As most of you know Tesla anounced the Powerwall Home Energy Storage batteries to be released sometime this Summer in two models. A 7 Kwh version for Grid Tide Load Shedding, and a 10 Kwh UPS straight Battery Inverter for emergency stand by use. The specs were very misleadinf leaving more questions than answers. Got my curiosity up so did some searching on Tesla Forums and EV forums and got some details, useful details along with follow up PR releases from Tesla and Musk Twitter account. So here is what is known and some of my comments.
Input Requirements: 180 to 300 volts AC 5 amps circuit operating at 50/60 Hz. This makes is compatible with any countries electrical architecture. Although a 5 amp circuit at 240 VAC in the USA is unheard of as I do not know of any 5 amp dual pole 240 amp breakers on the market. 240 volt circuits are for large loads not small loads of 1000 watts the charger uses. None the less doable but a special order product.
Nominal Battery Voltage and AH Capacity: 390 volts @ 25 AH for both 7 Kwh and 10 Kwh models. Battery chemistry unknown Lithium at time of writing. Strongly indicates a 108SxP Lithium battery meaning of at least 108 cells give or take up to 5 cells depending on which cathode/anode material they are using from Panasonic. Possible up to 3 parallel strings making it 216 to 314 cells. Best guess is same battery type the Tesla Mega Factory will be producing licensed from Panasonic. The only difference between the 7 Kwh and 10 Kwh models are firmware in the controller limiting how much energy is accessible by the users.
What Comes Inside The Magic Box: 2 Amp AC 390 Volt DC Power Factor Corrected Charger, BMS, and Liquid Thermal Management with both heating and cooling. OK charger and BMS are no surprise here to anyone except one noted feature. You must provide an Internet connection so Tesla can monitor you. Some people are not going to like that very much. The guise or justification is it can be made to use as a microgrid giving up control to someone else. What was a surprise is Thermal Management for such a low density energy battery. Normally that is only required when high energy density cells are combined with high charge and discharge rates to prevent thermal runaway and resulting fires that come with it. Unfortunately Tesla has not published any specifications on how much energy the thermal management uses. Only thing known is it uses pumps, fans, and an electric heating element. All of it mechanical subject to mechanical failure and uses unspecified power. Only thing that makes sense is to keep the batteries at optimum operating temperatures fo maximum power capacity in both cold and hot climates. My take Red Flag.
Output: 350 to 450 Volts DC At a maximum of 6 amps (2 Kw) continuous, and 8 amps burst (3 Kw) for unspecified amount of time. OK this is where a lot of questions come in play. What are you the consumer suppose to do with that? You cannot take it to your Grid Tied Inverter because it is made to use a Current Source, not a voltage source of a battery. It can go to a Battery Inverter if you could find one that operates from 350-450 volts. You could also send it to a Hybrid Inverter is one actually existed. Rumor has it that is the next announcement from Tesla offering a line of Hybrid and Battery Inverters. Absolutely Brilliant, create a monopoly market for your product.
Price Point & Distribution: The 7 Kwh is listed at $3000 and the 10 Kwh is listed at $3500. Both units are the exact same thing, only firmware is different. OK the price is completely BOGUS and good ole fashion Bait and Switch Marketing. Just no nice way to say it. The battery is only available through certified Installation Contractors. Solar City has been named as one of them and their contractor must install the system. Bloomberg reports just to get the battery installed is $7000 and higher. It is speculated Musk is trying to create a monopoly market offering a battery only his company makes Inverters and interface equipment to work with it. At least initially until other manufactures can com eup with some products. But for now Tesla has the whole market exclusively including the distributors and installation. Absolutely brilliant IMHO, reminds me of Rockefeller with Standard oil and Bill Gates with MS
Input Requirements: 180 to 300 volts AC 5 amps circuit operating at 50/60 Hz. This makes is compatible with any countries electrical architecture. Although a 5 amp circuit at 240 VAC in the USA is unheard of as I do not know of any 5 amp dual pole 240 amp breakers on the market. 240 volt circuits are for large loads not small loads of 1000 watts the charger uses. None the less doable but a special order product.
Nominal Battery Voltage and AH Capacity: 390 volts @ 25 AH for both 7 Kwh and 10 Kwh models. Battery chemistry unknown Lithium at time of writing. Strongly indicates a 108SxP Lithium battery meaning of at least 108 cells give or take up to 5 cells depending on which cathode/anode material they are using from Panasonic. Possible up to 3 parallel strings making it 216 to 314 cells. Best guess is same battery type the Tesla Mega Factory will be producing licensed from Panasonic. The only difference between the 7 Kwh and 10 Kwh models are firmware in the controller limiting how much energy is accessible by the users.
What Comes Inside The Magic Box: 2 Amp AC 390 Volt DC Power Factor Corrected Charger, BMS, and Liquid Thermal Management with both heating and cooling. OK charger and BMS are no surprise here to anyone except one noted feature. You must provide an Internet connection so Tesla can monitor you. Some people are not going to like that very much. The guise or justification is it can be made to use as a microgrid giving up control to someone else. What was a surprise is Thermal Management for such a low density energy battery. Normally that is only required when high energy density cells are combined with high charge and discharge rates to prevent thermal runaway and resulting fires that come with it. Unfortunately Tesla has not published any specifications on how much energy the thermal management uses. Only thing known is it uses pumps, fans, and an electric heating element. All of it mechanical subject to mechanical failure and uses unspecified power. Only thing that makes sense is to keep the batteries at optimum operating temperatures fo maximum power capacity in both cold and hot climates. My take Red Flag.
Output: 350 to 450 Volts DC At a maximum of 6 amps (2 Kw) continuous, and 8 amps burst (3 Kw) for unspecified amount of time. OK this is where a lot of questions come in play. What are you the consumer suppose to do with that? You cannot take it to your Grid Tied Inverter because it is made to use a Current Source, not a voltage source of a battery. It can go to a Battery Inverter if you could find one that operates from 350-450 volts. You could also send it to a Hybrid Inverter is one actually existed. Rumor has it that is the next announcement from Tesla offering a line of Hybrid and Battery Inverters. Absolutely Brilliant, create a monopoly market for your product.
Price Point & Distribution: The 7 Kwh is listed at $3000 and the 10 Kwh is listed at $3500. Both units are the exact same thing, only firmware is different. OK the price is completely BOGUS and good ole fashion Bait and Switch Marketing. Just no nice way to say it. The battery is only available through certified Installation Contractors. Solar City has been named as one of them and their contractor must install the system. Bloomberg reports just to get the battery installed is $7000 and higher. It is speculated Musk is trying to create a monopoly market offering a battery only his company makes Inverters and interface equipment to work with it. At least initially until other manufactures can com eup with some products. But for now Tesla has the whole market exclusively including the distributors and installation. Absolutely brilliant IMHO, reminds me of Rockefeller with Standard oil and Bill Gates with MS
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