A ‘double zero energy’ home with energy storage and solar PV systems has been launched in the US, as a result of the partnership between solar manufacturer and developer SunPower and homebuilder KB Home.
In June, the two companies extended the terms of an existing partnership whereby SunPower panels are fitted to some of KB Home’s range of production-line houses to encompass a pilot of energy storage. Batteries fitted to new homes at present are used only for backup power, to ensure an uninterruptible supply even in outages.
However there is an expectation that the scope of this pilot, which at the moment has only been rolled out in California, could be extended in future to include night-time use of PV-generated electricity as well as other regional markets. At present, for the most part, residential rooftop PV systems in the US are compensated for their generation by net metering schemes, which exist in 43 states.
According to sources including Chris Edgette of the California Energy Storage Alliance (CESA), unlike regional markets elsewhere such as Germany, this means that – at least from an economic perspective - self-consumption of PV generated electricity is of little interest in California and most of the rest of the US at present.
“Because of net metering, California allows net metering where the PV can basically generate at whatever time of day it generates and it can put that power onto the grid and get paid at the retail rate,” Edgette said.
“There’s no benefit to storage in that instance because all you’d be doing is losing some power when you charge it one time and discharge it another time.”
However Edgette said it was possible steps toward enabling storage to go further than just providing backup capabilities could be taken in California before long, for two key reasons.
“One is that people realise that NEM won’t last forever, so they’re preparing for the time when we will have to do self-consumption like Germany, or some form of that.
“The other thing that’s going on is because we have net metering, there is an interest at the independent system operator level - the folks that operate the vast majority of the California power grid - in having resources that can act as storage and it’s interesting because there are multiple approaches. One is to have big utility-scale units that are sitting out like traditional generators that provide regulation and different services to the grid. The other is to have many low-cost systems that are installed out at customer sites, and then all of those systems if you install the right controls can be aggregated together. This is actually done with demand response where one provider can control a thousand customers’ systems. Except in the case of storage, they can be highly grid-interactive.”
In addition to the partnership with SunPower, the design of the new house also incorporates features provided by link-ups with carmaker Ford, which provides a smart energy management system that interacts with its C-Max Energi plug-in hybrid car, and home appliances maker Whirpool. The system provided by Ford comes from Ford’s MyEnergi Lifestyle initiative, and allows management of power use to the extent that homeowners can reduce overall usage as well as shifting electricity use to mitigate the financial impact of time-of-use charges.
Double ZeroHouse 3.0, as KB Home has called it, builds on the company’s concept of a net zero energy dwelling by adding ‘net zero’ water consumption to its existing energy efficiency measures. The house’s water systems recycle water used for washing dishes and other applications, for toilet flushes and other non-potable uses. The maker claims that up to 70% of the fresh water used can be conserved in this way.
KB Home is one of North America’s production homebuilding companies – serving mostly first-time buyers, KB Home offers a range of housing types that can be customised, built in community developments. The Double ZeroHouse 3.0 has been debuted at a community in El Dorado Hills, California.
SunPower chief executive officer Tom Werner, recently interviewed for PV Tech’s forthcoming print magazine PV Tech Power, spoke about the potential of the piloted link-up with KB Home. Werner also spoke further about his company’s ambitions and activities in storage.
“The value proposition in the near term is battery backup and KB Homes is quite a progressive company. Some of the things we’ve talked about are in the early stages of developing with KB Homes. So expect more from that relationship. It may not mean that much [to an international audience] but there are production home builders in the US, of which the top 10 probably produce 80% of the homes in America, and KB Homes is one of those. So it’s a meaningful company that we’re partnered with in California.”
“Secondly, we have a pilot in Australia. Australia has a fascinating energy market, it’s actually deregulated and it’s more of a competitive market than almost any other electricity market in the world. So the pilots we’re doing are quite advanced in the value that storage can add. Thirdly, we’ve announced a partnership with Audi-Volkswagen, where they will offer SunPower Solar and Storage to their customers. Then you start integrating how you charge your electric car with storage, and how you might use the EVs battery in the other direction. That’s not something that’ll happen in the short term but in the longer term it’s very interesting. So, an important area is that we’ll start introducing storage into the German market. We’ve got four fronts that we’re working on, so we’re quite active.”
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