DIY Manual

28 | P a g e 10-543-1 REV A
DIY Manual
BATTERIES
A battery bank can be 1/3 cost (or more) of your solar system, so battery choice is important in
terms of budget, longevity, and performance. Considerations when choosing a battery type
include cost, voltage and amp-hour capacity of the individual battery and the overall bank,
placement in or outside of the dwelling, cold temperatures, charging rates, and future expansion.
BATTERY TYPES
Flooded – Typical, wet cell battery type; lead plates suspended in electrolyte. Identifiable by
removable cell caps on top of battery.
PROs CONs
• Inexpensive • Outgasses hydrogen and oxygen
• Equalization allowed • Store fully charge to prevent sulfation
• Can add distilled water • High self-discharge rate
• Not ideal for standby use
GEL / AGM – Both are sealed battery types, sometimes called SLA – sealed lead acid, SVR – sealed
valve-regulated, or VRLA – valve-regulated lead-acid. Gel uses an electrolyte with consistency of
petroleum jelly; AGM, or absorbed glass mat, uses glass fiber material to trap the liquid
electrolyte. AGM performs better than Gel in cold temps.
PROs CONs
• No outgassing • More expensive than flooded
• Battery orientation • Usually cannot equalize
• Deeper discharge (80%) • Sensitive to over- and under-charging
• Faster charge rate • Shorter lifespan than flooded
• Ideal for standby use
Lithium - New battery chemistry, popular in electric cars and smart phones. Requires a Battery
Management System (BMS) to regulate charge amongst cells. Lithium batteries are very sensitive
to over-charging – a BMS is critically important.
PROs CONs
• Deep discharge (100%) • Most expensive
• Maintains high voltage level • Need for protection, BMS