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Getting to safe, reliable, zero maintenance residential storage

image credit: © Leowolfert | Dreamstime.com

This item is part of the Special Issue - 07/2020 - Energy Storage, click here for more

Like it or not, electrification is coming — for some fast, and others slow, but it is coming. With that comes electric vehicles and rooftop(backyard) solar. As with the issues air conditioning caused in the 1960s and 70s, electrification will cause issues from now until who knows when.

Some argue that the grid is dead and that microgrids will handle all the issues — until confronted with the energy density of vibrant major cities, like Toronto or New York. There just is not enough available energy in the wind and sun to produce what is needed locally. Likewise, if we proceed with an all-electric future, then our grid may not be ready to support the movement of energy between both location and time. Location issues mean a more robust grid; time means a way to save it for the future. A tool that needs to be in the toolbox is small customer storage. Residential, small commercial and even very small industrial sites may need storage. Even most microgrids will do better with storage. Regardless of overgeneration or too much demand, energy has to move, and it also has to be available when people want it under today’s regulatory rules. There is no busy signal on the electric grid.

When it comes to residential storage, it is important to determine if the products currently available in the market solve the residential storage issue. In short, the answer is no. NFPA-855 raises multiple safety related issues and, to go a step further, these products, like the batteries in today’s cell phones, eventually stop working as the batteries degrade. It also is not quite a “set it and forget it” piece of equipment. Lead-acid batteries and other technology have been suggested, tried and largely discarded over time for various reasons, including cost. Nothing on the market today is an ideal product to install for residential storage. So, what do we really need?

Proposed requirements for residential storage

  1. The storage system needs to be safe. Safe from fires, shock, electrocution, toxic materials, hacking and other hazards in the typical residential environment. Ideally, the systems are even safe from customer accidents, like accidently driving the car into it, or having a rack of heavy tools or a ladder fall on it. It needs to be child safe, even if the child is using it as a jungle gym, or a catching mitt. And it needs to be easy for UL to certify and for insurance companies to welcome into the home.
  2. The system needs to require zero maintenance, because, in reality, most appliances in the home, like the breaker panel, seldom gets any maintenance. Furnaces? Maybe the air filter gets changed on occasion, but even that is too much maintenance for many. Smoke detectors were updated to use the home wiring, instead of batteries because many people would not change the battery. Storage systems need to be maintenance free. There should be no, none, zero components that are user serviceable.
  3. Residential storage should have no communications with the outside world. It should be self-contained and autonomous. From the resident’s view, the storage system should never be a vector to hack into the energy system and most residents won’t want to worry about a cell phone number or an IP address. While communications may be desirable from many views, from a pure risk point of view, no communications might be the best option.
  4. The system needs to be easy to install, light enough in its shipping configuration to easily move with two people and a truck. It should not exceed typical wall loading and floor loading limits. It should meet all the building code and National Electrical Code requirements. It should not require a separate breaker panel or major re-wiring of the premises. If it cannot be delivered, setup and running in two hours or less, there is a problem.
  5. Storage systems should be able to provide power in an outage. That means that they need to be able to supply normal activities, through normal wiring in the premises. What type of islanding scheme used is not important, but the premise should be able to island and continue to operate for a pre-defined period of time.
  6. A home storage system should be able to charge from both alternating current (AC) and direct current (DC) and deliver both AC and DC to loads in the premise.
  7. The systems should be able to last as long as a furnace or air conditioning system in a home, typically 20 years, without replacing any major components.
  8. The system should be able to installed in any basement, garage, or car port — even outside, next to the doghouse, in any weather, without missing a beat. If the basement floods, or rain falls for several days, the storage system should be able to continue to operate, as soon as water levels recede to a reasonable level.
  9. There should be no reason for a fire suppression system or other ancillary system to support the storage system, nor should the storage system require one. Not even a fan should be required as part of the storage system.
  10. It should be noiseless. The only indication that it is working might be an LED under the “ON” switch on the system.
  11. It should be 100% recyclable. Nothing in the system should have to be handled as hazardous waste, every component or material used should be easily recycled, and no smelting should be required to separate materials.
  12. Systems should be modular and in reasonable sizes. That way for a weekend cottage, the smallest system will fit, and more energy can be installed with a simple module that shares the electronics of the first (core) module. For larger dwellings (and small C&I buildings), two or three core modules could be connected to provide the capacity needed, and storage additions added to support the energy needs over the expected product life. For instance, if the resident changes from a gas furnace to a heat pump, they can quickly addthe energy needed to keep the heat pump running during a winter storm outage.
  13. The storage system should have the option to add a controller that can communicate, to an aggregator, landlord, or utility, that allows the resident to say “yes, I will join your program, you can install your controller on my storage system and enroll me.” To this end the data interface and actions should be tightly defined and very well documented, so that when a controller is installed it will just work. The third party that installed the controller now becomes responsible for any risks that opening the system up for communications created.
  14. Finally, it should be marketed like any other appliance, with financing programs available for people who need the support to put one in. It should not be something that is only available to people with lots of cash. Whether it is a utility program or a community program that offers them, everyone who wants one should be able to get one.

If we are successful in creating such a system, then a whole new set of non-wires alternatives will be available. Residential solar will be much less of an issue, and more customers will be able to install it without impacting the grid, garage more EVs on a circuit, and charge with fewer restrictions. Utilities and aggregators can work with customers to drive bills down and keep the load on the circuit reasonably steady each day; less generation will have to cycle. There is much more this kind of a tool can offer. No one has to adopt it, but it would be very good to have it in the toolbox.

Discussions

Bob Meinetz's picture
Bob Meinetz on Jul 26, 2020

"Storage systems need to be maintenance free."

Doug, no system is maintenance-free, and maintenance increases logarithmically with the number of interconnected components.

How could it ever be more economical to equip everyone's home with storage that needs to be replaced every 10-12 years, and a solar array requiring replacement every 30 years (and constant cleaning), all while maintaining a grid connection for exigencies - than to simply strengthen the grid? Above, you provide 14 excellent reasons why such a scenario will never be successful.

Doug Houseman's picture
Doug Houseman on Jul 27, 2020

Bob - thank you for the comment. The goal should be maintenance free. Storage does not have to be replaced every 3-8 years, if you don't focus on Lithium or lead. There are other choices out there that can last several decades. 

The 14 "reasons" should be goals for anyone contemplating residential storage. 

I agree the grid will have to get stronger, and I am actively working to make that happen. Distributed Generation and electric vehicles are the two biggest reasons to make the grid stronger. 

Matt Chester's picture
Matt Chester on Jul 27, 2020

Thanks for sharing, Doug-- there seem to be a lot of great reasons for homeowners to want this. Especially in these times when more people than ever are working from home (and many will likely take that permanently) then having the storage be able to prevent interruptions can become even more important and valuable to them. 

If you look in your crystal ball, what sort of timeline would it take before getting systems installed widely that meet these 14 criteria? 

Doug Houseman's picture
Doug Houseman on Jul 27, 2020

If we focus on it, we could build enough units in 3 to 5 years that meet these goals to have residential storage with the costs of at scale manufacturing. 

The issue is, most people and companies are focused on the wrong technologies, and the wrong sizes of storage for this to work. it will take an outlyer to get us to the goals. (No Tesla is not an answer - wrong technology focus).

Doug Houseman's picture

Thank Doug for the Post!

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