Solar Battery Backup System For Home - Solar Backup Power

Updated on January 9, 2023

In recent years, many countries have been turning to alternative sources for electricity, such as solar and wind power. While these technologies are far more sustainable than fossil fuels , they are not without significant drawbacks.

For example, solar panels can only generate power when the sun is shining and wind turbines depend on fairly constant wind speeds over 5 metre per second. Solar backup power make complete sense.

For these reasons, lithium based solar battery storage represents a breakthrough in sustainable energy generation options, because it represents a means of storing the energy for later use.

What type of home solar storage batteries do I need?

The type of solar storage batteries recommended home are lithium-ion (Li) or lithium iron phosphate (LiFePo4). Lithium batteries have fast charge capability, medium cost, and high energy density. The storage capacity of lithium cells becomes more cost-effective the longer they are in use, supplying power when solar panels are dormant.

Solar panels provide power to a roof top photovoltaic system that is basically useless immediately after dark or during inclement weather.

A solar battery can store the energy generated by the panels during these times and feed it into the home when needed. Using a lithium-ion battery, this would result in uninterrupted electricity services for homes or businesses.

Video – Lithium Solar Energy Storage Batteries For Home Use

Do lithium batteries last longer?

Lithium batteries are inherently deep-cycle with a very high energy density, which allows them to store more energy for longer periods than some other battery types.

These batteries are also able to take a large amount of abuse without undue problems. Lithium-ion batteries can be recharged faster than other types of batteries due to their high charging-discharge capability.

This allows them to charge rapidly during the day and provide power at night or on cloudy days, when solar panels cannot produce as much power.

They include solar-powered lights and signs, flood lights, backup electrical supplies in case of storms or blackouts, and off-grid living.

Lithium Phosphate

Lead Acid

Number charge/discharge cycles

2000 (100% DOD)
5000 (80% DOD)

500 (80% DOD)


60% less than Pb

Deep cycle?

Inherently deep cycle

Special batteries

Cost comparision



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What’s Lithium?

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft, alkaline metal that can be found in many minerals like spodumene, petalite, and lepidolite.

Lithium has low reactivity with water and air. It makes up about 0.0005% of the Earth’s crust by weight, or one atom for every 100 particles of silicate rocks which are prevalent in the Earth’s continental crust as well as in some volcanic rocks such as peridotite and granite.

Although it occurs naturally in low concentrations, lithium has important industrial applications as a component of various ceramics, carbonates, and even in some rare minerals.

It is also widely used in the petrochemical industry as a component of lubricants and organic solvents.

Solar batteries for home – What lithium batteries are made of

There are various types of lithium batteries available in the market today, many well-suited to home battery use.

For example, lithium-ion batteries are one of the most popular types of rechargeable batteries used in many applications, such as cellphones and laptops. They are also used in cars and electric vehicles like those found in Formula E racing.

Another type is the lithium-polymer battery. These batteries have very high energy density, which means that they can store a higher amount of energy in a battery of given size than other types of batteries.

The first lithium-polymer batteries were developed in 2005, and this type of battery has been used for military purposes. They are generally portable and can endure more adverse environmental conditions than lead-acid, say.

Lithium phosphate batteries have many advantages such as long lifespans.

They can be charged and discharged up to 5000 times if discharge less than 80% of their capacity. They can also be discharged at a much faster rate than other types of batteries.

Solar batteries for home – What lithium batteries are made of

What is the best battery technology for home solar?

How Does Lithium Work with Solar Storage?

Lithium batteries are perfect for solar storage because they are light and very stable. They go well with solar panels because they can absorb high levels of energy for later use.

They can be installed easily, and users can choose from a variety of sizes and shapes to meet their individual needs. For example, smaller lithium batteries are often used for emergency lights in case of a power outage.

Why is lithium phosphate so important for the EV industry?

The electric vehicle industry is booming; in fact, studies estimate that it will reach $24 billion-worth of global sales by 2024.

The reason behind this sudden growth is attributed to advances in lithium battery technology. Electric cars are faster and have an extended range due to more efficient batteries.

They also do not emit harmful gasses into the atmosphere, so they are eco-friendly.

EVs have been gaining traction, and automakers are in a race to release more models. A battery loses its power after a while, and electric vehicles with such batteries would need to have them replaced every few years.

Do all electric cars use lithium batteries?

The Nissan Leaf has a 40 kWh battery that can only store enough energy for 150 miles. The battery is an EV’s weak point.

This means that the battery would eventually need to be changed every 5 years or so, and doing so would be expensive.

EV batteries need regular charging and so charging stations are needed. They are relatively expensive as well, as they require a significant amount of energy and materials to manufacture.

A good example of the capacity of lithium-ion batteries in an electric vehicle is the Chevy Bolt EV. You can get a Bolt with either a 40 kWh or 60 kWh battery pack.

This provides about 200 and 240 miles of range respectively on a full charge. The larger battery pack also has more power, which means it can go faster and farther when pulling heavy loads.



Type of EV

Battery Size (kWh)

Range (km)

Battery Type

Charge Time



All electric



Li-ion (NCA)

9h with 10kW charger


Leaf (S)

All electric



Li-ion (LMO)

11h 45min with 3.6kW charger



All electric



Li-ion (LMO/NMC)

4h with 11kW charger







1.5h with 3.5kW charger



All electric




7h with 3.5kW charger



All electric




10h with 7kW charger

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What are the global challenges that affect lithium production and what is being done to address them?

A major challenge for lithium production is the low supply and high demand. The extraction of lithium is a costly and time-consuming process, so manufacturers are not producing as much of it.

In addition, the demand is increasing due to the popularity of electric vehicles. The demand for lithium would probably exceed supply within the next 30 years.

Because of this, researchers and experts are working on other supplies of renewable energy that can be used in EVs.

They have also been working on improving battery technology so that it can be used with renewable energy without any problems. Researchers are also working on ways to extract lithium from recycling and waste materials instead of natural sources.

What is the best battery chemistry for a hybrid or electric vehicle (HEV or EV)?

What is the best battery chemistry for a hybrid or electric vehicle (HEV or EV)?

What is the best battery type for EVs?

Currently, lithium ion batteries are the best for EVs. They have the highest energy density that can carry a decent amount of charge without charge leakage. They also do not degrade as quickly as other battery types.

However, a different type of battery is needed if renewable energy is to be used in cars in order to reduce their carbon footprint.

There are many different technologies being tested by researchers and manufacturers, including solid-state batteries and graphene-based batteries that could be used with renewable energy.

Which is best, Lead Acid or Lithium Phosphate For Solar Home Battery Energy Storage?

Lead acid cells are still used for solar energy storage but they are not ideal. They are also highly toxic and pollute when discarded, although they can be re-cycled.

They do not cost as much as some other battery technologies but they can only withstand 500 charge cycles before needing replacement.

Lithium Phosphate cells are a newer technology that offer more power than lead acid cells but at a higher cost.

They also use less toxic materials and don’t degrade over time like lead acid cells do. They are safer and more environmentally-friendly than lead acid cells and they don’t require as much maintenance.

LiFePo4 batteries are a little larger than your average 12-volt battery, but they are lighter and more powerful. They are extremely safe and quite reliable as well. Their downside is their initial cost, but this is offset by a much longer life-cycle.

Lithium cells don’t have a memory effect and they can be recharged thousands of times. They are extremely safe, lightweight, and long-lasting.

Although Ni-MH recharges more quickly than NiCd batteries, Li-ion is more efficient with energy use and can produce a higher output for longer periods.

Worst and best batteries for solar home storage

I’ll list what are the best the worst and the most cost-effective battery options for solar or any other renewable energy storage system. I also want to introduce a brand new battery technology that is getting rave reviews and we are not talking about lithium ion batteries

What are the best batteries for solar?

Well, contrary to popular belief, the flooded lead-acid batteries that are used in cars are not the best option. In fact, they are one of the worst options.

Unfortunately, in the developing world mostly flooded lead-acid batteries are used because they are cheap and easily available. These car or truck batteries are designed for providing high bursts of current for a short duration of time, to run starting motor for the engine.

This is the inverse of the requirements of solar energy storage systems, which require the battery to provide relatively less current but for a longer duration of time.

The problem is not the lead acid chemistry but the design of the battery. A car cranking battery has smaller electrodes. For solar application deep cycle batteries are best suited. Deep cycle batteries have longer electrode plates inside them.

A lead acid battery is a very established technology and within the lead acid umbrella there are different types of battery names of which are as follows:

  • flooded lead-acid battery
  • AGM battery and
  • GEL battery

In flooded batteries the electrolyte is in liquid form and can flow, whereas in AGM and gel batteries the electrolyte cannot flow. These last two types batteries can be used in any orientation.

Both the AGM and the gel batteries are maintenance-free, whereas in flooded batteries the water for the electrolyte has to be topped up from time to time.

Again it is emphasized here that for solar application, avoid using car or even truck batteries. At the outset they might be cheaper, but in the long run they’ll turn out to be the more expensive option.

One should aim to acquire deep cycle batteries, be it flooded, AGM or gel batteries. In terms of price, the deep cycle flooded lead-acid batteries are the cheapest and they cost only about $70 to $80 per kilowatt hour.

The ATM and gel batteries are almost the same price but more expensive than flooded battery. Their price ranges from $260 per kilowatt hour to $330 per kilowatt hour.

Gel batteries are very similar to AGM in terms of performance but have a slightly higher lifespan.

What are the best batteries for solar?

IMO lithium iron phosphate batteries are best for home solar use

Next up we have lithium ion batteries. They are long-lasting, robust and durable. They’re also much lighter and smaller than lead acid batteries of equivalent capacity.

The prices for lithium ion batteries are dropping by almost 8 percent per year again within the lithium ion umbrella there are different types of batteries.

The two main types that are used in solar energy systems are lithium iron phosphate and lithium cobalt oxide.

The cheapest lithium ion option is the Tesla Powerwall, which comes out at $505 per kilowatt hour. Other lithium batteries, such as Simpliphi batteries, range between $900 to 1100 per kilowatt-hour capacity.

There are many Chinese brands which do provide lithium batteries at considerably lower prices but they are not renowned brands in the western world.

Lastly, we have the latest commercialized technology in the battery world and that is the saltwater battery, also called the sodium ion battery.

This battery is very exciting, not only because of its performance but also because of its price. It is one of the safest batteries on the planet. A saltwater battery can handle heat very well and is completely recyclable.

It is very stable battery, with no maintenance and it has high amount of charge cycles. Even if this battery is discharged deeply, it doesn’t make much of an impact on its health.

The price for this battery is around $400 to 500 per kilowatt hour, which makes it cheaper than lithium ion, but slightly more expensive than lead acid.

It should be understood that the saltwater battery has many more charge cycles at higher depth of discharge and therefore it is a more cost-effective option than lead acid.

Note that you can get over 5,000 charge cycles at 90% DoD. The saltwater battery has a couple of drawbacks:

  • Firstly, it is slightly heavier than a lead acid battery and
  • Secondly, it must be charged and discharged at lower rates than other batteries.

As noted earlier, the saltwater battery is a cheaper alternative to lithium ion and the prices are expected to drop further with developing competition and economy of scale.

To recap:

The best option in terms of longevity is lithium ion battery, if you can afford it. The next best option is the saltwater battery and lastly we have the deep cycle gel batteries.

How much power do I need off-grid?

How much power do I need off-grid?

How many batteries would you need to go off-grid?

The power required for off-grid living is a direct function of how much energy you use and your energy storage capacity. For an average home energy consumption of 29kWh/day you would need between 25 to 30 solar panels and 6 deep cycle batteries of 2400 watts (200Ah) each for 24 hours autonomy.

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The amount of power you need depends on your lifestyle. Generally speaking, it is best to have a 25% larger system than you think you will need so that it can accommodate future additions and upgrades.

Off-grid homes generally use solar panels, but can use wind turbines and generators. These are used in combination with batteries during bad weather conditions, night-time or when there is no sun shining.

By far the most common type of battery used in off-grid applications is lithium. These batteries are ideal because they are relatively light and compact.

You will need to install an inverter to convert the direct current from the solar panels and battery bank combination into alternating current for your home.

You will also need to install the correct size wiring so that your solar panels can be connected to your home. Circuit breakers, switches and other items such as net-metering will also be needed.

The table below shows lead acid power required to go off-grid for 24 hours with a home load of 28kWh/day:

Battery Backup For 24 Hours



Total load for 24 hours backup


Watt-hours (Wh)

Battery bank voltage



Battery amp-hour rating


amp-hours (Ah)

Required Batteries (60% DOD) Lead-Acid

583/0.6 = 972 (say 1000)


Number of batteries @250Ah each


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The above is for example only – lithium iron phosphate batteries are strongly recommended.

Renogy Lithium Batteries

How does a Powerwall work?

The Powerwall is a battery for your home which provides backup power and stores energy generated by solar panels.

The system is peak-shaving: it uses batteries to store energy when it’s cheap (at night) and then delivers it during times when electricity is expensive (typically during the day).

The Powerwall 2 has a capacity of 14 kWh (kilowatt-hours) which can be used in place of 1 to 3 kilowatts of wall electrical outlets. The price is $6, 000 before installation.

Powerwall specifications:

  • · Power: 2 kilowatts continuous, 3 kilowatts peak; battery capacity of 14 kWh (kilowatt-hours)
  • · Time: 10 hours to fully charge the battery from a low state of charge with 10 hours of sun and rolling to an 80% SoC with 20 hours of sun. Charging can be done at any time.
  • · Temperature: the battery will maintain its capacity below 15°C (unless otherwise specified, e.g. Powerwall 2), but will not be used below -20°C or above 45°C
  • · Size: 160 x 60 x 90 cm (approx 5-1/2 x 2-1/2 x 3-1/2 inches)
  • · Weight: 11 kg (23 pounds) for the Powerwall 2 and 13 kg (29 pounds) for the Powerwall 1.

How Much Lithium-Ion Battery Storage Exists in the U .S.?

To see an example of a lithium-ion battery in use in the U.S., look at the new electric bus fleet operated by Green City Ventures and Washington State Department of Transportation.

The electric buses were purchased from New Flyer Industries/NFI and are now serving as part of their commuter fleet.

These buses are equipped with lithium-ion batteries capable of supplying up to 15 kW (kilowatt) of electricity to the buses’ 400 V DC trolley system.

Each of the buses is equipped with two heavy duty lithium-ion batteries that are installed in the rear. These batteries are capable of providing up to approximately 2,000 miles or more in their life cycle.

The new trolley buses are also equipped with regenerative braking systems. This means that when the bus is slowing down, it captures energy through this system and puts it back into the lithium-ion battery for later use.

It can also be used to run various other components such as heating and air conditioning.

How Much Battery Storage is Available Globally?

There are approximately 2-5 million electric vehicles (EVs) worldwide! Because EVs utilize lithium-ion batteries to store their power, this means there will be a need for lithium production and distribution for these EV battery packs.

The lithium market is expected to grow from $23 billion in 2017 to $50 billion by 2025. Lithium is heavily mined in many areas of the globe including Australia, Chile, China, and Argentina.

The main reason that this market is expected to grow so rapidly is because of the increasing demand for lithium due to its use in batteries for EVs and other similar applications. The amount of lithium available worldwide for the battery market is already in short supply.

The price for lithium is expected to grow as well. There are only a few primary sources for obtaining lithium, and China has purchased many of these sources in recent years.


Lithium batteries have many advantages and potential disadvantages for home use. They are lightweight, very safe, durable, and they don’t lose their charge as quickly as other battery types.

There are also many different types of lithium batteries with different performance levels. Consider all of these aspects when deciding which type would be best for you.

A lot of research is devoted to improving the performance level of lithium batteries, which is a great thing!

With innovation in this field, the lithium batteries will be more efficient and less expensive. Lithium-ion battery technology has been used for many years in home electronics such as laptops and cell phones.

It has proven to be very reliable in that application, so you can rest assured that it will also be reliable for your home.

Related Questions:

How long will a 10kw battery last?

As a general rule, a 10kW lithium-based battery should only be discharge up to 80%. The average US home energy consumption is 1.2kW per hour, so a 10kW battery would last:

10 x 0.8/1.2 = 6.7 hours

The calculation depends on the time of day of the outage and reduced energy consumption is advisable.

What is the best battery for off grid?

Lithium phosphate is by far the best home energy storage solution for a domestic off-grid solar system. Lithium-based batteries are energy dense, are inherently deep-cycle and have a cycle life of 5000 times if discharged to 80% of capacity.

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