A realistic look at the Tesla Powerwall

So what is all the hype about the Tesla Powerwall?

Is it really anything new or just a redesign of what is already out there? Is it new technology or just new packaging?

Let’s take a fresh look at the Tesla Powerwall specs…

  • Telsa 10 kw Powerwall
  • Lithium-ion
  • Quantity 1
  • 10 kilowatts of stored power = $3,500.00, not including shipping
    • (Update: 14 kilowatts of stored power = $14,000 – $16,000, not including shipping 10/20)
  • 350 – 450 volts
  • 8 – 8.6 amps
  • 10 year warranty

Out with the old… The T-105’s are being retired.

Here are the specs of my personal battery bank I currently live with in my off grid home.

  • T-105 6 volt battery
  • Lead acid
  • Quantity (12)
  • 16.2 kilowatts of stored power = $1,860.00*, not including shipping
    • (Update 16.2 kilowatts of stored power = $2,148, not including shipping 10/20)
  • 24 volt system
  • 675 amps
  • 1 year warranty

If you are deciding to create an off grid home, money is usually an issue. Actually, usually money is an issue in all occasions to some degree, but most customers want the most they can for their dollar. At this point, the old lead acid battery technology still provides more for the dollar than the Tesla Powerwall. Personally, I think it is great what Eon Musk is trying to do, but is his technology ready for the mass market?

After watching the documentary Revenge of the Electric Car, I suspect Tesla may be jumping the gun slightly since it has not yet proven its battery technology on the open market. 10 kilowatts is not that much power for the price. Sure, it’s lithium-ion versus lead-acid, but the numbers don’t add up. Currently, my battery bank has turned 4 years of age and with proper maintenance these past few years, they still are functioning in their prime. I am predicting I will have 10 years on them easily, which gives Tesla at least 6 years to prove their batteries on the open market. (Update: The T-105’s lasted 7 years) The only item on Telsa’s list is the warranty, 10 years, which is great. A person could buy the Tesla Powerwall for “peace of mind”, but if they need to use the warranty, they are without power until Tesla approves the replacement.

How much stored power could I have if I bought $14,000.00 of lead acid 6 volt batteries?

I have a 24 volt system, meaning I currently have four, 6 volt batteries in one string to make 24 volts. I have 3 strings of batteries, 4 batteries in each string which equals 12 batteries total. If I spent $2,150.00 on the Trojan T-105 batteries, I would have 3 strings or 12 batteries. (Update: 3 strings is the max recommended size for a battery bank) My storage capacity would be an amazing 16.2 kilowatts of power almost equal to the  Tesla Powerwall, now that puts stored battery power into proper perspective with a 12,000 dollar savings.  If I replace my bank every 7 years, I could have a fresh battery bank for over 30 years, which would equal one Tesla Powerwall for 10 years.

*price at Backwoods Solar at $155.00 per battery, not including shipping (Update: T-105 Battery price is now 179.00 each as of 10/20.)

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