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What do you set your reserve at?
- Thread starter Zorg
- Start date
We've only had our system for 2 months, so haven't had a full year of experience.
Based on some forum comments, set our reserve to 40% - and found that with full day of sun, we were able to fully charge the PowerWalls. And since have lowered the reserve in several steps down to 20%, and after several days of full sun, back to having excess energy being sent back to the grid once our 4 PowerWalls are fully charged.
The setting you use could depend upon how many PowerWalls you have and how much energy you typically use in your house.
We don't have a solar "buyback" plan, so we're not getting any value out of energy sent back to the grid.
Overnight, our house tends to draw about 1KW for equipment running overnight (which excludes pool pumps, most lighting, HVAC, ...). With 4 PowerWalls, 20% reserve would provide us around 10 KWH of power, or enough to run our house for 10 hours with just basic devices running, shorter if we have air conditioning running.
Since we want to minimize how much energy we're sending back to the grid, we're willing to live with a minimum of 20% PowerWall charge.
Based on some forum comments, set our reserve to 40% - and found that with full day of sun, we were able to fully charge the PowerWalls. And since have lowered the reserve in several steps down to 20%, and after several days of full sun, back to having excess energy being sent back to the grid once our 4 PowerWalls are fully charged.
The setting you use could depend upon how many PowerWalls you have and how much energy you typically use in your house.
We don't have a solar "buyback" plan, so we're not getting any value out of energy sent back to the grid.
Overnight, our house tends to draw about 1KW for equipment running overnight (which excludes pool pumps, most lighting, HVAC, ...). With 4 PowerWalls, 20% reserve would provide us around 10 KWH of power, or enough to run our house for 10 hours with just basic devices running, shorter if we have air conditioning running.
Since we want to minimize how much energy we're sending back to the grid, we're willing to live with a minimum of 20% PowerWall charge.
I am in self powered mode, since I also currently get 1:1 net metering under my current SCE plan, which is a regular tiered rate (more you use, more it costs, not time of use). I have my reserve set to 35% which is enough for the powerwalls to provide me power through the night if there is a power outage while I am asleep. When I notice there is going to be rain, or high winds, I move the reserve up to 45-50%, to ensure that I would still have power if there was a power outage during that rainy day.
Im still in the honeymoon phase of looking at the energy flows all the time, so I am still enjoying somewhat micro managing the switch for rain etc to a higher reserve. It is just a couple of clicks in the app, and I have not had an issue with "settings not taking", they apply almost instantly (but my gateway is connected via ethernet).
Im still in the honeymoon phase of looking at the energy flows all the time, so I am still enjoying somewhat micro managing the switch for rain etc to a higher reserve. It is just a couple of clicks in the app, and I have not had an issue with "settings not taking", they apply almost instantly (but my gateway is connected via ethernet).
jrweiss98020
Tessa's Tesla
Set it low enough that you can get through the high-cost period on a daily basis, and high enough that you can fully recharge during the low-cost period if possible. You might have to adjust some, summer to winter.
I use 80% winter (to provide backup in case of storm outage) and 50% summer.
I use 80% winter (to provide backup in case of storm outage) and 50% summer.
Dukeybootie
Member
I am also in the honeymoon phase (less than 2 weeks in) so I am micromanaging and experimenting constantly. With 2 Powerwalls and 20 panels, I set the reserve at 80%. My goals:
-send as much solar to the grid as possible to rack up credits (SCE, NEM 1.0, TOU-D-A for a few more months)
-be self-powered (absolutely no grid use) until 10pm when super off-peak starts
-only use grid power from 10pm-8am (super off-peak)
-meet minimum SGIP requirements
So far everything is working exactly as I would like. I am in self-powered mode. Changing the reserve % only takes a minute or two to register and there are no strange behaviors being exhibited. I can easily make it to 10pm with an 80% reserve setting and the Powerwalls charge up to 100% well before noon the next day, which leaves plenty of time to rack up solar generated credits for the rest of the day. I am a happy customer =)
-send as much solar to the grid as possible to rack up credits (SCE, NEM 1.0, TOU-D-A for a few more months)
-be self-powered (absolutely no grid use) until 10pm when super off-peak starts
-only use grid power from 10pm-8am (super off-peak)
-meet minimum SGIP requirements
So far everything is working exactly as I would like. I am in self-powered mode. Changing the reserve % only takes a minute or two to register and there are no strange behaviors being exhibited. I can easily make it to 10pm with an 80% reserve setting and the Powerwalls charge up to 100% well before noon the next day, which leaves plenty of time to rack up solar generated credits for the rest of the day. I am a happy customer =)
installed 2PW in Jan, was doing the TOU for a few weeks. Switched to self gen 20% after reading more up on the forums. I'm at 38 solar panels so I can crank up to 12.54 kW so I now charge my cars during the day when suns up so I dont suck the walls dry and let solar dump into them. If you need to charge overnight, try to schedule it like 4am so if the wall gets low sun will be up right as it hits the 20% limit.
If you're on a net metering/solar buyback plan, the strategy for setting reserve % will be different. When the PowerWalls are full, you get energy credits when excess power is sent to the grid, which will cover electricity costs when the PowerWalls are at the reserve % (overnight or during cloudy days). The reserve % should be set to provide enough power to handle expected outages (2 to 8 hours?), and the setting probably will have little impact on your electricity bill.
But if you're not on a net metering/solar buyback plan, then when the PowerWalls are full. excess power sent to the grid is wasted because you don't get a credit for that excess power. This is where setting the reserve % could have a significant impact on the electric bill - if you set the reserve % too high and end up sending a lot of excess power to the grid. The trade-off is have less power available for unplanned outages.
We're in Texas, which doesn't require utilities to buyback solar power. For our new solar/PW system, there are 3 basic electric plans we can get.
The cheapest is a straight cost per KWh (currently $.091) - under that plan we have reduced our electric bills by about 50% compared to before the solar/PW installation. Under this plan, we want to minimize how much excess power is sent back to the grid - which is why we're now have reserve at 20%.
A solar buyback plan currently runs $.149 per KWh - buying back excess power at the same rate we would purchase power from the grid. Going onto this plan would allow us to increase the reserve %, but would likely end up increasing our electric bill by 60% (losing most of the savings from going solar).
The other option is a "free" nights plan, with free electricity overnight and electric rates running $.191 to $.22 per KWh for daytime electricity. Based on usage so far, by using the stored PowerWall energy only during the daytime hours, it appears we could cut our electric bills another 50% (a total savings of 75% compared to pre-solar), by setting the reserve % to try to minimize how much electricity we're pulling from the grid during daytime hours. And if we're able to get close to zero grid power during the day (except for very cloudy days)k, we might be able to increase the reserve % to provide more power during an unplanned outage.
We're up for renewal on our current plan in June - and will be pulling the smart meter data for actual electricity usage to determine which electric plan we'll use next.
So for those trying to figure out what reserve % you should use - if you have options on the type of electric plan you can use - you may also want to look at that in addition to adjusting the reserve %.
But if you're not on a net metering/solar buyback plan, then when the PowerWalls are full. excess power sent to the grid is wasted because you don't get a credit for that excess power. This is where setting the reserve % could have a significant impact on the electric bill - if you set the reserve % too high and end up sending a lot of excess power to the grid. The trade-off is have less power available for unplanned outages.
We're in Texas, which doesn't require utilities to buyback solar power. For our new solar/PW system, there are 3 basic electric plans we can get.
The cheapest is a straight cost per KWh (currently $.091) - under that plan we have reduced our electric bills by about 50% compared to before the solar/PW installation. Under this plan, we want to minimize how much excess power is sent back to the grid - which is why we're now have reserve at 20%.
A solar buyback plan currently runs $.149 per KWh - buying back excess power at the same rate we would purchase power from the grid. Going onto this plan would allow us to increase the reserve %, but would likely end up increasing our electric bill by 60% (losing most of the savings from going solar).
The other option is a "free" nights plan, with free electricity overnight and electric rates running $.191 to $.22 per KWh for daytime electricity. Based on usage so far, by using the stored PowerWall energy only during the daytime hours, it appears we could cut our electric bills another 50% (a total savings of 75% compared to pre-solar), by setting the reserve % to try to minimize how much electricity we're pulling from the grid during daytime hours. And if we're able to get close to zero grid power during the day (except for very cloudy days)k, we might be able to increase the reserve % to provide more power during an unplanned outage.
We're up for renewal on our current plan in June - and will be pulling the smart meter data for actual electricity usage to determine which electric plan we'll use next.
So for those trying to figure out what reserve % you should use - if you have options on the type of electric plan you can use - you may also want to look at that in addition to adjusting the reserve %.
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