to selecting, sizing, and honestly representing residential battery systems, with a warranty comparison framework and a customer-disclosure checklist.

Battery attach rates continue to climb, and so do post-install disputes about what a battery was supposed to do. This guide gives installers a structured way to choose products, size systems for the customer's actual goal, and set expectations that survive the first outage.

## Contents

Part 1 distinguishes the three jobs a residential battery can do (backup, bill management under time-of-use rates, and grid services) and explains why a system sized for one is often wrong for another. Part 2 walks through a sizing method that starts from critical loads and outage duration rather than from a product's nameplate. Part 3 compares warranty structures: cycle-based, throughput-based, and calendar-based terms, and what "end of warranty capacity" means for the customer. Part 4 covers safety and siting requirements. Part 5 provides the customer-disclosure checklist REA recommends for every storage sale, including backup limitations, degradation, and software dependencies.

## Why REA published it

Battery claims are now the fastest-growing category in the complaints REA reviews. Most are not about equipment failure; they are about a mismatch between what was promised and what the system was designed to do. Clear sizing and disclosure fix that.

Download the PDF for the full guide, worksheets, and checklist.

• storage
• batteries
• warranties