Lead-acid Batteries<\/strong><\/h4>\n\n\n\nThese can also be divided into two basic types: sealed or flooded.<\/p>\n\n\n\n
A flooded lead-acid battery has a lifespan of between five and seven years, and requires more maintenance*, while the sealed type only lasts between three and five years. Sealed lead-acid batteries aren't fully enclosed, as they have vents in the sides to allow gasses to escape.<\/p>\n\n\n\n
Lead-acid batteries are the cheapest option in the short term but will need to be replaced much earlier than lithium batteries.<\/p>\n\n\n\n
*also known as 'wet' lead acid batteries, they have removable caps and need to be topped up with distilled water.<\/em><\/p>\n\n\n\n<\/p>\n\n\n
\n
<\/figure><\/div>\n\n\n<\/div>\n\n\n\n
Lithium-ion Batteries<\/strong><\/h4>\n\n\n\nThese are a much more attractive option - literally. They are compact, with most examples being half the size of a typical lead acid battery, and they are designed to look good.<\/p>\n\n\n\n
They also have a far superior lifespan, with an average of around ten years! While they are undoubtedly more expensive, they are highly efficient and last much longer.<\/p>\n\n\n\n
Considering that modern solar panels can last between twenty-five and forty years, you might be expected to replace a lithium-ion battery only two or three times during this time. With a lead acid battery, you might get through six or seven in the same amount of time!<\/p>\n\n\n\n
<\/p>\n\n\n
\n
<\/figure><\/div>\n\n\n<\/div>\n\n\n\n
What Does 'Battery Size' Mean?<\/strong><\/h2>\n\n\n\nThis refers to battery capacity<\/em> rather than the item's physical size.<\/p>\n\n\n\nA battery's capacity is the maximum amount of energy that it can hold at any one time, and this is measured in kilowatt-hours (kWh).<\/p>\n\n\n\n
However, the most important figure to note is the usable <\/em>capacity, also known as the depth of discharge<\/em> limit (or DoD). In plain English, this means the actual amount of power you can use without damaging the battery. You will rarely be able to use the full capacity of any solar battery!<\/strong><\/p>\n\n\n\nFor example, take a 6.5 kW battery with a depth of discharge limit of 94.5%. You can only use 6.14 kW of the energy stored in the battery before it needs charging again. If you exceed this, you will affect the battery cycle (the number of times it can be charged and discharged) which will shorten its lifespan.<\/p>\n\n\n\n
It is essential to know this, as all solar battery systems have a different maximum depth of discharge limit. If you regularly discharge the battery (use up all the stored energy) beyond this depth of discharge limit, you will drastically reduce its lifespan and potentially cause irreversible damage.<\/p>\n\n\n\n
A lead acid battery will probably have a much lower DoD, usually around 40-50%, while lithium-ion batteries are generally between 80-95%. You might even find some very new lithium-ion batteries that boast 100% usable capacity, but these are fairly rare.<\/p>\n\n\n\n
So, when you choose a solar battery be sure to check the usable capacity (or DoD) against the nominal capacity. Generally speaking, the higher the DoD, the better, as you get to use more of the power without the battery needing to be charged.<\/p>\n\n\n\n
<\/div>\n\n\n\n
How Much Does Solar Battery Storage Cost?<\/strong><\/h2>\n\n\n\nA lead-acid battery generally costs between \u00a32,500 and \u00a34,500 depending on its usable capacity in kilowatt-hours.<\/p>\n\n\n\n
Lithium batteries are typically between \u00a33,500 and \u00a36,000 due to their superior lifespan and discharge rate.<\/p>\n\n\n\n
While it might be tempting to go for the cheaper option, remember that you'll potentially be replacing the lead battery several times. It's definitely worth considering the lithium-ion variety if you can afford the initial investment, not only for its lifespan but also because of the improved performance and high efficiency.<\/p>\n\n\n\n
<\/div>\n\n\n\n
Solar Battery Sizes: Which One Do I Need?<\/strong><\/h2>\n\n\n\nThere are several different sizes, ranging from 1kWh up to around 25kWh, so you'll need to choose carefully.<\/p>\n\n\n\n
This involves a bit of work as you'll need to gather some information and calculate the ideal size. Here's a list of things you'll need to know:<\/p>\n\n\n\n
<\/div>\n\n\n\n
The Size of Your Solar Panel System<\/strong><\/h4>\n\n\n\nAgain, we're not talking about the physical dimensions here (although that plays a role, as the amount of available roof space may limit the number of panels you can install). Instead, this refers to the total wattage output of the solar panels.<\/p>\n\n\n\n
<\/div>\n\n\n\n
Your Energy Consumption Each Day<\/strong><\/h4>\n\n\n\nThis is pretty easy to do if you have a smart meter, otherwise, you can find the information on your energy bills.<\/p>\n\n\n\n
<\/div>\n\n\n\n
How Much Energy You Use During The Night<\/strong><\/h4>\n\n\n\nAgain, a smart meter or electricity bill will tell you this. Ideally, we would need to be able to get figures relating to daily and hourly energy usage to calculate accurately.<\/p>\n\n\n\n
<\/div>\n\n\n\n
The Amount Of Energy Your Solar Panels Generate<\/strong><\/h4>\n\n\n\nFor those with an existing solar PV system, you can check the display on the inverter. Some systems come with an app that monitors the output. If your solar panels haven't been fitted yet, then your installer or the manufacturer can tell you how much electricity you can expect them to produce.<\/p>\n\n\n\n
<\/p>\n\n\n
\n
<\/figure><\/div>\n\n\n<\/div>\n\n\n\n
Are You Planning To Go Off-Grid?<\/strong><\/h4>\n\n\n\nIf you want to get cheaper electricity, then a single battery will probably do (depending on electricity usage), but for off-grid use, you'll need several to ensure that you don't lose power during a heavy winter.<\/p>\n\n\n\n
The size of your property also plays a role, so here's a rough guide as to what energy storage capacity you might need according to the building size:<\/p>\n\n\n\n
<\/div>\n\n\n\n
Four Bedroom - 10kWh<\/strong><\/h4>\n\n\n\n<\/div>\n\n\n\n
Three Bedroom - 8kWh<\/strong><\/h4>\n\n\n\n<\/div>\n\n\n\n
Two Bedroom - 4kWh<\/strong><\/h4>\n\n\n\n<\/div>\n\n\n\n
One Bedroom - 2kWh<\/strong><\/h4>\n\n\n\nUsing this information, you can find a lower and upper limit, a minimum and maximum amount of solar power storage you might need. You would then go for a battery system somewhere in the middle - in most cases, it will match the above list relating to property size, but it all depends on the output of your solar panels and the size of your solar array.<\/p>\n\n\n\n
Although it can seem a complex process, it all makes sense in the end. And if you are still uncertain, Skylamp Solar will do all the calculations for you to ensure that you get the right solar battery storage for your home or business.<\/p>\n\n\n\n
<\/div>\n\n\n\n
Why Is Battery Size Important?<\/strong><\/h2>\n\n\n\nYou need a battery storage system that suits the size of your solar array. If you buy one that's too small, you'll have to rely on an energy provider when you run out of stored electricity.<\/p>\n\n\n\n
And if you choose one that's too big, your solar panels won't be able to charge them fully. Why is this a problem? Because if the battery never reaches full charge it often leads to chronic undercharging <\/em>that will affect performance and lifespan.<\/p>\n\n\n\nGiven that you've probably paid somewhere between \u00a31,600 and \u00a36,000 for your solar battery, that's not very welcome news! The lesson here is that bigger is not always better.<\/p>\n\n\n\n
What you need is a battery system that's just the right size: not so small that it can't store all the electricity produced by your panels, and not so large that it never gets full.<\/p>\n\n\n\n
<\/div>\n\n\n\n
Do I Need An AC or DC-Coupled System?<\/strong><\/h2>\n\n\n\nWhat's the difference? <\/em>you might ask.<\/p>\n\n\n\nWell, it's all to do with where the battery is located within the system.<\/p>\n\n\n\n
As you may know, AC stands for alternating current<\/em>, while DC stands for direct current<\/em>. With AC, the current flows backwards and forwards from positive to negative, and DC voltage flows only in one direction. AC is better for transmitting over long distances (as there's less energy loss) and is more suitable for running household appliances, which is why UK grid power uses this form.<\/p>\n\n\n\n<\/div>\n\n\n\n
AC-Coupled Systems<\/strong><\/h4>\n\n\n\nWith an AC-coupled system, solar panels send a DC charge to the inverter which converts it to AC for use in the home. But if the energy is not needed, it is sent back to the inverter (sometimes to a separate inverter incorporated into the battery itself) that turns it back into DC form for storage.<\/p>\n\n\n\n
So, with an AC-coupled system, the electricity typically gets converted three times before it is used.<\/p>\n\n\n\n
Overall, these are preferred to the DC system, as they are more reliable and flexible, and it's easier to retrofit them to an existing system. AC-coupled batteries can also be charged by the panels and the national grid, so you are never without power.<\/p>\n\n\n\n
However, they are generally more expensive and not as efficient as DC-coupled batteries because of the need for constant conversion between AC and DC.<\/p>\n\n\n\n
<\/div>\n\n\n\n
DC Coupled Systems<\/strong><\/h4>\n\n\n\nWith these systems, the battery is connected directly to the solar panels before the generation meter or inverter via a charge controller. The charge will only pass through the inverter once when it is turned into AC electricity for your appliances or sent to the grid.<\/p>\n\n\n\n
DC-coupled systems tend to be more affordable (as you probably only need one inverter) and they are more efficient as the charge only has to be inverted once. And, in theory, you can also oversize<\/em> your system, meaning that you can add more solar panels to produce more power than you need using your existing inverter. This extra energy can be used to charge an electric vehicle, a water heater, or a home battery.<\/p>\n\n\n\nThe main downside is that the battery has to be situated close to the panels, so there's less flexibility in this matter.<\/p>\n\n\n\n