the problem/complexity with _ANY_ personal power generation/source in a residential context is the following…
during a power/grid outage you MUST disconnect your home from the grid - so that no power you are generating flows "backwards" on the grid for several reasons:
- safety - power companies don't want you electrocuting their workers while they are fixing the grid
- brownouts - there is no flow control on your meter - if you start providing power to your home-grid - your neighbor's homes will also see "power" and start trying ot use it - it's unlikely you have enough power to provide for your entire neighborhood - so your wimpy power sources will trip into "brownout" (like what happens when you overload a generator in an RV) - and power will come and go
- not to mention your neighbors are now consuming your batteries's capacity and you'll be sucked dry pretty quickly…
so it does not matter the power source: gas generator, EV, Solar, home batteries, Wind etc…if the grid is down and you have your own power source you have to disconnect from the main grid
this is one of many reasons why Solar panels drop offline during a grid outage…there are others - but you get the point.
I have Solar+Batteries - and they work great - and when you have such a system installed the "key component" is the auto-disconnect switch that happens in 0.25-2 seconds from losing the grid - now that the entire home is "isolated" from the grid (and you won't be killing random electrical workers) you can provide power from your own local sources…
I writing this right now on my solar+battery power system in Santa Cruz, CA where I'm in a grid outage as we speak…lost power at 8:30 am this morning, auto-cut off switch tripped - and I've been running my home on a combination of Solar+batteries all day…
I've been doing EV's since 2011. Solar since 2007, and home batteries since 2019…
99.99999% of North American residential homes are not setup to be isolated from the grid during an outage - and depending on the home and it's electrical panel it ranges from trival to really expensive to get the home "ready" to have this sort of back up system…in this context an EV with V2H capabilities is no different than solar panels or a gas-generator - before it can provide power to your home - the home has to be isolated from the larger neighborhood grid…there are 3 ways to do this:
- throw the main breaker on your power input from the power company
- install a "manual" throw/cut-off switch
- install an automated switch
#1 requires no changes to your home electrical panel - but has obvious draw backs
#2 is slightly better, but still requires you to throw the switch and then "start" the local power source (generator, EV, batteries, solar, wind, hydro, kids on a treadmill)
#3 is best, but you then also want this system integrated with your various power-sources to automatically start/stop them based on grid status - this sort of integration is straight-forward and technically feasible - but at the moment there are few if any "standards" to interoperate with - so they are all be-spoke/custom
anyone who has a home generator with an auto-cutover switch already has such a system in their home…
anyone who has Tesla Powerwalls has such a system (or other residential batteries, enphase comes to mind)
Ford Lightening Pro EVSE can power your home - their install included the grid-isolation cut off
etc…
the final complexity is also in most homes there are circuits you'd like to isolate from the backup powersource so they don't drain your resources during an outage - so there is certain amount of redesign for individual breakers that you want to backup and those that you don't want powered during an outage…
the most straightforward approach to this is two separate circuit breaker panels:
- one panel contains all the normal home circuits you want to have power during an outage
- 2nd panel contains all the home circuits you don't want to have power during an outage
- install the cutoff switch between the two panels and the electrical meter
in my personal case I have: Main-Residential-Grid ---> Electrical Meter ---> Subpanel with EV chargers +Main-Home-Breaker ---> Cutoff Switch ---> Home-Power-Management-Controller ----> Batteries ---> Solar ---> All-other-home circuits
during a grid outage the "cut-off switch" isolates my home from the residential-main-grid - and all the stuff 'behind' the cut off swtich gets power from batteries+solar - while the EV chargers since they are "in front of" the cut off switch do not get any power so my eV's charging overnight do not drain my home's batteries before I wake up…
I've given the whole V2H thing a LOT of thought - it could work and work great and would be wonderful - but the simple fact is that there are no-home's that come "ready made" to have a local isolated power source (of any kind) and a simple automated-relay-power-management system to trigger it all during an outage…
this in my mind is the _MAIN_ impediment to V2H systems - the cost to rework everyone's home to have this system "inserted" into their home - and the variable nature since no two homes in North America match a standard design - the cost can range from trival to easy - to extensive/expensive/prohibitive.
Example: I live in an HOA complex with 97 homes built in the mid-1980's - the main electrical panel for each of these 97 homes are similar/identical to each other - with the Meter/Main panel outside the home in a small equipment closet along with the gas meter…all of these homes passed building codes for the time period they were built. But would not pass today - because the gas meter is too close to the electrical panel. Due to local county ordences if you _TOUCH_ the existing electrical panel for any reason (repair, remodel, upgrade, solar) you must bring it up to current building codes - and the requires redoing the home's entire electrical system to have a new panel installed at least 6 feet away from the gas meter - and minimum cost for this sort of change depending on the home, it's floor plan, available outside wall space, etc…starts at about $12,000 _BEFORE_ you've done anything at all…
the "problem" with V2H systems is the redesign/upgrade/reworking of a home's residential power system to integrate the grid-isolation-switch - and the lack of any sort of common design in millions of homes/appartments/condo's - so each home that gets this done is "bespoke" and costs are highly variable.
once you have the residential "home" issue handled - next you have to integration - I'd need my EV to work with my Solar - and for a small fraction of owners like myself I'd want the system to integrate with my existing batteries - and so now we need all the different vendors to agree on how these separate power sources interoperate with each other…
this is all feasible - but it's not just a matter of a bi-directional EVSE - there are a few other things that need to be in place before the EVSE can let power flow from the vehicle to your home…
my $0.02 YMMV.
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