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David & Emily Takahashi – 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 with the dream of going “off the grid” and cutting the cord. Their first step toward a net-zero home was to have their home retrofitted for energy efficiency through insulating their ceilings and walls and installing triple-pane low-E windows, adhering to David’s words of wisdom: “The cheapest energy is the kilowatt-hour you do not use.”

Next, they transformed their house to be completely electric by eliminating their gas line in order to completely utilize a grid-connected solar system that is capable of ‘islanding’ from the grid (or going off-grid).
David explains, “Our aim is to be independent of the electric grid as much as possible.”
Solar energy not immediately consumed by the Takahashi’s home will be stored in a 32kWh Blue Ion battery bank for use at night, 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 Takahashi’s Renewable Energy Credits (RECs) and providing their neighbors with clean energy.

Independent Power is a certified dealer of Blue Planet Energy‘s Blue Ion batteries, which are super robust and highly efficient lithium-ion ferrous phosphate batteries that are capable of 100% depth of discharge, which means they are able to cycle completely without degrading the battery over time. With a cycle life of 8000, 25-year life expectancy, and 15-year warranty, Blue Ion is one of the highest quality batteries in the business, especially for off-grid applications.


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

The Takahashi home was on the fall 2017 Green Home tour. As part of their low-carbon footprint sustainability lifestyle, the Takahashi’s 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. 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.”
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.”
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  can help you design a solar plus battery-backup system suitable to your needs. Give us a call!