Energy storage and inverters to get you through power outages

Share

Pacific Gas & Electric (PG&E) has begun Public Safety Power Shutdowns, with the first phase affecting just over 500,000 households, the second phase affecting 234,000, and the third phase affecting 4,000. Between 110,000 and 130,000 households have had their power turned back on. The below map, found on this address search website provided by PG&E, shows the regions affected. The company’s Twitter account shows available Community Resource Centers that will remain open during daylight hours with restrooms, bottled water, electronic-device charging, and a/c seating for up to 100.

This article will outline some potential solutions to keep electricity on while Public Safety Power Shutdowns are ongoing.

First, a warning – only a small, single digit percentage of the nation’s over 2 million solar power plants are designed to stay on when the broader power grid shuts down. This feature – called “anti-islanding” – was put in place to protect line workers from electrocution due to solar power systems feeding the grid during power outage events.

AC coupled energy storage

For those of you with a currently installed solar power system of the standard nature, it might be best to consider an AC-coupled energy storage solution. Solutions like this can be found by sonnen, Tesla, Sunrun and others. These solutions, when sized and installed appropriately, can run your home when the grid shuts down.

The sonnenbatterie by Sonnen – probably the most advanced energy storage management solution we have available to residential customers – offers 3 to 8 kW of instant power, and 5 to 15 kWh of energy storage in various products. The hardware has intelligence to predict when power outages might be coming, and manages itself to maximize available electricity. As well, you can program the system to shut down all plugs that aren’t considered mission critical.

The Tesla Powerwall is also in this class of products with its single offering that peaks at 5 kW power output, and 13.5 kWh of energy storage. Tesla recommends two units to meet daily consumption needs. This is because an average American home uses 30 kWh/day – so any of these units will have to be used judiciously. If a homeowner does in fact have solar power (and it isn’t needed for these units to run), then potentially, they can power themselves perpetually.

SimpliPhi offers their battery solutions coupled with inverters from off-grid manufacturers – but these would have to be installed at the time of original install. However, they can be added in relatively simply as they come in a clean package.

Inverter solutions

A second solutions involves a product from global inverter manufacturers SMA and (maybe – if it made it into production) SolarEdge, but these are more complex retrofits that would involve changing out hardware if you’ve not already installed these devices.

SMA’s solution is called the “Secure Power Supply” and it is integrated into a large number of its residential solar solutions. SMA has released a video on it. The unit, essentially, lets you use up to 2 kW of electricity when the grid goes down, as long as the sun is up. It really is just a place for you to plug directly into the inverter. A simple solution.

SolarEdge’s HD Wave was pitched with a “Self-Sustaining Power Outlet“, which is very similar to the SMA unit above. The hardware allows for a 1.5 kW max power output and is available in the company’s HD Wave 3,000 and 3,800 watt units. edit: A reader has notifed pv magazine USA that this feature might not have made it into production hardware.

Battery add on to current inverter installed solutions

Groups like SimpliPhi, LG, Panasonic and others offer energy storage solutions that must be coupled with inverter solutions. Currently installed solar inverters should be able to integrate these solutions, however, it’ll be necessary to do some extra wiring to integrate the hardware. It is also possible that the inverter will have to be changed out to handle this hardware. SolarEdge’s StorEdge solution offers an inverter that can be installed without energy storage, but can later – cheaply and easily – have energy storage added in.

Lastly, one future solution is coming from Enphase – the IQ8. This system has the integrated intelligence to listen to electricity demand coming from the home, and to deliver as much power as it can via the available sunlight at that moment. This system will not power your home after sundown. Unfortunately, the product isn’t available yet.

 

A very new, and extremely short as of now, pair of lists has been started by the California Energy Commission (CEC) as of August 27, 2019 for purpose of tracking battery and energy storage solutions approved by a state regulatory review body. Currently, Sungrow has three energy storage solutions, and e-On batteries has a single battery on the list. The CEC solar module list has thousands of modules and has become a nationwide standard.

Preparation & microgrids

There are many areas of the state that have been planning for these outages. For instance, the City of Calistoga, California has solicited Clean Coalition to conduct a feasibility analysis for developing a community microgrid as one potential tool to manage the Public Safety Power Shutoffs (PSPS) that will come during the California fire season. The below image is the fire threat map of the city put out by the electricity utility, essentially noting that the whole of the city – and specifically the 60 kV power lines coming into the city – surrounded by fire risk.

Per the above linked to map provided by PG&E, the city is currently affected by the power shut offs.

If any readers have questions, please don’t hesitate to sent them to usa-editors@pv-magazine.com. We will do our best to get your request to qualified contractors, or to direct you to manufacturer’s websites. We do suggest also reaching out to local solar and electrical contractors that can be found on various websites. This great, searchable member list from the California Solar and Storage Association happens to represent many manufacturers, installers and others focused very specifically on this topic in California – so it is probably a great resource to tap into.