Grid-tied Solar plus Battery: Couple Exemplify Low-Carbon Lifestyle

David & Emily Takahashi - SunPower solar system, Boulder, CO

David & Emily Takahashi – SunPower solar system, Boulder, CO

Emily and David Takahashi are committed to living a low-carbon lifestyle. In 2012 they moved into their 60-year-old, 900-square-foot Boulder, CO home. David explains, “Our aim is to be independent of the electric grid as much as possible.”

Their first step was to have their home retrofitted for energy efficiency, e.g. insulating ceiling and walls and installing triple pane low-E windows. David’s words of wisdom: “The cheapest energy is the kilowatt hour you do not use.” Another significant thing they did was eliminate the gas line to their house. “We’re now all electric.”

Next came getting off the grid or at least getting off grid power. They hired Independent Power Systems to design and install a grid-connected-yet-fully-off-grid-capable power system.

“Our house is directly powered by the solar system. There are SunPower panels on the southeast and northeast sides of our roof.”

Solar energy not immediately consumed by the Takahashi’s home will be stored in a 32kWh Blue Ion battery bank for use at night and during inclement weather – and any time solar energy is not keeping up with the house load. When the batteries are full, the excess energy will flow to the grid earning the Takahashis Renewable Energy Credits and providing their neighbors with clean energy.    

The power system utilizes the Outback Radian GS8048 inverter, two FM100 charge controllers and Tigo optimizers on every solar panel (for maximum production).

This system will produce surplus energy in the summer months and will occasionally have an energy deficit mid-winter, but overall the system will provide close to 100% of the Takahashi’s daily energy needs with solar energy.

Whenever the panels are snow-covered for an extended time, grid power will be used as necessary to power their house loads but will not be used to charge the battery. When the sun re-emerges and the battery recovers, their home will once again operate fully on sunlight.”     

10.4 kW residential SunPower solar system
Carbon neutral home, Boulder, CO

A resiliency beacon in the darkness!

David says he actually looks forward to a power outage when the street’s houses are dark “and there will be ours lit up and fully functioning.”

It’s not so hard to achieve a low-carbon lifestyle.

As part of their low-carbon footprint sustainability lifestyle, the Takahashis also grow some of their own food. Occupying much of their front yard is a high-yielding strawberry patch. “And in the near future, we plan to get an electric vehicle” says Emily.

The Takahashi home was on the fall 2017 Green Home tour. David says, “We’re eager to share our home as an example of how homeowners can live entirely comfortably while being more energy efficient and fossil fuel-free. We want to show how  this can be done in steps. By taking advantage of available energy efficiency programs and rebates, it is affordable.”


Solar panels and strawberry patch.

Solar panels and strawberry patch.

System Specs:

  • [29] SunPower X360 modules; 10.4 kW system
  • [2] Blue Ion /Blue Planet batteries, 32 kWh
  • Outback Radian GS8048 inverter
  • [2] FM100 charge controllers
  • Estimated Annual Production:  7,708 kWh

Independent Power Systems can help you design a solar plus battery-backup system suitable to your needs. Give us a call!

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