Did you notice the operating temp is up to 110F? That kind of rules it out for Arizona summers.. (and probably many other places in the southwest)
Rules out Texas too. I'm actually surprised it's so low.
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Did you notice the operating temp is up to 110F? That kind of rules it out for Arizona summers.. (and probably many other places in the southwest)
Rules out Texas too. I'm actually surprised it's so low.
I'm also in the "how will this work with my microinverters" camp. I have 36 250W panels with Enphase microinverters (9kW DC, 8.1kW AC).
I don't have net metering (I'm on a municipal power company, so they are exempt from the net metering laws), or TOU (also not offered). I buy power for $0.143/kWh, and sell for $0.053/kWh (sort of a reverse TOU, since I'm incented to use my own power during the day).
I think I'd want some sort of charger/inverter that can measure my net inflow/outflow, and dynamically scale up/down charging or inverting depending on flow into/out of the house. Others may want to add some sort of scheduling to prioritize based on TOU rates.
Rules out Texas too. I'm actually surprised it's so low.
It wasn't clear in my prior post, but the micro inverters are sort of a must-have for me. If I'm forced to pick PowerWall and switching to string inverters or sticking with my existing setup, the status quo wins.I would think the smart inverter would basically feed your house with PV directing the excess to the battery while simultaneously isolating you from the grid. At night, it would draw from the battery until depleted. Once depleted by too much usage overnight or a rainy day, it would transfer seamlessly to the grid ala UPS style.
As you point out, this scenario precludes using micros...... Still, I'd change my system in a heartbeat if I could use a cost effective salvage MS battery (or Tesla's third generation cost effective PW) even if it does cause me to loose the efficiency of the micro inverters.
It wasn't clear in my prior post, but the micro inverters are sort of a must-have for me. If I'm forced to pick PowerWall and switching to string inverters or sticking with my existing setup, the status quo wins.
That's because I have a multi-level roof, with a due southern exposure. My garage is on the east side of the house, and the family room on the west side. Both of these sit lower (maybe 6-8 feet; it's hard to tell from the ground) then the main roof. In the morning and evening, some of the panels on these lower side roofs are in shade. With micro inverters, I only lose those panels. With string inverters, I'm going to loose a lot more of my morning and evening production.
Maybe I can find a junkyard S charger? Hmmm...
It wasn't clear in my prior post, but the micro inverters are sort of a must-have for me. If I'm forced to pick PowerWall and switching to string inverters or sticking with my existing setup, the status quo wins.
Regular panels are wired in strings. It is easy enough to figure out which areas will be shaded, and wire them together, so the shade only knocks out one section. Microinverters work well, too, but string inverters can work just fine if you are able to think a little bit about shading ahead of time.
Well yeah, if you only consider Outdoors Installations.
But there are places that don't go to 110. Like every enclosed inhabited space (since this gadget won't kill you indoors like a Gasomoline Genset would).
It wasn't clear in my prior post, but the micro inverters are sort of a must-have for me. If I'm forced to pick PowerWall and switching to string inverters or sticking with my existing setup, the status quo wins.
That's because I have a multi-level roof, with a due southern exposure. My garage is on the east side of the house, and the family room on the west side. Both of these sit lower (maybe 6-8 feet; it's hard to tell from the ground) then the main roof. In the morning and evening, some of the panels on these lower side roofs are in shade. With micro inverters, I only lose those panels. With string inverters, I'm going to loose a lot more of my morning and evening production.
Maybe I can find a junkyard S charger? Hmmm...
Wouldn't work in my situation - say I break the system into 2 strings, 4.5kW each, and feed 2 5kw inverters. I still loose an entire string in early afternoon when one panel on the garage closest to the house goes into shade. The only way to stop that, and continue getting power out of the rest of the array is to put the shaded panel into a string of 1, ie, give it a micro inverter.Regular panels are wired in strings. It is easy enough to figure out which areas will be shaded, and wire them together, so the shade only knocks out one section. Microinverters work well, too, but string inverters can work just fine if you are able to think a little bit about shading ahead of time.
The issue is that a shaded panel blocks the current flow through the string, cutting the output of the entire string. I quickly scanned a Solar Edge tech note that seems to imply the optimizers can deal with some amount of shading, but I couldn't tell how much/how well at first glance. But it is an interesting way to approach the problem.Couldn't you use the Solar Edge system and get everything you need? That hybrid system has "optimizers" that manage each panel independently, and feed DC to a simple bulk inverter. Solar Edge partnered with Tesla on this stuff, so it looks like it would work well. How to supply power when the grid is down would still be an issue, tho.
PS. Is there any info on the thermal management system? Liquid with pump, radiator an fan built into each 10 kWh unit? Air cooled with just a fan? What are the fan specs and how long will it live?
No, Elon said in the press conference before the event that the cells are different, but he didn't elaborate.I haven't studied the Powerwall as much as I might have (it wouldn't do anything for my situation). Do we absolutely know that it uses the same cells as the car, or is this just an assumption?
If so, I guess I'm confused -- I thought a major contributor to the low production for the Model S was a shortage in the supply of batteries. Why find another product that uses up the same cells? I can understand if the Gigafactory is operational and there are batteries in abundance, but why use up the current supply even further? I've heard that home storage could be a use for used batteries, but I don't think that is happening here...
I wondered about that too. But given the PowerWall Specs show the storage and discharge operating temp ranges as being within the specs for a typical Li-ion chemistry, I wonder if it only has a heater in it to address the need for bringing the cells up to the warmer charging temp?
Looking at the specs again I see "liquid thermal control" is mentioned. That would require a pump, but maybe only a resistive heater with no radiator or fan, for the reasons you mentioned. At 0.2C the cells should not heat up much past ambient.
GSP
How does the powerwall connect to an existing PV system and if you are on TOU and store power at peak times in the powerwall do you lose the peak credit that your system is generating because it is going into the storage unit?
Looking at the specs again I see "liquid thermal control" is mentioned. That would require a pump, but maybe only a resistive heater with no radiator or fan, for the reasons you mentioned. At 0.2C the cells should not heat up much past ambient.
GSP