Tesla Powerwall 2

Image source: Tesla

The Tesla Powerwall has changed the way people talk about solar batteries and home energy storage from being a conversation about the future to a conversation about now.

In the humble opinion of this SolarReviews writer, it is currently the best solar battery and smart energy storage solution on the market. I would love to say it wasn't (because I love to promote small independent solar companies and solar products) but credit where credit is due, the new Tesla Powerwall kicks ass.

What 5 factors make the Tesla Powerwall solution stand out as the best current solar battery storage solution for residential energy storage?

  1. Cost at around $7,500 installed for 13.5 kWh of usable storage this is relatively good value given the high cost of solar energy storage. Still not an amazing return but better than its peers;
  2. Inbuilt battery inverter and battery management system now included in the cost. With many other solar batteries the battery inverter has to be purchased separately;
  3. Battery Quality- Tesla has partnered with Panasonic for its Lithium-Ion battery technology meaning the individual battery cells should be very high in quality.
  4. Intelligent software controlled architecture and battery cooling system. Although I am not an expert on this it appears to me that Tesla is leading the pack in terms of controls to ensure both safety and smarter functionality; and
  5. Time-based controls allow you to minimize the cost of electricity from the grid over a day when you face time of use electricity billing. Although others have talked about being able to do this no one else has shown me a slick app on my phone to set peak and off-peak times and rates and to have the battery work to minimize my cost as the Powerwall can do.

However, one may ask why someone would buy a solar battery when their utility offers net metering? Net metering gives a credit for excess power sent to the grid so in effect this policy does economically what a solar battery does physically…. it provides relief from having to pay for power when your solar panels are not producing by storing excess electricity generated during the middle of the day.

Although net metering is under attack from utility company lobbyists it is still available in more than 30 states as at August 2018 and if you buy a solar system while the policy exists you are guaranteed the benefit of retail value for your excess power for between 10-20 years (depending on the net metering rules in your state).

So why would you pay for a solar battery when you have access to net metering for free?

The answer is a combination of three factors being:

  • The rise of time of use electricity rate plans from utilities;
  • Government incentives in key states like California; and most importantly
  • The Tesla Powerwall now offers time-based control…(and it's awesome)

What are Time-of-use electricity rate plans making the Powerwall more popular?

Time of use electricity rate plans are schedules of rates charged for electricity by utility companies where more is charged for power during peak times and less is charged for power during off-peak times. These plans are becoming popular with public utilities commissions around the country as a way to discourage the use of power at peak times and in doing so.

You can find out if your utility offers a time of use electric rate plan that may be cheaper for you.

The difference in pricing can be significant. For example, on the cheapest PG&E rate plan during the summer months the off-peak power charge is $0.26 cents but during peak hours the charge is $0.36 cents.

This type of billing by utilities will become more and more common and already in California time of use billing will be mandatory for residential customers of investor-owned utilities by the end of 2019.

Is Tesla Powerwall the best solar battery?

Put simply, because none of the other mainstream home energy storage solar batteries offer time-based control of charging and discharging (or at least as elegantly as the Powerwall does) none of the other solutions.

The Powerwall allows you to set into the app on your phone that controls it the peak and off-peak times and rates of your utility. It will then use both excess solar power and grid power to make sure the battery is fully charged at the end of off-peak times so that you can use as little power as possible during the expensive peak time. Kudos Tesla engineers...kudos.

Tesla App

Image source: Telsa Powerwall

What incentives are available to include battery energy storage with your solar system?

In preparing this article, I attempted to use the dsireusa.org incentives database but it was hard to find any definitive list of solar energy storage or solar battery specific incentives. The difficulty in this research lies in the fact that energy storage may or may not be eligible for energy efficiency grants, tax credits or rebates of which there are literally thousands of programs around the country.

Given this complexity, our suggestion would be to reach out to local solar companies as they will usually know all the local incentives available. You can get an online solar savings estimate and solar quotes through Solar-Estimate.

How Much Does the Tesla Powerwall Cost?

All in, a new Tesla Powerwall 2.0 costs around $7,600 installed. With the generous rebates in some states (California, for example), the price seems good value if you live in an area with expensive power prices given the new amount of storage and control the battery can give you.

How Much Power Does It Provide?

With a storage capacity of 14-kilowatt-hour (kWh) of electricity, most experts say the average American household can break even by purchasing the Tesla Powerwall 2.0, which will release power at a constant rate of 5 kilowatts (kW), with short bursts of 7 kW.

On average, U.S. homes consume approximately 28 kWh per day, meaning the typical Powerwall 2.0 provides the perfect amount of storage to deal with nighttime electricity use.

Practically speaking, the length of time the battery will last depends on a host of variables, including how much energy was stored and how much power you use.

What Am I covered for if the Battery fails?

Tesla's 10-year warranty guarantees it will store at least 70% of its rated output over the 10 year period. It assumes the systems will store electricity daily and discharge it regularly.

Is the Powerwall worth it for your home?

Buying the Powerwall for your home makes sense in two situations:

  • Your utility does not offer net metering and instead pays you a lower avoided cost rate for excess solar energy that you send to the utility grid. Under those circumstances, harvesting excess electricity, physically storing it in a battery and then using it at night can make sense.
  • You face time of use electricity billing and you can use the battery to consume less utility power in peak times by charging it with either solar or off-peak grid power outside of peak times.

But even where these circumstances don't currently exist—two rapidly changing circumstances could significantly change the equation.

Of the 30 states that currently offer retail net metering, at least half of them are considering changing the program in some way. Some states are reducing the amount of reimbursement, while others are eliminating the program entirely. In either of those scenarios, purchasing a Powerwall 2.0 could be the right decision (although the more obviously right decision is to get quotes on a simple grid connect solar system while you can get a 10 or 20-year net metering contract.

Secondly, time-of-use electricity rates are also on the rise in an effort to smooth out electricity use and reduce use at the peak times. Time-of-use rates make power use more expensive during peak use times and less expensive during times of low grid use.

As more emphasis is placed on when the electricity is used, batteries offer consumers more control, allowing them to store their own electricity during more expensive times and use the stored power during more expensive peak hours.

In other words, Tesla's Powerwall 2.0 is beginning to make more sense than ever and, being the best battery on the market, is your best bet if you are looking for an energy storage solution.

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