How Does Solar Storage Work?

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How Does Solar Storage Work

As extreme weather becomes more and more common, so are power outages. Unfortunately, intense storms and high winds can cause blackouts, often from downed trees.

In Oregon and Washington, many power outages are caused by winter snow or ice storms or from emergency power safety shutoffs. In these cases, your electric utility company intentionally causes a power outage to help prevent wildfires. Unfortunately, the power can be off for an extended period as utility companies wait for conditions to improve.

Thankfully, solar panels with battery storage are an excellent way to have backup power during a grid outage. That means that the batteries will power your home, but the system can continue to charge the batteries from the sun during the day. Solar plus energy storage has become much more popular for Smart Solar Energy customers in recent years. Let’s explore how these systems work, the cost of solar batteries, and if they are worth the additional cost.

Why have solar batteries become more common recently?

In recent years, advanced lithium-ion batteries have become available for the residential market and the cost has decreased. Just a few years ago, the primary option was lead-acid batteries, which have many drawbacks. This advancement made energy storage far more appealing to homeowners. In fact, some people with existing solar panels have even added solar storage capabilities afterward.

Also, some states or utility territories don’t have net metering programs, but this is not the case in Oregon and Washington. Thankfully, Portland General Electric, Pacific Power, the Eugene Water & Electric Board, PSE, and other Pacific Northwest based power companies do offer net metering. This means that you will get credit on your electricity bill for the surplus solar power you feed to the grid. In areas without net metering, like Hawaii, battery storage has become more popular as a result.

What does a solar system with batteries contain?

Your solar power system will include the following essential components:

Solar Panels

Your solar system will have solar panels that use sunlight to create a current of solar electricity. Suppose you live in an area with net metering, such as Portland, Salem, or Olympia. In that case, you can either receive credits for surplus solar electricity on your utility bill, or you can charge your batteries from the solar PV panels.

Solar Panel

Battery Charge Controller

The charge controller, also known as the charge regulator, helps prevent the batteries from overcharging by regulating the voltage and current coming from the solar panels.

Solar Inverter

The solar panels produce direct current (DC) electricity, whereas your home uses AC (alternate current).  Your inverter converts the electricity from DC power to AC currently for use by the appliances and gadgets in your home.

Solar Storage Batteries

There are numerous different kinds of solar storage batteries on the market. The needed capacity of the battery depends on its use. Batteries around 3 to 14 kWh are popular for use in single-family homes with moderate home energy consumption.

Often, more than one battery from the same manufacturer can be combined to increase the stored energy capacity of the home. For example, you could install an Enphase Encharge 3 and an Encharge 10 in your home to have 13.44 kWh of combined capacity.

Will my solar batteries automatically kick in during a blackout?

Yes, during a power outage, your batteries will automatically start supplying the critical loads in your home with power. In fact, our customers have told us that they realized there was a power outage because all the other homes in the neighborhood were all dark. Your system will require less than a second to deliver electricity, so you may not even know when there is a blackout right away.

By contrast, a generator takes about 10 to 20 seconds to power up. Although this is relatively quick as well, it is long enough to need to reset all the clocks. Also, generators rely on fossil fuels to operate, and they are noisy. After extreme weather events, it might be difficult to buy fuel for a generator.

What PV batteries does Smart Solar Energy install?

At Smart Solar Energy, we primarily install the Enphase Encharge 3 and Encharge 10, but occasionally use the Tesla Powerwall 2 and LG Chem RESU battery. These options are advanced lithium-ion batteries with excellent reputations and long warranties. None of these storage options require ongoing maintenance and are ideal for residential applications. In addition, they are all wall-mounted energy storage solutions and have a sleek appearance.

Enphase Encharge 3

Enphase 3

The name Enphase is nearly synonymous with high-quality solar microinverters. Instead of a solar energy system having one centralized inverter, microinverters are mounted on each panel to convert the electric output from DC to AC current for use throughout the home. What we like about Encharge 3, 10, and 13 is that it’s an all-in-one solution with integrated microinverters. Also, multiple batteries can be combined, delivering just the right amount of backup power.

The Enphase Ensemble 3 is an excellent option for homes that need a relatively modest amount of backup power and a more economical solution. It has a usable capacity of 3.36 kWh and includes a 10-year warranty or 4,000 cycles and at least 70% of its capacity at the end of the warranty period.

Enphase Encharge 10

Enphase 10

Compared to the Ensemble 3, the Ensemble 10 is a larger capacity battery with a total capacity of 10.5 kWh and a usable capacity of 10.08. However, they offer the same warranty of 10 years or 4,000 cycles and at least 70% of its capacity.

Enphase Encharge 13

10kw battery

Not surprisingly, the capacity of the Encharge 13 is even bigger than the Encharge 10 and has a usable capacity of 13.4 kWh and a similar warranty.

Tesla Powerwall 2

Known for its sleek cars, the Tesla name is associated with clean energy and advanced products. The Powerwall 2 has a usable capacity of 13.5 kWh. The price of the Powerwall 2 is a bit higher than the other battery options but so is the capacity. Tesla has announced the Powerwall 3 battery, but the exact release date is still unknown.

The Powerwall 2 solar storage battery includes a ten-year warranty. The warranty ensures that the battery retains 70% of its ability to hold a charge during the warranty period. The Powerwall also has a throughput warranty which relates to how much power the battery is expected to deliver throughout its lifespan. The Powerwall 2 has a throughout warranty of 37 MWh.

LG Chem

LG Chem Solar Battery

LG is a Korean company known for high-quality electronics and has had an excellent reputation for decades. And, it is one of the largest lithium-ion manufacturers globally. The LG Chem RESU 10h battery has a usable capacity of 9.3 kWh.

LG Chem also offers a ten-year warranty for its RESU batteries and ensures they will retain at least 60% of their original capacity to hold a charge. Also, LG Chem includes a throughput warranty of 22.4 MWh.

Which is better, the Powerwall 2, the LG Chem RESU, or the Enphase Encharge 13?

There are advantages and disadvantages to all three options, so there is not a clear winner. The Smart Solar Energy team really likes how the Encharge batteries are an integrated clean energy solution with excellent capabilities, so we tend to install more of these home solar batteries.

The Powerwall 2, RESU, and Encharge 13 have really similar power outputs of around 5 kW of electricity continuously and can provide about 7 kW of peak power. This means that the batteries can deliver 7 kW of electricity for a short period of time and sustain an output of 5 kW. According to these measures, the Encharge 13 performs a bit better than the others, delivering 7.6 kW of peak power.

One advantage of the RESU battery is that it’s 94.5% efficient, compared to the Powerwall 2, which is 90% efficient, and the Encharge at 89%.

For homes that need more power, sometimes multiple batteries are used. When installing the Powerwall 2, nine batteries can be combined. By contrast, only two LG Chem batteries can be combined. Encharge batteries also allow multiple units to be wired together, depending on the configuration.

 

Encharge 3

Encharge 10

Encharge 13

RESU 10

Powerwall 2

Capacity

3.5 kWh

10.5 kWh

13.9 kWh

9.8 kWh

14 kWh

Usable Capacity

3.4 kWh

10.1 kWh

13.4 kWh

9.3 kWh

13.5 kWh

Roundtrip Efficiency

89%

89%

89%

94.5%

90%

Peak Power

1.9 kW

5.7 kW

7.6 kW

7 kW

7 kW

Continuous Power

1.3 kW

3.8 kW

5.1 kW

5 kW

5 kW

Warranty Period

10 years

10 years

10 years

10 years

10 years

Will my outlets have power during an outage if I have solar batteries?

The Smart Solar Energy team installs what is called a critical load panel that ensures that your most important loads have electricity. That means that your critical loads will have power during an outage, but not all devices will run unless they are wired accordingly. We use licensed electricians with extensive solar energy knowledge to complete the installation.

For example, you might have your refrigerator, freezer, and wi-fi router on a critical load panel but not the washer, dryer, and air conditioner. The Smart Solar Energy team customizes all its installations and works with homeowners to determine which loads need power during a grid outage.

Should I use lead-acid batteries instead of lithium-ion ones?

Years ago, lead-acid batteries, similar to the ones in our cars, were commonly used with both off-grid and grid-tied solar systems to store electricity. However, these batteries have many drawbacks, making them a good fit for only a small percentage of solar installations. Now, lithium-ion batteries, such as the Tesla Powerwall, have many advantages compared to lead-acid batteries.

Unfortunately, lead-acid batteries are not very durable and don’t typically last very long because they have a limited cycle life. In fact, they are usually only suitable for 500 to 1,000 cycles, whereas the Enphase Encharge 3 & 10 are warrantied for 4,000 cycles.

Also, these batteries are not efficient, leading to wasted energy, and they are not space-efficient. Flooded lead-acid batteries release noxious acidic gas and need to be in a sealed box that is vented to the outside. In addition, they need to be topped off with distilled water, and some homeowners forget to do this, which can decrease durability. However, sealed AGM batteries do not need to be topped off or placed in a sealed box, making them more convenient for home use. One advantage to lead-acid batteries is that they have a lower upfront cost.

By contrast, the advanced solar batteries that are popular today do not require maintenance, are highly reliable, and efficiently store energy for many years. In fact, many solar battery manufacturers offer warranties for about ten years but the batteries can last longer.

Will I have power during daylight hours if I have solar panels without batteries?

During a grid outage, your home will not have backup power unless your solar power system has storage capacity. This is to make sure the power lines are safe for workers to make repairs. If your solar system has battery storage, you will have power for essential loads.

How much do solar batteries cost?

Although advanced solar batteries have decreased in cost, they are still a big investment and add considerably to the total cost of the solar PV system. Also, electricians need to wire an additional subpanel which increases the expense.

Typically, solar batteries can add about $12,000 to $16,000 to the total system cost for a battery powerful enough for a household (and not just a couple of gadgets). The good news is that the federal tax credit includes solar storage batteries and labor, so you can earn a larger solar tax credit if you add PV battery storage. The state also offers the Oregon Sore + Storage Rebate Program, which can also lower the total system cost. Unfortunately, this can be a lengthy process to receive approval for battery rebates.

Family with candles

Are solar batteries worth the additional cost?

If you are installing solar panels, you may be debating whether or not to install solar batteries. Some of this depends on your situation and how important it is to have backup power. For example, if you lose power frequently, it will be more worthwhile than if you live in an area with very reliable power. Also, how critical is it to have power 24/7?

Some areas, particularly in remote parts of Oregon may experience more lengthy power outages. These can be particularly disruptive compared to shorter outages.

If you work from home, you may lose some productivity due to power outages. Likewise, some homeowners may need to power critical medical equipment. Some Oregon homeowners are very concerned about frozen pipes during a snow or ice storm, and solar batteries could prevent this problem (depending on the heating equipment).

Paying a bill

Also, both Portland General Electric and Pugent Sound Energy offer time-of-use rates to utility customers. This means Oregonians and Washingtonians can opt-in to this rate plan. With time-of-use rates, the cost of electricity varies by the time of day. For example, power is cheapest in the middle of the night, when demand is low. Then, electricity rates increase in the late afternoon.

With time-of-use rates, homes with solar batteries can save more money because these homes can use stored power when the rates are highest and pull from the grid when needed when rates are lowest. Having stored power gives the homeowners greater flexibility on when they must rely on stored power, resulting in lower power bills.

Another consideration is the federal solar tax credit is still in effect at 26% of the total system cost. Unfortunately, it will taper down to 22% in 2023 before it expires completely for residential systems (unless extended by Congress). Therefore, 2022 is an attractive year to install solar batteries because the incentive will be at a lower percent next year.

Regardless of whether or not you decide to install a PV battery with your solar panels, we want you to make the best decision for your household. At Smart Solar Energy, we provide useful information for solar shoppers to make the best decision for their budget, goals, and property.

Want to learn more about installing a solar battery on your home?

Contact the Smart Solar Energy team today!

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