Toggle navigation
0
  • Sign In / Register
  • Logout
  • Home
  • Solar Kit Guide
  • My Account
  • About Us
  • Contact Us
  • Solar
  • Wireless
Solar
Wireless
Sign In
My Account
  • My Account
  • My Projects
  • Purchased Items
  • My Profile
  • My Contributions
  • My Questions
  • Settings
  • Billing
  • Addresses
  • MegaWatt Membership
  • Logout

Renvu

  • All
  • Solar
  • Wireless
ABOUT US SUPPORT
Register For Prices
Home > Newest Products: Solar > Learn > Technical Support > Products > Batteries > 

Battery Technology Selection

Battery Technology Selection Ian McCluskey 9/27/2017
The purposes of batteries in solar include providing safe, reliable chemical energy storage for night time and cloudy weather, voltage stabilization, surge currents and portable power among others.

Battery Types

  • Battery Construction - Anodes (negative) and cathodes (positive) in cells wired in series, resting in an electrolyte

    • Positive and negative terminals - energy flows in either direction depending if charging or discharging

    • Anode, cathode and electrolyte chemistry vary

  • Efficiency = Power out / Power in

    • Lead acid - 80-85% ; Li-ion - 90-95%

  • Depth of Discharge vs State of Charge - DoD and SoC are inverse measurements of the remaining energy in a battery relative to its capacity

  • Capacity - Lead Acid depends on rate of discharge, the “C/h” rate

    • Available Power (for charging and more importantly discharging) - depends on internal resistance of battery.  

      • Lead acid - discharge is usually rated at C/20, charge at C/3-C/7

        • Eg. A 1050 Ah with C/5 charging will absorb 210 Ah per hour

      • Li-ion - charge rate is usualy C/1 - C/0.5

        • Eg. 1050 Ah with C/0.5 will absorb 1050 Ah in 0.5 hours

    • Power Rating or “Max Power” - Product of max discharge amps and system voltage

Lead Acid Batteries

  • Flooded - Each cell is 2-volts * nominal *, least expensive

    • One vent cap per cell, eg. 3 vent caps = 6VDC

      • Cells connected in series with terminals on opposite ends

    • Sizing - Reverse correlation between system capacity and ideal individual battery voltage

    • Chemistry -  Full discharge damages battery with sulfation and allows it to freeze * DO NOT PUT BATTERIES IN AREA THAT FREEZES *

    • Flooded require distilled water, but can overcharge harder to desulfate the electrodes! Good for standalone

    • For example see TROJAN T105-RE Deep-Cycle Battery

  • Valve-regulated - AKA Absorbed Glass Mat (AGM) or Gel, are more expensive

    • No removable vent caps, just valves to regulate pressure

    • Better for back-up systems / less maintenance; shorter lifetime (less cycles)

      • Sensitive to overcharging and high temperatures

    • No-spill, some can be installed on side

    • AGM - Electrolyte absorbed into a fiberglass mat

      • Very common, side-install into rack with integrated busbars for industrial applications.

      • For example see Trojan Solar AGM 12V 205AH at 20 HR Deep Cycle Battery

    • Gel - Can be more expensive, better for deep discharges

  • Capacity - Measured in Amp-hours (Ah) or watt-hours (Wh)

    • Influenced by temp and discharge rate (C/h)

  • Voltage - Affected by state, always measure at resting



Wondering about
Lithium ion batteries? Since they are much more sensitive than lead-acid, that is a good place to start the conversation about charge controllers. Read on to Charge Controllers and Lithium Batteries !

To read the Full Battery Series:
1. Battery-based System Load Analysis
2. Battery-based System Types and Modes of Operation
3. Battery Technology Selection
4. Charge Controllers and Lithium Batteries
5. Battery-based System Electrical Integration
6. Battery-based System Commissioning


Downloads

Comments

Your comment will appear once it has been approved by the RENVU team.

Add A Comment

You must Login / Register to post a comment.

Related Items

  • Home
  • Terms & Conditions
  • Privacy Policy
  • Payment Methods
  • Shipping Policy
  • Contact Us
  • Facebook
  • Twitter
  • LinkedIn
  • YouTube

Copyright © 2018 Renvu - All Rights Reserved