My problem with the product is the lifespan. Based on my experience with the Leaf, charging and discharging means it starts losing storage capacity after 18 months. After 3 years, it’s probably going to be down to 80-90% of storage life. In 4-5 years, it’s junk. At that price, even if you have solar running all day, the savings differential between what you are able to sell with your overage and wholesale pricing against not having to buy back energy at retail pricing doesn’t make it worth it yet. I haven’t calculated the differential between always buying energy during non-peak times but I still can’t imagine the battery paying for itself. In our case though, with the Leaf, we need at least 4 of these to even break even on the energy to charge the Leaf. Then to make it worse, we are probably getting a Chevy Bolt or something else with a 60kWh battery in April next year.
Rory From: Af [mailto:af-boun...@afmug.com] On Behalf Of Bill Prince Sent: Friday, March 25, 2016 11:09 AM To: af@afmug.com Subject: Re: [AFMUG] Tesla 7kWh powerwall as UPS? That depends on what you pay for a KWH. If you're paying 15 cents per KWH, then you are somewhere in the neighborhood of 1466 KWH per month, or 48 KWH per day. We're on a sliding scale. Lower usage is cheaper (11-12 cents per KWH). Once you go over tier 3 usage it is over 30 cents per KWH. bp <part15sbs{at}gmail{dot}com> On 3/23/2016 8:48 PM, Sterling Jacobson wrote: What are you doing that uses 50 kWh/day? Is that to charge your car? That can’t be normal. I think my power bill is around $220 a month, what is my average kWh/day based on that? From: Af [mailto:af-boun...@afmug.com] On Behalf Of Chuck McCown Sent: Wednesday, March 23, 2016 9:39 PM To: af@afmug.com<mailto:af@afmug.com> Subject: Re: [AFMUG] Tesla 7kWh powerwall as UPS? 2.2 kWh Batts of that size would cost $700 1.8 kW inverter. That would cost $450 They plan to sell it for $1700. And they are not saying that this can pull the one single load for one hour. It will store about 25 cents worth of power. Tesla is 7 kWh. I use about 50 kWh/day. Tesla would run my house for 3 hours on average, but since the power consumption is not continuous, when I am actually using lots of juice it would probably last for less than an hour. From: Sterling Jacobson<mailto:sterl...@avative.net> Sent: Wednesday, March 23, 2016 8:22 PM To: af@afmug.com<mailto:af@afmug.com> Subject: Re: [AFMUG] Tesla 7kWh powerwall as UPS? I purchased one of these to play with: https://www.kickstarter.com/projects/ericclifton/orison-rethink-the-power-of-energy I’m not sure exactly how they work their magic, but you should just be able to plug it into the same power strip and it will charge, and supply power in case of an outage? All on a common 15amp 110v plug. We’ll see how it actually goes in August when I get mine. I also pre-ordered a powerwall like a year ago and haven’t heard much back from Tesla. I would probably use the powerwall in a solar setup combo if I move. It’s tempting to get a few and string them together for my office, but it would take some creative engineering to wire it in correctly on a transfer switch I think. From: Af [mailto:af-boun...@afmug.com] On Behalf Of Eric Kuhnke Sent: Wednesday, March 23, 2016 7:54 PM To: af@afmug.com<mailto:af@afmug.com> Subject: Re: [AFMUG] Tesla 7kWh powerwall as UPS? There's not a lot of technical information available about them, don't they have an integrated sinewave DC-to-AC inverter? I could be wrong but I believe they output AC. Assuming a typical installation for their target market, residential, do they require purchase of a separate DC-to-AC inverter? They're rated at 3.3kW load (AC) to power a house. On Wed, Mar 23, 2016 at 6:48 PM, Bill Prince <part15...@gmail.com<mailto:part15...@gmail.com>> wrote: Only hassle is that they are 450 volts (or in that neighborhood). Big challenge finding DC-DC converters for that, or maybe go back to battery-inverter-DC power supply design. bp <part15sbs{at}gmail{dot}com> On 3/23/2016 6:45 PM, Eric Kuhnke wrote: $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.
