Do I need a battery for my solar system?

Three Growatt Batteries

Batteries for a solar system are gaining popularity due to various factors, as we’ll elaborate on here. Once considered a novelty, solar storage is now a practical option for numerous homeowners, not limited to those seeking to go completely “off-grid”. Technological advancements and attractive government incentives and tariffs have played significant roles in making this possible.

This article aims to educate you about solar batteries, enabling you to determine whether they are the right fit for your property and needs. Within this blog post, you will discover responses to the following topics:

What are energy storage or solar batteries?

Solar batteries work similarly to regular batteries found in TV remotes, but on a larger scale. Instead of storing energy for a remote, they harness photovoltaic (PV) energy from the sun through a solar panel system. Owning a solar battery ensures you never run out of power, and with solar panels, you can even go off-grid, relying solely on your solar setup’s stored energy to power your property.

Additionally, as explained below, you can sell the energy stored in the solar battery back to the grid, potentially earning money through government initiatives and tariffs. Unlike regular batteries that deplete, solar batteries continuously recharge from solar power—excluding nighttime—making them a reliable source of energy.

How do they work?

There are several different types of solar batteries available on the market. Some of the most common types include:

  • Lead Acid Batteries: Lead-acid batteries are widely used and come in two variations: flooded and sealed. Though cost-effective, they have shorter lifespans and lower energy density compared to other types.
  • Lithium-Ion Batteries: Lithium-ion batteries are popular for their high energy density, longer lifespan, and lightweight design, making them a common choice for solar energy storage.
  • Saltwater Batteries: These eco-friendly batteries use saline electrolytes, offering non-toxicity and extended lifespans. However, they currently have lower energy densities compared to lithium-ion batteries.
  • Flow Batteries: Flow batteries store energy in liquid electrolytes, providing scalable capacity and potentially longer lifespans due to the replaceable electrolyte.
  • Nickel-Cadmium (Ni-Cd) Batteries: Though robust and reliable, Ni-Cd batteries are less common due to environmental concerns regarding cadmium, with lower energy density.
  • Nickel-Iron (Ni-Fe) Batteries: Ni-Fe batteries have a long lifespan and are ideal for off-grid applications, but they have lower energy efficiency and higher maintenance requirements.
  • Sodium-Ion Batteries: A new development aiming to rival lithium-ion batteries, sodium-ion batteries use sodium ions and promise low-cost and abundant materials. When selecting a solar battery, consider capacity, depth of discharge, cycle life, efficiency, and cost to meet your specific needs and budget. When choosing a battery for a solar system, it’s essential to consider factors such as capacity, depth of discharge, cycle life, efficiency, and cost to find the best fit for your specific needs and budget.
Batteries for a Solar System - Residential

Are solar batteries expensive?

The cost of solar batteries can differ based on individual needs. Primarily, it is influenced by the size of your solar system, which determines the necessary storage capacity and, subsequently, the cost of the batteries.

Just like any product, different brands and models come with varying features. When choosing a battery durability and capacity are important factors, so aligning these with your budget is the best approach.

How much energy do they store?

The storage capacity of a solar system’s battery and the required amount of storage necessitate distinct considerations. To make informed decisions, households must account for both the solar system’s size and their peak energy usage. For example, a 5kW solar power system can generate approximately 20kWh of energy on sunny days, resulting in an annual production of around 4,500 kWh. Without batteries, a system of this size would send about 13kWh daily to the grid. For optimal storage of excess energy, a battery capacity between 10 and 13kW is ideal.

What is the lifespan of a battery for a solar system?

Solar batteries available in the market today can operate for up to 15 years, and as technology progresses, their lifespan is expected to grow further. Although a 15-year duration is significant and corresponds to the time it takes for a solar setup to become cost-effective, it’s crucial to recognize that the battery may require replacement before the solar panels.

To provide additional reassurance, major manufacturers offer warranties for their products, with the most common warranties lasting for ten years or 10,000 charge cycles (whichever comes first).

Which factors affect the life of an energy storage battery?

The lifespan of a solar battery is influenced by several factors, including its usage frequency, battery type, and storage environment. Here’s a more detailed explanation:

  1. How often the battery is used: Similar to phone batteries, regular charging and usage impact the effectiveness of a solar battery over time. If the solar battery is consistently used to power a property, it will wear out faster than one used only for emergencies or occasional purposes. Living off-grid and subjecting the battery to repeated charge cycles can also accelerate its wear and tear.
  2. The type of battery you install: There are three main types of solar batteries: lead-acid, lithium-ion, and saltwater batteries. Among them, lithium-ion batteries offer the longest lifespan and the highest storage capacity. Refer to the section above for a more detailed comparison of the three types.
  3. The environment where the battery is stored: The storage location of the solar battery plays a crucial role in its longevity. Ideally, the area should be dry and temperature-controlled, avoiding extremes of heat or cold. Each battery type has specific storage temperature recommendations.
    For example:

– Lead-acid: 4°C to 8°C
– Lithium-ion: -17°C to as high as 60°C

Temperature change

To preserve the battery’s performance, store it in a designated, temperature-controlled environment, and avoid direct sunlight. Low-maintenance batteries can be stored indoors, while others may require specific conditions like a locked, well-ventilated box in a shed, garage, or outhouse.

For all battery types, storing them in an area with adequate thermal mass, such as concrete or stone, helps absorb excess heat energy, safeguarding the battery’s condition and performance. For questions about solar batteries or panels, consult a dedicated solar battery expert, who can offer tailored insights and guidance.

By considering and optimising these factors, you can extend the life of your energy storage battery and maximise its performance over time.

What government incentives are available for solar batteries?

The government has reduced the VAT to zero on new solar power and battery systems. There is also a scheme called the Green Deal that will benefit some households.

How do I choose a battery for a solar system?

To choose a solar battery, you should consider factors such as your energy consumption, required storage capacity, battery type (e.g., lithium-ion for longer lifespan), and ultimately your budget. It is also important to evaluate the battery’s depth of discharge and warranty coverage. Assess the storage environment, ensuring it’s temperature-controlled and dry. Lastly seek guidance from a solar expert, like SolarGain, to find the best fit for your needs and preferences.

Contact us at 0800 001 6258 or complete our form for a Free, no-obligation Survey and find out how solar batteries might work for your new solar system.

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