Kiloboost: PV Surge Capacity For Off Grid Power And Battery Protection

The conventional method for configuring a grid-tied photo voltaic (PV) system for whole-house power during a power outage is to add an energy storage system (ESS) with large bulk batteries. The problem is that when air conditioners and other large appliances start up, they momentarily (1ľ3 seconds) produce surge loads that can be 2-4 times the average load. Surge loads are normally absorbed by the grid, but during an outage they must be handled by the PV/ESS system. In many cases, the batteries must be oversized by 3-4 times to accommodate this surge power ľ adding up to $20,000 (or more) to the cost of a residential PV system. Additionally, Lithium-ion batteries, the most common type used for bulk storage, are optimized for stable loads. Repeated surge loads can damage the batteries and dramatically shorten their lifespan. Lithium-ion batteries also present a host of environmental and humanitarian issues, from extraction to disposal. Some models estimate that this natural resource will be depleted within 20 years. Equipping facilities with kilowatt-hours of batteries that sit unused for most of the year is imprudent at best. A more effective approach for backup power is to size the bulk batteries for steady loads and employ an alternative technology for surge power. Our technology will provide cost-effective surge power capability to a system, allowing a homeowner to size a backup system for the average loads instead of the peak loads. Our technology can reduce the cost of a whole-house PV backup system by 75% or more. Our technology will also shield the installed Lithium-ion batteries from the surge loads, protecting them from potential damage. In Phase I we will partner with a national lab to perform battery/inverter integration studies to optimize the Kiloboost modules. Specifically, we will determine what output parameters (voltage, current, ramp rates, etc.) best protect the bulk batteries from degradation and will develop specifications and a testing approach to ensure the Kiloboost modules function with a wide range of inverter and battery technologies. Residential whole-house PV backup power is currently unaffordable for most Americans, and is therefore in desperate need of market ready solutions. The proposed technology can have a significant affect on the backup market, and also help to spur PV and ESS sales, as more residents will be able to afford these solutions.