Can I Run My House On A Solar Battery?

The concept of running a house entirely on solar batteries involves installing a home solar battery system to store energy from solar panels and power your home. With solar panels generating electricity during the day and solar batteries providing power throughout the night, solar batteries can enable running a home fully on solar energy and going ‘off-grid’.

Interest and trends in using solar batteries for homes have grown rapidly in recent years. According to a study by the National Renewable Energy Laboratory (NREL), the U.S. market for residential solar-plus-storage grew over 300% from Q3 2017 to Q3 2019 ¹. Factors driving this growth include falling costs and advancements in battery technology, along with increased consumer interest in energy resilience and independence. Major solar installers like Tesla are offering solar battery options, further accelerating adoption.

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How Solar Batteries Work

Solar batteries, also known as energy storage systems, work by storing the excess energy generated from solar panels for use when the sun isn’t shining. The most common type of solar battery today is the lithium-ion battery (Palmetto, 2021). Lithium-ion batteries use a chemical reaction to store and release energy. When the solar panels generate more electricity than a home is using, the excess electricity gets stored in the battery. Then at night or on cloudy days when the solar panels aren’t generating electricity, the stored energy gets discharged from the battery to power the home.

The key components of a solar battery system include the battery itself, battery management system, inverter, and software/monitoring. The batteries are made up of individual battery cells encased in a protective housing. The battery management system monitors battery performance and protects against issues like overheating. An inverter converts the DC electricity stored in the battery into usable AC electricity for your home. Software allows you to monitor energy usage and battery performance (EnergySage, 2023). These components all work together to safely store and discharge solar energy in a home.

Consider Your Energy Usage

Analyzing your current home energy usage and patterns is an important first step when considering whether solar batteries can meet your household’s electricity needs. According to the U.S. Energy Information Administration, the average U.S. household consumes about 10,500 kilowatt-hours (kWh) of electricity per year (EIA). However, electricity use varies widely depending on factors like home size, number of occupants, appliances, electronics usage, and climate.

Take a close look at your monthly electric bills over the past year to understand your home’s energy usage patterns. Pay attention to seasonal fluctuations and times of peak demand. Also make note of when you use the most electricity during the day. Understanding your household’s energy profile will help properly size a solar battery system to meet your needs.

Improving your home’s energy efficiency is also key. Simple upgrades like LED lighting, programmable thermostats, and insulation can help reduce energy waste and lower electricity demand. The less power your home requires, the smaller and more affordable a solar battery system can be to fully meet your needs.

Calculate Your Solar Battery Needs

The size of the solar battery bank you need depends on several factors:

Daily energy usage – The total amount of energy your household uses per day, measured in kilowatt-hours (kWh). This includes electricity for lights, appliances, electronics, AC, etc. Audit your energy bills to determine your daily usage.

Days of autonomy – The number of days the battery bank must supply power without sunlight. 3-5 days is typical for off-grid systems.

Depth of discharge – The depth to which you can drain the batteries before recharging. 50% is optimal for longevity.

To calculate the minimum battery capacity needed:

Battery bank size (kWh) = Daily energy use (kWh) x Days of autonomy / Depth of discharge

For example, if your daily energy use is 5 kWh, you want 3 days of autonomy, and a 50% depth of discharge:

Battery bank size = 5 kWh x 3 days / 0.5 = 30 kWh
(Source: https://www.solacity.com/how-to-size-a-solar-system-that-really-works/)

Allow for some extra capacity as a safety factor. Also consider solar input and future energy needs when sizing your system.

Solar Battery Options

When selecting a solar battery, you need to consider the different battery types available and weigh the pros and cons of each for your particular situation. There are a few main types of solar batteries:

Lead-Acid Batteries

Lead-acid batteries are the most mature and widely used battery for solar energy storage. They use lead electrodes and sulfuric acid electrolytes. Two common types are flooded lead-acid batteries and sealed lead-acid batteries like AGM and gel cell batteries [1].

Pros:

Inexpensive initial cost

Proven and reliable technology

Cons:

Shorter lifespan of 5-10 years

Heavier weight
Potential maintenance requirements

Lithium-ion Batteries

Lithium-ion batteries use lithium metal oxide cathodes and graphite anodes. Types include lithium cobalt oxide, lithium manganese oxide, and lithium iron phosphate batteries. They have high energy density and efficiency [2].

Pros:

Long lifespan of 10-15 years
Lightweight and compact

High efficiency

Cons:

Higher upfront costs

Degrades faster in hot climates

When selecting a solar battery, you’ll need to weigh factors like upfront cost, longevity, maintenance needs, efficiency, weight, size, and performance in your climate.

Installation and Setup

Installing a solar battery system involves several key steps. First, the solar panels and racking need to be mounted, usually on the roof. The panels are wired together into an array. Next, the inverter and battery storage unit are mounted, typically on an exterior wall or in the garage. The inverter converts the DC electricity from the panels into usable AC power. The battery stores energy for use when the panels aren’t producing, like at night.

Running conduit and wiring between the solar array, inverter, battery and main electrical panel is a key part of the installation process. Proper wiring sizes must be used to handle the solar system’s output. All electrical connections need to be made according to local codes and permitted. Most areas require a licensed solar contractor to obtain permits and complete the installation.

Professional installation is highly recommended, as solar battery systems involve complicated electrical work. Trying to DIY an installation often leads to improperly wired connections, which can be dangerous. Hiring a reputable local solar company ensures proper permitting, installation, and activation of the system. They will also handle any inspections required by the local permitting office.

Overall, installing a solar battery system requires expertise in solar electrical systems, as well as knowledge of local building codes. Leaving the installation to professional solar contractors reduces risks and ensures your new solar battery system is safely and properly connected.

Operating and Maintenance

Keeping your solar battery system running well requires some regular maintenance and care. Proper solar battery maintenance can extend the life of your batteries and maintain optimal performance.

You should routinely inspect your batteries, cables and connections for any damage or corrosion. Clean any dirt or dust buildup on the batteries with a cloth dampened with distilled water and baking soda, as recommended by experts (Proesolar, Energysage). Avoid submerging the batteries in water. Allow batteries to fully dry before reconnecting.

Check that cables are firmly connected and free of oxidation. Loose connections can cause power loss and damage. Replace any damaged cables and connectors. Periodically use dielectric grease on connections to prevent corrosion (Unbound Solar).

Recharge batteries fully at least once per month to prevent sulfation buildup, which degrades batteries over time. Follow the charging recommendations from your manufacturer. Most lithium-ion batteries charge best in constant voltage mode (Unbound Solar).

Monitor your solar battery management system data regularly. Look for any error codes or alerts indicating issues. Proactively replace components like inverters and charge controllers before they fail to avoid downtime.

Over years of use, solar batteries will degrade and need replacement. Lithium-ion batteries can last 5-15 years under proper care (Energysage). When capacity drops below 80%, it’s time to replace batteries. Reuse or recycle old batteries properly.

Costs and Incentives

The upfront cost of installing a solar battery system can range from $5,000 to $20,000 depending on the size of your home’s energy needs and the battery capacity. Bigger battery capacity means higher upfront costs but also greater energy storage and potential cost savings over time. The return on investment for a solar battery system is usually 5-10 years.

There are federal and state incentives available that can help offset the initial costs of installing solar batteries:

The federal solar Investment Tax Credit (ITC) offers a 26% tax credit for systems installed in 2023. This applies to both solar panels and battery storage systems. The ITC will drop to 22% in 2024 before expiring completely for residential projects in 2025 (Do Batteries Qualify for the Solar Tax Credit in the Inflation Reduction Act?).

Some states like California offer additional rebates on top of the federal ITC through programs like the Self-Generation Incentive Program (SGIP), which provides incentives of up to $850/kWh of battery capacity (Solar Battery Incentives and Rebates).
Your local utility company may also offer rebates or other incentives for installing solar batteries as part of their renewable energy programs.

Consult a tax professional to determine exactly how much you can save on a solar battery system through federal and state incentives. The savings can be substantial and make these systems more affordable.

Limitations and Considerations

While solar batteries can provide clean energy for your home and help reduce your electric bill, there are some limitations and considerations to keep in mind:

Grid dependence: Most home solar battery setups are still connected to the electric grid to serve as a backup source of power. This means you may still rely on your utility provider during extended periods of cloudy weather when your solar panels aren’t generating enough energy to fully charge the batteries.

Backup power capacity: The solar battery capacity in a typical home setup is usually only enough to power critical loads during an outage, not your whole home. So you may need a backup generator if you want full backup capability. According to Forbes, most home batteries provide 5-8 hours of backup power.

Weather impacts: Solar panels rely on sunshine to charge batteries. Cloudy weather, storms, or winter seasons can limit the amount of solar energy available on any given day, which reduces how much your batteries can charge. This may increase your dependence on grid power.

Maintenance and replacements: Solar batteries have a limited lifespan and will need to be replaced every 5-15 years depending on the model. They also require some periodic maintenance which adds to long term costs.

Upfront costs: Adding solar batteries to your home solar system significantly increases upfront costs. Tax credits and incentives can offset some of the investment, but it’s a higher upfront price than solar alone.

Conclusion

Running a house completely on solar batteries is technically viable but involves careful planning and significant upfront investment. The feasibility depends largely on your home’s energy usage and needs, as well as the solar resources available in your area. With a properly sized solar battery system, thoughtful energy efficiency improvements, and routine maintenance, it is possible for many households to meet the majority or entirety of their electrical needs through stored solar energy. However, solar batteries currently have limitations in storage capacity and lifespan. They may not fully eliminate your need for grid power. Consider costs, incentives, your lifestyle needs, and grid dependence when weighing solar batteries. With mindful system sizing and energy management, they can provide clean, renewable energy and potential utility bill savings. Discuss options with solar professionals to determine if battery storage is right for your home.