It won’t. It has batts. All batts die with cycles and die quicker if they are deeply cycled. It is a nice package and much easier for folks to purchase and install. But it isn’t good for much IMHO.
From: Eric Kuhnke Sent: Wednesday, March 23, 2016 9:48 PM To: [email protected] Subject: Re: [AFMUG] Tesla 7kWh powerwall as UPS? The thing is... Calculating lead acid batteries as 30 or 15 cents per kWh to purchase doesn't take into account lifecycle cost. If the lead acid batteries are only good for 800 to 1000 cycles, absolute maximum, and the competing battery option is twice as expensive but lasts for 4000 or 5000 cycles, the more expensive option actually costs a great deal less. It remains to be seen whether the powerwall will really hold up to thousands of cycles. On Wed, Mar 23, 2016 at 8:45 PM, Chuck McCown <[email protected]> wrote: 7/5=1.4 hours at full load. Batts are about 30 cents per watt hour for AGM, half that for flooded cells. Inverters are about 25 cents per watt. 7kWh battery == $1125 –$2250 5 kW inverter == $1250 Put it on your critical loads. Charge the batts with a rectifier that is fed from commercial power. You can run the inverter all the time, or use a smaller charger and put in a transfer switch. Transfer switches/contactors are not very expensive. One single relay will do the job. From: Eric Kuhnke Sent: Wednesday, March 23, 2016 7:45 PM To: [email protected] Subject: [AFMUG] Tesla 7kWh powerwall as UPS? $3000 is not so bad for something that can deliver up to 5kW for multiple hours... http://arstechnica.com/business/2015/09/tesla-powerwall-home-installations-are-starting-for-pilot-customers/ I am interested to see the results of integrating two of these in parallel with an off grid solar array. At first glance it appears a great deal less expensive than buying a dozen 12V 200Ah lead acid AGM batteries to make a string. And should last a lot longer in 60% cycle depth daily cyclic use. Interesting they've cancelled the 10kWh model ($3500) which had a much shorter lifespan, the 7kW model is rated at 5000 cycles.
