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Deep cycle batteries are often used with solar panels for storage. If there is a power outage, the batteries will keep the lights on in your home. But is it possible to use these batteries minus the panels?
Yes, you can use batteries without solar panels. Batteries can store power from the grid, which you can use as backup in case the power goes out.
Why Use Batteries without Solar Panels?
Grid tied solar panels are great for reducing your monthly power bill. It is an efficient, reliable system and pollution free too. This is the reason why usage of solar power continues to increase across the United States.
The only problem is in case of a grid power failure, your solar panels shut down too. This happens automatically to protect those who will repair the transmission lines.
With a battery however, you can have backup power even without solar panels. You can connect a battery like the LNK to the grid and capture energy from it.
In case of a power failure, the battery will supply the power to your home. How many appliances you want to run determines the battery size you will need.
How to Connect a Battery to the Grid
If you don’t have any solar panels or batteries installed and just planning, talk to a solar installer first. They might be willing to set up the battery to charge from the grid on your behalf.
If you already have solar panels installed but want to use batteries as a backup power source, there are three options:
- DC coupling
- AC coupling
- Use a storage-ready inverter
This is the best way to connect batteries to the grid. In an AC coupling, you will need a battery bank, a grid tied inverter and an off grid inverter.
A grid tied inverter has to be on the grid to stay on. If the grid goes down, the inverter would normally shut down too.
But with an off grid inverter, there is now another power source available which keeps the grid tied inverter running. This makes battery charging possible and serve as backup in case of a power outage.
When it comes to AC coupling, Outback Radian has no comparison in terms of performance. As long as your inverter is UL 1741 SA rated it’s going to work.
When the Raiden is installed, it controls the power from the solar panels and grid tied inverter to prevent battery overcharging.
If you want to use batteries without solar panels, AC coupling is the way to go. It works particularly well with microinverters. The Raiden should be installed between the load panels and the grid tied inverter.
In DC Coupling, the solar panels are connected to the batteries and a charge controller. This is the typical set up for an off the grid system.
You need a 600V charge controller like the Morningstar 60A MPPT and a 600V string inverter to make this work. The batteries are charged by the solar panels, with the charge controller providing overload protection.
Use a Storage Inverter
This is the most expensive option because you have to replace your existing grid tied inverter with a storage inverter.
A storage inverter is exactly what it sounds like, an inverter that can store energy from the grid. These are compatible with all solar panel systems and inverters.
The biggest drawback is the cost and the fact that you have to replace your inverter. If you have microinverters, every one of them has to go. This is going to take time and money.
If you want to use batteries to store emergency power, I recommend AC coupling. It is the most cost effective method and the easiest to set up.
Do You Need Solar Panels to Use Batteries?
Batteries are almost always discussed with solar panels that some may assume the two need each other to operate. That is not the case. Batteries and solar panels can run independently of each other.
Solar batteries can gather energy from the grid directly. The benefit of having solar panels is you can use them to recharge the batteries. But if you just want backup power in case the grid goes down, batteries alone will do the job.
On the other hand if you do decide to install solar panels, additional equipment will be required. Aside from the panels, you will also need an inverter to run appliances off solar power.
There are different types of inverters with their own pros and cons. I have written a guide on how to tell the difference between solar inverters and microinverters.
Benefits of Battery Backup Power
The benefits of this system are obvious:
Powder always available. You can have an emergency backup power available anytime. You don’t have to worry about not having your essential appliances in case of an outage.
If a storm is forecast to hit your area, a power failure is possible. You won’t be able to use your solar panels in this situation, but with batteries you will still be able to run essential appliances.
Sometimes it’s just not possible to install solar panels. Perhaps your homeowners’ association has strict building codes. Or you live in a townhouse or condominium.
Some homeowners may only be interested in backup power, not necessarily solar. As I have explained here, you do not need solar panels to use batteries. You can connect the battery to the grid and store power.
Reduced power bill. We know that solar panels reduces your monthly power bill. But batteries can do the same.
You might be living in an area where energy cost hinges on demand. That is, the power company charges more when electricity demand is at its peak.
You can save on costs by charging the battery from the grid. You can configure the battery to activate during peak demand so you won’t get charged the premium amount.
Solar batteries today have smart programming built-in that lets you do this automatically. Over time, these savings are going to be substantial.
What Type of Solar Battery Should I Use?
There are many types of solar batteries, but for household backup power, it comes down to lead acid and lithium ion.
Lead acid. Lead acid batteries are based on older technology. It is inexpensive which makes it popular. But these batteries have a short lifespan and regular maintenance is needed.
I recommend lead acid batteries if you are only going to use it in case of a power outage. Grid failures should only happen a few times a year and these batteries are up to the task.
My choice is the ExpertPower 100ah 12V battery because of its capacity and durability.
Lithium. Lithium solar batteries have higher efficiency and last longer. They are also more expensive than lead acid.
If you are going to use the battery regularly during peak demand, I recommend lithium. These batteries are designed for regular use and can handle the constant charging and discharging. My choice is the DJLBERMPW 12V 200Ah.
If you are still unsure which type to use, here are the other differences between lithium and lead acid batteries.
Price. Lithium batteries cost more to buy upfront. But lithium batteries have a longer lifespan so the cost may even out eventually.
Size, weight, capacity. Lithium batteries have higher capacity but are lighter and take up less space. A 100ah lead acid battery is heavier and larger than a 100ah lithium battery, so keep this in mind if space is a consideration.
Depth discharge. The depth discharge determines how much stored energy can be used before recharging.
Lead acid batteries have a depth discharge of 50%. So if you have a 100ah lead acid battery, you can only use 50ah before it has to be recharged. Completely discharging the battery is going to shorten its lifespan.
Lithium ion batteries have a depth discharge of 85%-100%. You can use almost all of the stored energy without damaging the battery.
I am an advocate of solar power. Through portablesolarexpert.com I want to share with all of you what I have learned and cotinue to learn about renewable energy.