[Question] Self-powered optimal settings?

[inShaneity]

Hello,

Just recently got my 5.6kW panels and 2PW installed with AC hooked to it. I have a probably a dumb question...

If it takes about 2 days to charge the PW and before the sun rises I use up about 80 to 85% of the battery, does that mean I have to keep the reserve for power outage setting at around 35-40% to make sure I'm back at 100% before the sun sets

Right now it's at 0% reserve for outage, but I doubt it will charge to 100% from the current 15%. I believe I can get 70% charge on a normal day. Essentially, the battery will empty out in the middle of the night as the charge won't keep up during the day.

I'm still playing around with the settings and understanding fully how it works. Noob here.

 

[NuShrike]

Hello,

Just recently got my 5.6kW panels and 2PW installed with AC hooked to it. I have a probably a dumb question...

If it takes about 2 days to charge the PW and before the sun rises I use up about 80 to 85% of the battery, does that mean I have to keep the reserve for power outage setting at around 35-40% to make sure I'm back at 100% before the sun sets

Right now it's at 0% reserve for outage, but I doubt it will charge to 100% from the current 15%. I believe I can get 70% charge on a normal day. Essentially, the battery will empty out in the middle of the night as the charge won't keep up during the day.

I'm still playing around with the settings and understanding fully how it works. Noob here.

Do you get any credits for feeding solar back into the grid? You should prioritize that to best zero out your bill.

Also, you lose 15% of your energy on its round trip in/out of the battery it it works against your solar-credits/ROI to charge too much off solar.

The battery self-protects around 10% reserve, so if you go below that it will no longer power your loads.

 

[inShaneity]

Do you get any credits for feeding solar back into the grid? You should prioritize that to best zero out your bill.

Yes, but shouldn't I do that when the batteries are at 100% to maximize not using energy from the grid during the night? Obviously, this will change during the winter and I'm also on my like 4th day using the system.

Also, you lose 15% of your energy on its round trip in/out of the battery it it works against your solar-credits/ROI to charge too much off solar.

You lost me here...

QUOTE="NuShrike, post: 3858822, member: 68028"]The battery self-protects around 10% reserve, so if you go below that it will no longer power your loads.[/QUOTE]

So even though the battery displays 0% and the self-power outage reserve is currently set to 0%, the battery still holds 10% in case of outages in secret? That's kinda nice. My current mindset/setup is to utilize the batteries at night when there is no sun. The fact that the battery can't reach full charge before the sun sets has me concerned that I needed more panels to begin with (the second battery was added last minute so it wasn't calculated from the beginning). I also don't want to keep adjusting the settings on the app as the backup-only mode forces all solar to go the battery, but then it won't use it at night.

 

[jakestgermain]

Do you get any credits for feeding solar back into the grid? You should prioritize that to best zero out your bill.

Also, you lose 15% of your energy on its round trip in/out of the battery it it works against your solar-credits/ROI to charge too much off solar.

The battery self-protects around 10% reserve, so if you go below that it will no longer power your loads.

If you keep your battery at 100% backup will it still lose the 10-15% roundtrip or will the solar energy bypass the battery and go right to the grid?

 

[inShaneity]

If you keep your battery at 100% backup will it still lose the 10-15% roundtrip or will the solar energy bypass the battery and go right to the grid?

From what I saw, still not sure what that roundtrip is, if the battery on the Tesla app reads 100%, solar will send power to the house and send the rest right back to the grid.

 

[NuShrike]

From what I saw, still not sure what that roundtrip is, if the battery on the Tesla app reads 100%, solar will send power to the house and send the rest right back to the grid.

I guess nobody else is going to take this.

If you put 1000 W into your battery, you will only get 850 W of it back, after counting all the losses, so avoid using the battery as a buffer when you don't need to. Example, charging EV from PW instead of just straight from the grid.

So even though the battery displays 0% and the self-power outage reserve is currently set to 0%, the battery still holds 10% in case of outages in secret? That's kinda nice.

Once your battery drops to 10% charge left, it will no longer power your house nor any other loads until it's recharged to a higher level.

Self-consumption mode doesn't require your battery to charge to 100% before use.

 

[inShaneity]

I guess nobody else is going to take this.

If you put 1000 W into your battery, you will only get 850 W of it back, after counting all the losses, so avoid using the battery as a buffer when you don't need to. Example, charging EV from PW instead of just straight from the grid.

I guess I might be confused on the entire system I just bought into or Tesla didn't really do a good job on explaining the whole thing. Or I'm just confusing myself even more and everyone else on this thread . I don't have an EV so I'm just using the solar and batteries for the house/AC usage, and if a hurricane decides to come on by.

Once your battery drops to 10% charge left, it will no longer power your house nor any other loads until it's recharged to a higher level.

Self-consumption mode doesn't require your battery to charge to 100% before use.

I get that it doesn't need to be at 100 but the reasoning for it is because my house uses about 80-90% of battery on average during the night. Instead of net meetering, which I do have, I'm more focused on using 0 energy from the grid.

 

[jakestgermain]

I guess I might be confused on the entire system I just bought into or Tesla didn't really do a good job on explaining the whole thing. Or I'm just confusing myself even more and everyone else on this thread . I don't have an EV so I'm just using the solar and batteries for the house/AC usage, and if a hurricane decides to come on by.



I get that it doesn't need to be at 100 but the reasoning for it is because my house uses about 80-90% of battery on average during the night. Instead of net meetering, which I do have, I'm more focused on using 0 energy from the grid.

From my understanding(which I may be wrong). If you have 1-1 NET metering then you are better off using your batteries more in the backup mode. You lose much more power cycling everything from the battery than you do sending it directly to the grid and having the battery for backup purposes if you are not on a TOU plan. Someone please correct me if I am wrong.

 

[inShaneity]

From my understanding(which I may be wrong). If you have 1-1 NET metering then you are better off using your batteries more in the backup mode. You lose much more power cycling everything from the battery than you do sending it directly to the grid and having the battery for backup purposes if you are not on a TOU plan. Someone please correct me if I am wrong.

That makes perfect sense! Yes, I should have 1:1 NET metering. Would it also make sense to use the batteries when we get home from work, since that's when the most energy is used? That could possibly be about 30% of the battery. Faster to charge 30% during the day than the 85% I'm currently doing with my misunderstanding of the whole thing .

That way I'll get net during most of the day and save on the most used times. OR will it still be a dumb idea and just keep them as backup from here on out?

 

[jakestgermain]

That makes perfect sense! Yes, I should have 1:1 NET metering. Would it also make sense to use the batteries when we get home from work, since that's when the most energy is used? That could possibly be about 30% of the battery. Faster to charge 30% during the day than the 85% I'm currently doing with my misunderstanding of the whole thing .

That way I'll get net during most of the day and save on the most used times. OR will it still be a dumb idea and just keep them as backup from here on out?

Mine are getting installed in 2 weeks. I am planning on keeping mine completely on backup. We have a 1-1 NET metering here in Rhode Island and I wasn't going to get the powerwalls at first. National Grid ended up coming out with a program that will pay you 1000 per powerwall to allow them to discharge it up to 75 times a year and use that energy during peek events. Plus they are allowing a 7 yr interest free loan through the power company. The batteries basically end up being free at the end if you apply your national grid payments towards them.

 

[miimura]

If you have 1:1 net metering and you have the same price of electricity all day long, then there is no economic value in cycling the batteries. You might as well leave it in Backup mode. However, if you personally put some value on self-consuming your own solar and interacting less with the grid, then just leave it in Self-Powered mode and set a reasonable Reserve so that you will have some energy during an outage. Just let it do its thing and don't worry about it.

I personally pay attention to what my Powerwalls are doing because I have drastically different energy prices at different times of the day and it matters financially whether the Powerwalls are doing the "right" thing, whatever that may mean in a given situation.

 

[inShaneity]

So then the whole point is to keep the 'to grid' higher than the 'from grid' each day since I have 1:1 and the same price all day long.

Cycling the batteries will sometimes not be able to cancel out the 'from grid' portion depending how much charge gets done and how much solar is provided.

Currently I have it set to self powered with a reserve of 75% for back up. My thinking is to use the 25% for when we get back from work as that's where the most energy is used (ac back on, computers, tv, cooking, etc.).