It is a fact that solar panels and batteries go together, like peanut butter and jam. And while it’s possible to have just one of the two, doing so somehow doesn’t feel right. And yet, an increasing number of homeowners are considering ditching solar panels and going with just a home battery. But does that make any sense? Let’s find out.
Can You Install A Home Battery Without Solar Panels?
Yes, you can install battery storage at home without installing solar panels. In the more traditional, solar + battery setups, the battery is connected to both solar and your utility grid. When the solar power system is underperforming, the battery can take some energy from your utility company.
A standalone battery, on the other hand, is connected only to the grid, and charges entirely from it. While a solar-powered battery sounds like a more logical option, there are a few logical reasons to let the battery have a solo performance.
Reasons to Install a Home Battery Without Solar Panels
A common reason to have a battery without solar panels is an imperfect roof layout. Many homes have a roof that is far from ideal for solar panels. For instance, a south-facing, steep roof would generate disappointing levels of solar energy, and wouldn’t make solar panels a sound investment. Or a roof may have so much shading on it that once again, the meagre energy production levels wouldn’t justify the cost of solar.
Another reason relates more to wallets and less to roofs. Some buyers may simply be unable or unwilling to spend on both solar and battery - after all, the combo can carry a sizeable price tag. For instance, a Tesla Powerwall battery can cost up to $17,000 with installation. This is higher than the average cost of a typical, 5 kW solar power system, which costs around $13,500.
Naturally, one may be tempted to just go with the battery, especially if you are inclined more towards the battery's benefits than those of solar. Speaking of a battery’s benefits, let’s look at what a battery can offer homeowners without solar panels.
Benefits of Having a Home Battery Without Solar
A standalone battery can offer some of the key benefits of a solar + battery setup. Here’s a detailed discussion:
1. Fighting Power Outages
Installing a battery is an excellent way of fighting power outages. Modern home batteries come with enough energy storage capacity to power essential appliances in a home for hours, if not days.
Of course, in cases where blackouts last seriously long, a battery alone wouldn’t suffice (remember cyclone Gabrielle!). In such a case, having a solar power system would be perfect - you could keep charging the battery every day and use it through the blackout, even if it lasts several days.
However, for power outages that last a few minutes or a few hours, a standalone battery is more than sufficient. Let’s do a quick example. Suppose a home is hit with a 4-hour power cut and it has a 10 kWh battery installed. The wise homeowner decides to turn off the TV, patio lights, and all other appliances that aren’t essential. Let us say the operational devices are the following:
|Hours of use
|Total energy consumed
|3,500 Wh or 3.5 kWh
As we can see from a simple calculation, the home would need about 3.5 kWh in such a scenario. For a battery with a 10 kWh capacity, this is less than half of what it is capable of powering. If the usage remains constant, the same battery can power the home for a few more hours.
And if you expect a longer power cut, you can cut down on appliance usage even further, letting your battery save you from darkness for multiple days. Some buyers even decide to invest in two batteries instead of one, especially those who live in areas with longer power outages.
If you are installing a battery with the primary purpose of tackling power cuts, it helps to look at historical data for the frequency and length of the blackouts in your area, and choose a battery size based on that.
2. Lowering Energy Bills
At the onset, purchasing a battery to save money may sound counterintuitive - after all, it costs thousands of dollars. And yet, this is starting to become one of the reason’s important reason among families for choosing a standalone battery.
Most utility companies in New Zealand have variable power pricing. Hours of peak usage generally see higher power costs, while off-peak or night hours see lower pricing. Here is a part of the rate chart for electricity prices offered by Octopus Energy, a retailer. You can see that the difference between the highest price and the lowest price in a day is remarkable - peak usage prices are roughly twice the night-time prices.
Some home users run power-hungry appliances at night to save on energy bills. But for those who don’t want to do their laundry at 1 am, a battery can help shift a home’s energy consumption from the more expensive hours to the cheaper hours without actually changing the times of appliance usage. Modern batteries have enough smart functionality to allow you to set charging and discharging times through a simple tap on your smartphone.
You can charge the battery completely at night and discharge it during peak hours. Therefore, you could use your dishwasher right after dinner and not worry about the cost of running it. Let’s do some calculations to see how much two of New Zealand’s popular battery models can save you just by smartly managing your charging and discharging times.
Running the Numbers
For our calculation, we will use the Tesla Powerwall 2 (it’s a fan favorite, after all) and the Huawei Luna 2000 (check our detailed comparison of both models here). The Powerwall has a usable capacity of 13.5 kWh, while the Luna offers 10 kWh (with more sizes available). We are supposing that both batteries are located in Auckland and served by Octopus Energy. As seen in the table above, the peak hour rates for this location are $0.3058, while night rates are $0.1529.
Now, the owners of these batteries can save $0.3058 – $0.1529 = $0.1529 for every kWh of energy consumption they shift from peak hours to night hours.
As the Tesla Powerwall has a usable capacity of 13.5 kWh, its owner can shift 13.5 kWh from peak to night hours, saving 13.5 kWh x $0.1529 = $2.06/day.
Similarly, the owner of the Huawei Luna can shift 10 kWh of energy used from peak hours to night hours, saving 10 kWh * $0.1529 = $1.529/day.
But are these savings worth the investment? Let’s calculate the payback period for both batteries using the above numbers.
The Tesla Powerwall 2 costs $17,000 (for now, we will exclude the installation as the prices vary). Considering that it saves $2.06 every day, the battery will pay itself back in $17,000 ÷ $2.06 = 8252 days or 22.6 years.
The Huawei Luna, on the other hand, costs $10,500 and saves $1.529 every day, which means its payback period is around $10,500 ÷ $1.529 = 6867 days or 18.8 years.
Both the Powerwall and Luna come with a 10-year warranty. Ideally, the batteries should last anywhere between 10 and 15 years, which is still shorter than the calculated payback period. This means that the monetary savings alone from load shifting are not enough to justify the cost of batteries.
Some energy providers also offer 3 free hours of energy usage to promote the shift from peak hours to non-peak hours. For example, Contact customers in some areas can use free energy between 9 pm and midnight. While it might be optimistic to envision the Tesla Powerwall achieving a full charge during this cost-free timeframe, a closer examination of the battery's specifications reveals that it falls short of this expectation. When the Powerwall charges from the grid, it charges at a rate of 3.3kW. Therefore in 3 hours it would have only filled up with 9.9kWh of storage. Still that's a savings of $3.03/day, better than the examples above.
Summary: Should You Install a Home Battery Without Solar?
One thing is absolutely clear - if you have the roof and the budget for a system that includes both solar panels and a home battery, you should definitely install such a system. But if that is not possible, there are two things to consider.
Firstly, if you live in a location where power cuts are frequent, a battery can save you from the inconvenience and discomfort of living without power. That said, batteries alone barely pay themselves off, since they do not generate energy like solar panels do. And while they do save some money on energy bills by shifting the times of energy consumption, the resulting savings are not strong enough to make it the primary reason for installing a standalone battery.
To summarise, a standalone battery is excellent if fighting power outages is your primary goal. But for those who don’t have the budget for a solar + battery system, remember that you can add solar to an existing battery at a later date, just as you can add a battery to solar or another battery in the future. This not only gives you the ability to avoid a single, large expense but also allows you to figure out if you really need both solar and batteries for your home.
In conclusion, you should buy a standalone battery if you check these two boxes: your home has a terrible roof layout for solar, and you are subject to frequent blackouts.