In process of getting PV and PowerWalls installed by separate companies. PWs were installed this week but PV won't be on for 1-2 weeks when utility switches out meter to one supporting net metering. PWs are set to Backup mode meanwhile but don't appear to be charging from the grid. Should/Can they be? There also doesn't seem to be away of changing the reserve % charge in Backup; should this be changeable?
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
New install setup
- Thread starter zƬesla
- Start date
chrisbailey13
Member
I am not sure about the charging...I thought if you didn't have solar, you could charge PowerWalls from the grid. If the PowerWalls are set to Backup, there is no adjustment to the reserve %. That adjustment only exist in self powered mode.
Powerwalls not connected to solar would normally be able to charge from the grid... but I have no idea what state the OPs equipment is in. If the Powerwall installer knew that solar was "going to be" installed, they may have not connected / set it up to charge from the grid.
The other thing I would be concerned about is, if this system does not work, how are you going to get anyone to accept responsibility to fix? I would have had the solar setup first, then the Powerwalls would be just "attaching to existing solar" like they normally do... vs the PV installer needing to know how to wire in the powerwalls.
There must be a heck of a good financial reason for splitting it up like that, I am sure.
The other thing I would be concerned about is, if this system does not work, how are you going to get anyone to accept responsibility to fix? I would have had the solar setup first, then the Powerwalls would be just "attaching to existing solar" like they normally do... vs the PV installer needing to know how to wire in the powerwalls.
There must be a heck of a good financial reason for splitting it up like that, I am sure.
Actually, no. Getting PWs was decided after PV agreement, plus we’ve had to do pole mounts. The PV installer could not get signed up as a PowerWall installer because of volume commitments. We’re in a rural area where Tesla itself doesn’t install. There are 3 certified installers listed on the Tesla site for local Zip, and only one that passed some mild due diligence. Timing just worked out that PWs went in a few days before PVs were completed. They coordinated though and hookups/warranties are not (should not be) an issue.
Regardless, It’s a matter of waiting for electrical company to switch meter before enabling self powered mode. Until then, there’s about 14% charge. Unless there’s an outage, probably not an issue. Installer said to contact Tesla support; just figured others here may have an idea.
Regardless, It’s a matter of waiting for electrical company to switch meter before enabling self powered mode. Until then, there’s about 14% charge. Unless there’s an outage, probably not an issue. Installer said to contact Tesla support; just figured others here may have an idea.
I am just guessing, obviously, but my guess is, since the PW installer knows that the systen will be connected to PV, they did not configure / set it up to charge from the grid.
This would be my guess as well. Especially if the PV is set up and connected but PTO hasn't been given (due to the meter change pending).
@zƬesla in "Backup" mode there is no concept of a reserve %, the Powerwall stays at the highest charge it can in perpetuity. If you set it to "self powered" mode then the reserve % is what keeps some in the tank (so to speak) in case of an outage.
CrazyRabbit
Active Member
if you don't get a tax credit for the powerwalls then they should be configured to charge from the grid...
What percentage to set it at is a pretty personal decision, there is no "correct" answer for this. For my own personal use case, that percentage depends on a few different things, so I change it manually fairly often in fact.
In general, the "reserve percentage" is "the percentage of total powerwall energy I want to leave in my powerwalls, so that they have power in case of a power outage".
A little more specifically, its the amount of power you think you will need in the powerwalls to last you until the sun comes back up again and starts charging your powerwalls again, in case of a power outage. You can put as much or as little thought into it as you want. In my specific case, when I got my powerwalls installed in January, I had the reserve percentage set higher than I do right now (because my PV system makes less power in january than it does now, as do most peoples).
Right now, on a sunny day, my PV system can fill my (2) powerwalls from 25% to 100% by about 12noon to 12:30pm, even with the PV covering the house draw as well. I have my reserve set to 25 percent, because, I just need enough power in the batteries overnight to ensure that, if the power went out while I was sleep (minimal draw anyway during that time for me), the powerwalls would power the house till the sun came up.
That number is going to be different for different people with different electricity usage profiles, and also whether they are on a time of use plan (and thus trying to cover peak usage during a regular day) or not. Since I am not on time of use, but a regular old school tiered rate plan where the more you use the more they charge you, WHEN I use my power doesnt matter. Its no cheaper for me to use power in the middle of the night than it is during the day on my plan. I get charged more for how much total I consume, so I am incentivised to reduce my usage as much as possible, in total.
I also change my reserve percentage manually, if (for example) I know there is going to be rain / overcast the next day, so I am going to generate less PV power. I bump it up manually to a higher reserve number, because if its overcast / raining, I generate less PV energy, so "if" the power went out, the powerwalls would have to cover me longer. My goal is to NEVER AGAIN EVER deal with having "no power" while I am living in this house again (ever). I dont mind micromanaging the reserve to ensure I am doing what I can to minimize that chance.
I have 2 powerwalls and wish I had bought 3, because for most of the year I would have no issues generating enough PV to "fill" 3, and it would enable me to charge my car a bit more easily for my normal commute.
Anyway, I dont use the cost savings or advanced modes, so not sure how people set their reserves for those, but the same general thought process applies, which is "how much do I need to ensure is in the battery so that it can power my "stuff" if the power goes out, till the next sunny day".
==========================================================
TL ; DR ?
Powerwall reserve settings are something each person needs to decide on for themselves, based on their expectations and system performance. There isnt a correct way to set it, only a correct way for "you".
