Off-grid and Hybrid Systems

Our method is to combine battery, solar and DC loads to simplify and reduce the costs of smaller scale solar projects.

ATX LED DC lighting has been installed in 85+ houses with 48 volt lighting, and so far 2 use the proposed method.

In conventional grid-tied solar, energy suppliers worry about inverters feeding back to the grid. If you do have inverters and don’t feed back to the grid, regulations are simpler—for example in Austin a second meter, billing account, permitting, and costs for backfeed protection and extra 200 A main cutoffs burden the project, cutting the value of energy you produce in half.

Therefore, a system that lights, cools, exhausts and charges a dwelling with DC current, without any inverter, has no impact on utility grid tie. Indeed, the method proposed is less variable than a grid-tied solar system.

The DC is generated by solar and stored in a battery sized for the project. The battery is a recycled EV battery pack (3.5 kWh) kept at full charge by an algorithm that consumes grid power from time to time.

The house has an AC/DC converter that runs the home when solar + battery state is unable to. Excess solar capacity over the battery charge rate, when the battery is full, is shifted into the house, reducing grid demand. An algorithm directs power to minimize grid use and ramps demand down as daylight wanes, then ramps back up as the battery depletes after dark.

No power is fed back to the grid—eliminating 25% conversion loss and the need for two utility meters and cutoffs. Using a recycled Leaf battery at 380 V reduces cells and size: five battery sets are electrically safer. ROI is driven by reduced utility rates (23 c/kWh peak vs 9.7 c off-peak) even with no net meter.