Battery Backup

Modern solar systems can now include battery backup. If you desire more than a simple grid-tied solar system, MUST SOLAR offers the following options:

A) Grid-tied solar systems that also include battery backup
B) Battery backup power for select electrical outlets or appliances
C) Battery backup power for entire building
D) Use of battery backup at select time of the day (TOU)
E) Use of battery power to minimize surge load on utility (Demand Reduction)

Locations with unreliable power may be well served by an energy storage system that includes battery backup and solar power. Proper selection of equipment can support both grid-tied and battery back-up functions. SunnyCal solar can design and install a systems that can even work completely off-the-grid, where no utility power is economically available. Danger of losing power in the event of fire emergency or natural disaster is greatly reduced.

Increasing utility charges for energy use during peak times (Time of Use) can be eliminated by active energy management.


Residential Energy Storage……… Industrial Strength Design

  • Models offer 120/240 Vac split phase with up to 75% phase imbalance, allowing direct connection to the home’s multi-branch wiring. 240 Vac operation ensures well pumps will operate with battery backup.
  • Simple to parallel inverters for 12 or 18 kW systems.
  • Inverters have network and sync ports built in, and communicate seamlessly to synchronize invert and charge modes.
  • All models are regulatory approved and CEC listed for both off-grid and grid interactive applications.
  • 4000W, 5500W and 6800W are approved for grid-tie use and can support complete off-grid also.
  • Dual AC inputs make it simple to use with generators in hybrid grid-tie, or with generator/micro hydro or dual genset applications.

Efficiency is what saves you money

Highest charge current and efficiency available

  • 100 amps @ 89% efficiency
  • Highest inverter efficiency in inverter and “sell” mode
  • 95% efficient off-grid mode; 92.5% CEC efficient grid tie mode
  • Best-in-class surge overload performance

32 kW of real power output (not just current) to start loads.

Voltage regulation while surging

Complete system solution using modular components

  • The system is comprised of manageable building blocks; Inverter/Chargers, Solar Charge Controller, Power Distribution Panel, Conduit box, Automatic Generator Start module, and System Control Panel.
  • All system components are networked, and remote internet information.
  • Inverter/Chargers, Solar Charge Controllers, Automatic Generator Start modules, and System Control Panels communicate with each other out of the box.


When new construction of an off-grid home is underway, the first structure to be built is often the solar Power House. This enable a solar system to provide electrical power for temporary dwellings and construction equipment.

battery + inverter

The Power House is custom built for SunnyCal by Tuffshed Inc. These buildings are pre-ordered for specific colors and layout, and can be installed in one day.


The Power House provides reinforced steel floor on the battery room, a lockable entry door for security, and floor and veiling vents for flow-thru ventilation.

The equipment room is isolated from battery fumes, and has ample room for wall-mounted inverters and charge controllers. The power house can be painted with a broad selection of colors, with coordinated roof shingle colors.

Electrical power outlets, switches and lights are included with every powerhouse. Motion detecting lights and outside GFCI outlets are options.

Lead Acid Batteries Still the standard after all these years, the wet cell lead acid batteries remain the workhorse of many solar electric systems. Modern lead acid battery banks have a 5 year warranty period, with much longer life expectation if not cycled to below 50% depth of discharge. Advances in plate design using circular rods to increase the surface area provide higher energy capacity than past flat-plate design.


Important considerations when deciding on lead acid batteries are:

A) Venting of flammable gases out of battery storage space

B) Weight of the battery (heavy banks require a fork lift for transport)

C) The need for maintenance of electrolyte level (water). Typically checked monthly.


Most large battery banks for solar backup are configured as 48V banks. The inverter must be selected to match the battery voltage. Inverter efficiency increases with higher battery voltages. Additionally, the size of battery cables is smaller for higher voltage batteries. See the battery charger table for proper inverter settings.