Looking at a house that is totally Off Grid. Has solar and diesel generator. Not sure about batteries. I've heard that Powerwalls are not the best for totally Off Grid.
Comments?
Comments?
Off Grid
- Thread starter getakey
- Start date
If its completely off grid and has solar, it likely also has some sort of battery storage already. I have never owned a home that was off grid, but watching the "home shows" where some of them show off grid homes, when those homes have solar, they normally also have some sort of battery storage along with it. completely off grid + solar without battery storage would be a bit confusing, not sure anyone would do that.
Vines
Active Member
Powerwalls can be configured for off grid mode but not many people have done it to this point. They treat the generator source as the grid source, and have some limitations such as lack of strong DC source for off grid DC appliances.
It depends on whether you want to tweak it yourself or set it and forget it. Powerwalls aren't ideal for those who want to get down into the settings of each option menu, there simply isn't much for the user to do or change without Tesla.
If that is the sort of user you are, then an Outback system is probably more up your alley.
It depends on whether you want to tweak it yourself or set it and forget it. Powerwalls aren't ideal for those who want to get down into the settings of each option menu, there simply isn't much for the user to do or change without Tesla.
If that is the sort of user you are, then an Outback system is probably more up your alley.
Thats what I was thinking. A while back we looked at another off grid house that had a fairly large lead acid battery. The wiring looked like a fire waiting to happen
djp
Model 3 Performance
What exactly is the difference between “off grid” mode and “self powered” mode? I haven’t seen any documentation from Tesla on the off-grid option.
The Powerwall can be configured a full offgrid mode and you can charge the powerwall with some generators. You need to contact tesla in order to provide you with the list of generators that allow this. For this cases, you need at least two powerwalls and you cannot connect the system to the grid.
aesculus
Still Trying to Figure This All Out
The problem with pure solar and powerwalls is feast or famine. You cannot guarantee a consistent generation. For example you will probably over produce during the summer and underproduce in the winter. Off grid there is no place to send or get power from.
So IMHO the best you could do was to generate enough solar that met your summer usage with powerwalls and supplement with a generator for winter months. And if you have electric heating that probably won't work.
So IMHO the best you could do was to generate enough solar that met your summer usage with powerwalls and supplement with a generator for winter months. And if you have electric heating that probably won't work.
I think @aesculus summed it up perfectly. By the time you spec out a system that generates and stores enough power to see you through the longest imaginable period of cloud/rain/wildfire haze, etc., you’re over generating 99+% of the time just to be prepared for the edge case. That’s certainly doable, but it makes for a very pricey setup.
Vines
Active Member
There is no reason to overthink this. You have a generator for cloudy days, the Gateway 2 will send a control signal to the generators to start when the batteries are low on cloudy days. Most off grid homes have a pretty efficient power profile so there is no reason why 2 Powerwalls wouldn't be plenty. Yes, you have to ensure a good generator to keep a charge during winter, same as any off grid setup. Ask your off grid friend what their current battery storage looks like in terms of kWh they can utilize, its likely smaller than 26 kWh.
The biggest downside is that there is no way to Tesla approved way to connect to a grid as well as the generator.
Off Grid mode is where a generator is wired in where the main grid connection would be and control circuitry from the GW2 tells the generator when to start. It is a totally different electrical connection and firmware setup that is not similar to any of the 3 modes you can put Powerwalls in as an average user.
The biggest downside is that there is no way to Tesla approved way to connect to a grid as well as the generator.
Off Grid mode is where a generator is wired in where the main grid connection would be and control circuitry from the GW2 tells the generator when to start. It is a totally different electrical connection and firmware setup that is not similar to any of the 3 modes you can put Powerwalls in as an average user.
i really wish we could have a generator as a fail safe for when the batteries get low but still use the grid.. I guess there are to few of us looking for this to make it actually work in a somewhat elegant fashion...
Vines
Active Member
Yup, this question comes up pretty often and there isn't a great solution if you want both grid and generator, and you want the generator to charge your Powerwalls.
You can have generator as a second backup failsafe after the Powerwalls deplete and the grid connection as well but then the Powerwalls cannot charge off the generator.
I outlined a hardware solution a few weeks ago, but no idea if Tesla is working on this.
Went to look at the property yesterday. They replaced panels and inverter a couple years ago, so they are fairly new. However, battery is a grid of lead acid batteries. Not sure if those were replaced at the same time. Seems like lead acid is common in off grid applications.
Vines
Active Member
The company I work for has installed many lead-acid systems, usually paired with a couple sunny islands, or Outback inverters. They are solid and long lasting when well designed. Replacement of the bank is somewhat costly, but this can be somewhat mitigated by proper maintenance and charge control for the style of batteries. Often people chose AGM or another maintenance free battery style at the expense of some lifespan usually. You can get 10 years on a bank of high quality Lead acid cells.
Simple FLA are the cheapest and when properly maintained, and kept above 50% DoD they are very long lasting. This means you need a larger reserve of batteries, not a bad thing if you are limited in winter access.
With the right transfer switch and battery inverter inverter there is no reason why you couldn't have a FLA as a backup to the off-grid Powerwall backup system, just like you would do with a ICE generator in an on grid application, though that would add complexity that's not necessarily desirable.
The path of least resistance is to keep the maintenance up with what is there, as what is there is apparently working. When the next large replacement comes knocking then think about going to Powerwalls if you'd like.
Simple FLA are the cheapest and when properly maintained, and kept above 50% DoD they are very long lasting. This means you need a larger reserve of batteries, not a bad thing if you are limited in winter access.
With the right transfer switch and battery inverter inverter there is no reason why you couldn't have a FLA as a backup to the off-grid Powerwall backup system, just like you would do with a ICE generator in an on grid application, though that would add complexity that's not necessarily desirable.
The path of least resistance is to keep the maintenance up with what is there, as what is there is apparently working. When the next large replacement comes knocking then think about going to Powerwalls if you'd like.
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