Next Power Outage

This story caught my eye a few days ago:  Tesla has a home battery to sell you, with or without solar

Tesla said this week that it’s now selling Powerwalls separately “in select US markets.” The company hasn’t put out an official list of these markets (as far as we can tell), but Tesla’s website offers a way for prospective shoppers to check if they live in an approved spot. For example: I typed in my Los Angeles address, and Tesla’s site responded: “We’re assessing where to service next. Reserve your Powerwall to help us expand into your area.” However, the standalone device is available in other areas, such as Austin, Texas.

Harri Weber | TechCrunch | March 14, 2023

I checked our Washington County, Pennsylvania address and got the same message. There could still be a Tesla warehouse in Emsworth, PA and there are now two Tesla car dealerships in the Pittsburgh area, so you would think our area would be at the front of the line.

BACKUP BATTERY ADVANTAGES

There’s no doubt that home backup batteries are expensive, so what are the advantages?

• They allow you to be off-grid during a power outage. In other words, as long as there’s a charge on the battery, or your solar panels are producing energy, your lights will stay on. Powerwall2 battery systems are typically designed to cut-off heavier electricity loads during a power outage, like air conditioning and an electric clothes dryer, to conserve battery storage life.
• If you have solar panels without a backup battery, your house will go dark along with your neighbors during a power outage, since you can’t put energy back on the grid at that time, in order to protect utility company linemen who are working on the outage.

Powerwall2 smart phone app

SOLAR PANELS WITH OR WITHOUT A BACKUP BATTERY

The PW2 can be set to store 100 percent of its charge for outages, or set to any amount between zero and 100 percent. Since the PW2 has a temperature maintenance system, I’ve noticed that it loses 3 percent of its storage overnight inside the garage. Outdoor installations will likely be different in cold climates. Some electricity markets have variable rates according to the time of day, so there are further PW2 software settings to use stored electricity to its best advantage, as well as having other settings like a Storm Warning, which is designed to fully charge the battery ahead of bad weather. 

Most of the numbers I’ve seen quoted lately indicate the Return on Investment (ROI) for a rooftop solar panel system these days is around 10-years. If you add a battery, or three, that ROI lengthens considerably. Wednesday was a perfect day for solar energy production: Cool & Sunny!

Rooftop solar panel production total: 39.3 kWh
(Above) Front roof — (Below) Back roof

THE FUTURE OF HOME BATTERY BACKUP

We’re now seeing electric vehicles (EVs) that can not only be charged from home solar panels and the grid, but also work in reverse to provide battery backup during a home power outage. There certainly appear to be price advantages when comparing the cost of the number of PW2’s needed to provide the same amount of storage as an EV battery.

To fully compare the two alternatives would require a tax professional. Using speculation, and painting with a broad brush, the EV could earn a $7,500 federal tax credit, while the PW2 could earn a 30 percent federal investment tax credit. Check the actual facts as they would apply to your peresonal situation, and keep in mind that a federal tax credit, while it may be possible to carryover to future tax years, needs federal tax liability to offset it.

I’m not up to date on the EV federal tax credits and/or state EV rebates, but do believe that in the past, an EV tax credit could only be used in the same tax year, with no carryover. I’m not an attorney or CPA, so look into the current details yourself, before making any decisions or purchases.

WHAT MIGHT HOME BATTERY BACKUP BE LIKE WITH AN EV?

For some back-of-the-napkin number crunching, let’s assume the current Chevy Bolt, with a 65 kWh battery, could provide home battery backup (which it cannot) and compare that vehicle cost to buying an equivalent number of PW2’s, to provide the same amount of battery storage capacity. Many factors would surely change these numbers, like having to upgrade the home electrical system to dovetail with its new capabilities.

On the Tesla website Wednesday, they were quoting $9,200 for one PW2 installed, and $8,000 for each additional PW2. If you were adding PW2’s to an existing PW2 system, the first battery was $1,000 less, with the same $8K cost for additional ones. In mid-2018, the first PW2 installed was $7,500 so prices have gone up.

The MSRP for a 2023 Chevy Bolt LT with the base level trim and options is around $27,500. There are taxes and other fees, and some dealers I checked on the west coast have added another $6K to $7K to the MSRP!

Back-of-the-napkin imaginary battery comparisons, just for fun: 

The Chevy Bolt has a 65 kWh battery
Tesla PW2 has a 14 kWh battery

65 divided by 14 = 4.6 times more battery capacity in the Bolt

First PW2 = $9,200
Add 3.6 more PW2s = $28,800
Total for an imaginary 65 kWh battery capacity = $38,000

2023 Chevy Bolt LT1 MSRP = around $27,500

Bottom line scenario, using oversimplification, just for our imaginations:

You get the same amount of battery capacity, along with a car, for $10,500 LESS!

Again, not hard and fast numbers, but you get the point on potential battery cost comparisons.