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Solar inverters are evolving to support smart home energy storage

Reality is, that most people who want solar power on their home actually want energy storage as well. We want energy storage because if the grid goes down, we want our house to run smoothly – day or not, sunny or cloudy. Additionally, many of us hold onto the dream of disconnecting from The Man.

At SolarPower International 2017 it was clear that the solar+energy storage hardware market – SolarEdgeSonnenBYD, Kehua, Outback, Hauwei, Schneider and others – are almost ready (or in terms of Sonnen/SolarEdge/Schneider – ready today) to serve the home energy demands of the broader population.

First, a small bit of education. The large majority of solar power installations installed today need special wiring/extra hardware in order to keep pumping electricity into the house when the grid goes down – this is due to ‘anti-islanding‘ laws. It’s probable that your solar system will also shut down when the grid goes down. This will change.

Outback and Schneider are the old-time players in the off-grid solar market that I’m most familiar with. The Outback FlexPower is a respected package of hardware (first image on the left below). Personally, my favorite installation was of a Schneider system I developed for a close friend at their off-grid cabin in the western hills of the Rocky Mountains (four images to the right below – including their pool). These systems offer all of the wonders of modern life – including the aforementioned pool.

However, there is a drawback to the design of a standard off-grid system if there is a central power grid available – inefficiency and higher cost. These systems, by default, first send all of the electricity into the batteries to charge – and then draw electricity from the batteries into the inverter to power the house. Having a pure Solar-battery DC charging line is the most efficient path we take. A second drawing back is paying for batteries and extra connection hardware. Though, the constant chatter I hear from readers like you – and watching the headlines here in Electrek – is that battery demand is there and the pricing is starting to come in line.

The below image is of the SolarEdge StorEdge presentation at Solar Power International. The best part about the StorEdge is that you can get it today. In late 2016, I managed an install of one in my neighborhood (I usually do commercial installs – so it was a treat to work with new hardware). When the grid goes down on a StorEdge and there is a battery installed, the system is smart enough to recognize these variables, and continues to pump electricity into the house – allowing the battery to stay fully charged until the sun goes down. As the battery is needed – the SolarEdge hardware will manage the situation.

The StorEdge was initially designed to work with the PowerWall battery kit from Tesla. Since this time, per the SolarEdge representative, SolarEdge has been working hard to make sure their hardware will work well with many battery manufacturers. The large grey box to the right of the above image is an LG 10kWh energy storage unit. That’s a standard ‘dummy’ energy storage kit – batteries and minimal electronics.

This is the same path that a few other inverter manufacturers are now following. Below is an image from Huawei’s SmartFusion on the left, next to Delta’s upcoming hardware on the right. The hardware is being set up in a consistent pattern – an emergency load of items you want to run when the grid goes down, separate from the broader house, being the most important. Notice the Huawei image on the left – fridge, tv and lighting under the emergency load. You, the homeowner, will have to make a choice what hardware you place on that emergency load.

SolarEdge and Delta stated that the default, constant maximum voltage that would run through their hardware when running on pure batteries was 5,000W. This is probably related to standard battery technology – system sizing, currents, costs, etc.

One more item that was continually found in this home energy storage system – home electric car chargers. The Delta image above shows one. Below you see the SolarEdge car charger and their app so you can watch what’s going on. This integration coming from the manufacturers will help your installer know what hardware to offer, and lower the pricing overall. Factors such as whether you might use your car to back up your house are a decision to make as soon as possible.

Professionally, the last three residential customers who I consulted on their projects all had car chargers, or energy storage hook ups included. Interestingly, only one of the three had an electric plug-in car – and none of them have energy storage yet. But that’s going to change – and for many of us its happening right now.


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