Concord Solar + Battery Project: Design, Backup & Monitoring
Updated: 4 days ago
How a Concord homeowner’s goals shaped the equipment, backup design, and installation details.
For this Concord homeowner, solar was about three things: buying less electricity from PG&E, saving daytime solar production for the evening, and keeping the home powered during an outage.
They wanted whole-home backup, with the flexibility to choose what to run if the grid went down. They also wanted to see how each panel was performing and where the energy was going.
Those priorities guided the project, from the equipment selection to the wiring route through the attic.
Choosing the equipment
The finished system includes:
Sixteen REC 420-watt panels, for a 6.72 kW DC solar array
An EG4 18KPV hybrid inverter
One EG4 Outdoor PowerPro battery with 14.3 kWh of rated storage
Tigo TS4-A-O optimizers with CCA/TAP monitoring
The REC panels fit the available roof space well. I chose the EG4 hybrid inverter because it could manage the solar, battery, home, and grid together, including backup operation during an outage.
The outdoor-rated battery enclosure also let us keep the storage equipment outside without using indoor space.
What whole-home backup means here
The system connects backup power to the whole home, but there are still limits on how much equipment can run at once.
The inverter is rated for up to 12 kW of AC output. Actual backup power also depends on what the battery and solar can supply. Battery capacity determines how much energy is stored; it does not, by itself, tell you how much power the system can deliver at one time.
For the homeowner, the practical question is what to run during an outage.
Refrigeration, lights, and internet equipment put a very different demand on the battery than electric heating or several large appliances running together. Managing those loads helps the stored energy last longer.
During normal operation, the battery can store daytime solar for use in the evening. The settings need to balance that daily use with how much charge the homeowner wants to keep in reserve for an outage.
Seeing what each panel is doing
The homeowner wanted more detail than a single number for total solar production.
Tigo provides individual-panel monitoring, along with optimization and rapid shutdown functionality. If one panel starts producing less than nearby panels under similar conditions, that gives us somewhere to start looking. Shade, debris, a connection problem, or an equipment issue could be responsible. The monitoring helps identify the pattern; it does not automatically identify the cause.
EG4 monitoring shows the rest of the system: solar production, battery charge, household consumption, grid import and export, and inverter status. Together, the two platforms let the homeowner check both individual panels and overall system operation.
The installation details
I used RT-APEX rail-less mounting to keep the array’s profile low and reduce visible mounting hardware. That choice took some extra layout planning, but it suited the roof and the appearance we wanted.
Where practical, I routed the wiring through the attic in EMT conduit. That kept more conduit off the exterior walls while maintaining a supported, serviceable wiring path. EZ Solar rooftop junction boxes provided the transition from the array wiring into the attic.
We also installed critter guard around the array. The space beneath solar panels can attract nesting birds and squirrels, and debris can build up over time. Closing off that space helps reduce those maintenance problems.
These details are easy to overlook when comparing panel wattages and battery sizes, but they affect how the finished installation looks and how it can be maintained.
Questions to ask about your own project
This project highlights a few things worth discussing with an installer:
What can I run during an outage? Ask about both available power and expected runtime with the loads you want to use.
What will I be able to monitor? Ask to see the monitoring platform and understand what it shows before the installation is finished.
Who handles utility approval and final settings? Confirm what operation is permitted while approval is pending and who will configure the system once approval is received.
Who handles a warranty problem? Find out who diagnoses the issue, works with the manufacturer, and handles replacement labor—and what costs the warranty actually covers.
Planning solar or battery storage?
If you’re considering solar, a battery addition, or backup power, send me your project city, a few photos, and what you want the system to do. I’ll help you work through the options and next steps.
Gelfer Electrical Services Licensed California C-10 Electrical Contractor · CSLB #1159194Serving San Francisco and the Bay Area. Selected Mendocino County solar and off-grid projects considered by arrangement.
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