The Tesla Powerwall: Is It Really Worth It?

There has been a lot of buzz surrounding the Tesla Powerwall battery. The Tesla Powerwall is arguably the most well-known solar battery for homes, but does it live up to the hype? Why does everyone want this battery? Is it really worth it? How does it stack up against its’ competitors? Here at Solar Professionals, we have created this review guide to help you decide if the Tesla Powerwall is a solar battery worth investing in.

What is the Tesla Powerwall?

The Tesla Powerwall is an integrated lithium-ion home battery system that stores solar energy for backup protection, solar-self consumption, or increased energy dependence. The Powerwall is most often associated with storing energy generated by solar panels; however, you can actually charge these batteries with an electricity source to use as backup power during an outage. Additionally, you can stack up to 4 Powerwall units together to form a large energy storage, making them a viable option when powering small and medium-sized businesses as well as homes.

The Tesla Powerwall can be purchased in two variants: the Powerwall 2 and the Powerwall+. Both variants have the same storage capacity, but the Powerwall+ includes a microinverter for seamless integration with solar PV panels. The Powerwall+ can also deliver more power when in direct sunlight, while the Powerwall 2 offers the same output regardless of solar generation.

Who Are Solar Batteries Designed For?

There are three main types of solar battery users: those who want energy independence, those who want to lower their energy bill, and those who are looking to minimize their home or businesses’ carbon footprint.

Energy Independence – Those who want energy independence are looking to rely less on their utility company. Your home is connected to your utility company’s power grid, and, in an ideal situation, you have power 100% of the time. Unfortunately, having power 100% of the time is hardly ever the case. Power outages can happen for a number of reasons, but since the Powerwall and its alternatives allow you to store solar energy, they also reduce your reliance on your utility company.

Reducing Electricity Bill – You will see an immediate impact on your energy bill when you switch to solar. During the hours that the sun isn’t shining, solar batteries give you the ability to run your home off of stored energy, further boosting savings!

Minimizing Carbon Footprint – Switching to solar panels is just the first step in reducing your carbon footprint. Adding on the numerous solar energy storage capabilities that a solar battery offers decreases the need for fossil-fuel electricity even further.

Comparing the Powerwall to Its Competitors

When comparing options for home batteries, there are a few key metrics to keep in mind: price, usable capacity, continuous power, and warranty terms. The table below gives you a side-by-side comparison of the Powerwall and its competitors.

 Tesla PowerwallEnphase IQ 10Generac PWRcell
Price $$8,000 – $10,000$6,000 – $8,000$9,000 – $15,000
Stated Capacity13.6 kWh10.1 kWh18 kWh
Usable Capacity10.88 kWh10.1 kWh14.4 kWh
Continuous Power5.0 kW5.7 kW9.0 kW
Warranty10 Years10 Years10 Years

All three solar battery options are relatively close in price with the Generac PWRcell being the most expensive on average and they each have a 10-year warranty. While they each have these similarities, they differ in stated capacity, usable capacity and continuous power.

Competitive Differences

The Tesla Powerwall and Generac PWRcell use a Panasonic battery cell with a Lithium/Cobalt blend. This battery chemistry is more volatile (resulting in thermal runaway concerns) and only has an 80% depth of discharge. That means it can only utilize 80% of its stated capacity to power your home before it has to protect itself and recharge.

While Enphase chose a 10.1 kWh format, they are using a Lithium/Ferro Phosphate blend (or iron-phosphate). These batteries are much more temperature tolerant, can discharge 100% of their capacity with no concern about recharging, and they only use 15% as much Lithium in the chemical makeup of that cell. Therefore, you stretch our already taxed supplies of lithium to create more energy for cars and homes using battery technology.

When referencing ‘continuous power’ it is important to understand that in the Tesla Powerwall and Enphase batteries the numbers are calculated per battery unit (both allow 4 battery units to be stacked). With Generac it is total output regardless of capacity. Generac can flex from 6 kWh of total storage to 36 kWh total, but it always has a 9.0 kWh discharge rate (or about 50 amps).

Tesla and Enphase have approximately 20 amps per unit and increase as you add battery units – 2 units give 40 amps, 3 units 60 amps, etc. Generac has 3.3 kWh battery cells and can handle 6 per cabinet. With a limit of 2 full cabinets per inverter/controller.

What Battery Should I Purchase?

The best battery for your home is completely based on preference. The Generac battery is by far the least expensive by comparison as it takes 2 Powerwall units or 2 Enphase units to equal the performance. But both the Enphase and Generac batteries support load shedding, and support drawing power directly from your solar panels and the batteries simultaneously – Tesla cannot manage that feat! Contact The Solar Professionals today with any questions related to solar battery options. One of our trained professionals is always happy to help!

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