Why You Need Solar Battery Power For Your Home


Solar panels are not new. But with solar power storage becoming mainstream — especially since Tesla released its Powerwall last year — it is more possible than ever to completely generate your own electricity from the sun.

And if you’re Australian, solar power is already mainstream. At least a quarter of homes in Australia have solar power.

If you’re considering a solar system for your home, then keep reading to find out what options you have with the latest solar battery technology.

Why even consider an alternative energy solution

Let’s get one thing straight.

Solar power is not the perfect alternative to fossil fuels.

At least, not if you need to store it with batteries.

As I’ll discuss below, solar batteries contain materials that are non-renewable.

And depending on the battery technology, some resources are less abundant than others. Which brings into question the scalability of these technologies.

And the cost of mining these resources could potentially be as damaging as fossil fuels.

But as of right now, there is no alternative energy solution that is 100% renewable with no impact to the environment.

And the bottom line is, fossil fuels is a finite resource that we can’t count on forever.

With the world’s population exploding, and third world countries becoming industrialized, we’re using up whatever resources we have left faster and faster.

There may be enough to last our lifetimes, but it’s unlikely to last for our children and grandchildren.

So we have to be open to all alternative options.

And in the case of solar power with storage, we have some feasible options for individual homeowners.

Even better when we can this kind of alternative energy to rebuild communities when standard options have failed, as in the case of Tesla using its solar panels and batteries to bring back much needed electricity to Puerto Rico.

Battery solutions today

Just like all technology, as it becomes more mainstream, the quality increases and the cost to manufacture comes down.

And solar batteries are no different. Prices have fallen 24% even since 2016.

So it’s more possible than ever to to own a complete solar system with storage.

Types of battery storage

There are three main types of solar batteries.

Lead acid

The technology that has been used for decades is lead acid. It has a short lifespan but is cheaper than the other types out on the market today.


A saltwater battery is a new type of technology which doesn’t contain any toxic or flammable materials. It uses a saline solution as its electrolyte.

Aquion Energy is the first company that has developed a saltwater battery for solar use.

The advantage compared to lithium ion is that the battery capacity doesn’t fall with multiple cycles of charge and depletion.

However, the power output is lower.

Lithium Ion

By far the most popular option is lithium ion, which is the same technology used in our cell phones and laptops. These batteries are smaller and more lightweight than lead acid, with longer lifespan, but they also cost more.

The main disadvantage of lithium ion is that its capacity decreases with each charge cycle. And capacity decreases even faster with higher charge rates and higher temperature.

For example, over time, the capacity of a Tesla Powerwall decreases significantly, if its warranty is any indication. The warranty 5 years into ownership drops from 5.44 kwh to 3.8 kwh, a 30% drop.

(courtesy of Aquion Energy)

Zinc Bromide

This is the newest technology on the market. The interesting thing about zinc bromide batteries is that the energy storage capacity never declines. And you can drain it 100% and it won’t suffer any consequences. It’s also non-flammable and recyclable.

However, it doesn’t match lithium ion in life cycle, efficiency, or power output.

RedFlow Technologies in Australia is the first company to deliver a commercially-available zinc bromide solar battery.

How much in energy cost could you save?

This depends on what kind of system you implement.

Fully off-grid

If you decide to go completely off-grid, that means you’re not connected to the utility company as a backup.

So you would need enough batteries to store the excess energy that your solar panels generate during the day to be able to use it at night when your panels are generating nothing.

And you would also need to account for extra storage in the event that you have a stretch of cloudy days are you’re not producing enough excess energy to store.

Depending on how much energy you use and how much direct sunlight you get, you might need anywhere from 17-42 panels. The average home uses 900kwh of electricity per month, or almost 11,000kwh per year.

Then you would also need batteries to store the excess power. For example, you would need two Tesla’s Powerwall units (total usable capacity 27kwh) for backup.

In this scenario, you would obviously not be paying for any energy usage from a utility company.

On-grid, mostly using solar power

Another option is that you can stay connected to the utility company but you still have the solar panels and batteries to mostly or exclusively use the solar power that you generate.

The good news is, if your system is generating excess power, and your batteries are topped off, you can sell it back to the utility company.

These rates aren’t anything to write home about (probably a few cents per kwh in the Bay Area), but you can feel good about contributing energy to the utility company’s customers.

Depending on how much electricity your system produces, you could theoretically not use any energy from the grid and even make a small amount from selling the excess power.

On grid, small battery

A third option is to stay connected to the grid and only maintain a small enough battery to reduce your total energy usage from the utility company.

The solar panels would power any usage during the day and top off your battery. Then the battery would be just big enough to give you enough power during peak evening hours.

It would be reasonable to significantly reduce your utility grid consumption and cost with a bare-minimum type of solar system.

Is it worth having a solar system in a cloudy climate?

Solar panels don’t produce as much electricity in cloudy weather compared to a clear, sunny day.

So is a solar system still worth having?

The short answer: yes.

SolarCity has done studies in the cloudiest climates and have determined that total annual output can still be quite significant.

In fact, a 6-kw system can produce over 80% of a household’s annual electricity usage.

In some cases, partial clouds can generate more electricity than a sunny day because of the “edge of cloud” effect. The sun hits the edge of a cloud and intensifies the sunlight, boosting the power generation.

This is a similar effect to sunlight reflecting off snow or water.

And using solar batteries to store enough power to accommodate the cloudy days should dispel any remaining concerns.

What the future holds for battery technology


Could solar batteries go mainstream? Many technology experts say yes.

But lithium ion batteries may not be the type to scale.

Lithium and cobalt, the two metal components in these batteries, are tight on supply. Cobalt even more so than lithium.

Gel zinc bromide technology

In response to some of the limitations of lithium ion and existing zinc bromide technologies, Australian-based company Gelion Technologies has developed a zinc bromide battery using gel instead of a liquid based electrolyte.

Essentially, the gel moves the electron charges faster.

Which means that a solar battery with this technology can charge in minutes.

Gelion also says it beats lithium ion in efficiency, lifespan, and cost.

However, this product isn’t yet available in the market.

But what’s exciting about this is that the technology can be incorporated into building materials.

In other words, your walls and your roof are batteries storing electricity.

Zinc and Bromide also have more supply and are cheaper materials than lithium and cobalt and would be able to scale easier.

Is this a perfect replacement for fossil fuels?

No, it’s not.

While producing electricity from sunlight IS renewable, the manufacture of batteries uses resources that are not renewable.

Namely, lithium, cobalt, zinc, and bromide.

Even salt is non-renewable (at least at the rate that humans consume it), but it is one of the world’s most abundant resources.

But while it’s not perfect, solar power with batteries does give us options.

It helps us be less reliant on public utility companies that may have frequent blackouts and brownouts.

And we can each make the choices we feel are best for ourselves and for the greater community.


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