How to Connect Solar Panels to Battery

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The sun is hot, and solar panels are awesome. However, despite it being one of the most powerful forces on our planet when it comes to powering your home, you may be a little disappointed at times. 

You’ll need electricity when it’s not sunny out, which means you need batteries to store the energy generated by your solar panels for later use. Solar panels only produce power during certain times of day and can’t store energy for later use in batteries. Luckily for us, there are ways to work around this problem! 

We’ll go over how to connect solar panels to batteries so that you can harness all that sunlight and keep producing electricity even after the sun goes down. We will also cover how these batteries work? And what types of battery connections can you apply. 

In this post, we will talk about how to connect solar panels to batteries so that even on cloudy days or at night, your home has access to abundant electricity!

Can I Connect Solar Panels Directly to Battery?

Yes, you can connect solar panels directly to batteries. However, you should know that inverters cannot charge batteries because they convert DC electricity into AC. So, if you want to store energy for later use, you need a battery bank and an inverter must be used between the PV array and the battery bank so power can flow both ways. The inverter will also allow your appliances inside of your home to run off of solar power during the day. 

With this configuration, the only time when the grid is used is during night hours or cloudy days when there isn’t enough sunlight hitting the solar panels to generate adequate amounts of electricity for your home. At other times during sunshiny days, the grid is cut off and your home runs on solar power entirely.

So, if you want to benefit from a battery bank as well as have appliances run off of electricity generated by solar panels during sunshiny days, then the only way to do this is with an inverter. In that case, you can connect the PV array directly into the battery using a combiner box that will tell the inverter when to draw from solar panels or from batteries. 

You should also know that an energy management system can be used to ensure all of these different components are working together so they don’t conflict with each other.

Combo Box: A device used for safely joining two or more conductors without a splice and providing overcurrent protection for each conductor. A metal or plastic box containing one or more sets of spring-loaded interchangeable fuses, designed to protect the conductors of a circuit from overloads and short circuits.

Combiner Box: A device used for safely joining two or more conductors without a splice and providing overcurrent protection for each conductor. A metal or plastic box containing one or more sets of spring-loaded interchangeable fuses, designed to protect the conductors of a circuit from overloads and short circuits.

Battery Bank: The combination of batteries that provides power in an off-grid system; also called storage bank, energy storage bank, power storage bank, battery stack, battery array.

Things You Will Need:

Supplies

Renogy 2PCS 100 Watt Solar Panels 12 Volt Monocrystalline, High-Efficiency Module PV Power Charger for RV Battery Boat Caravan and Other Off-Grid Applications, 2-Pack Compact Design

Solar Panels

NOCO GENIUS1, 1-Amp Fully-Automatic Smart Charger, 6V and 12V Battery Charger, Battery Maintainer, Trickle Charger, and Battery Desulfator with Temperature Compensation

Battery Charger

300W Power Inverter DC 12V to 110V AC Car Charger Converter with 4.8A Dual USB Ports (Blue)

Power Inverter

Single Hole - ADR2 Aluminum Mechanical Lug 50 Pieces

Mechanical Lugs

2 Gauge 2 AWG 5 Feet Black + 5 Feet Red (10 Feet Total) Welding Battery Pure Copper Flexible Cable Wire - Car, Inverter, RV, Solar by WindyNation

2 AWG Cable

Battery Terminal Clamp Connectors, LYCARESUN 2Pcs 4 Way Positive Negative Car Battery Terminals Connector Quick Release Disconnect for SAE/JIS Type A Posts…

Battery Terminals

Tools

Klein Tools 32500 Multi-Bit Screwdriver / Nut Driver 11-in-1 Multi Tool, 8 Industrial Strength Bits, 3 Nut Driver Sizes, Cushion Grip Handle

Screwdriver

Muzata Cable Cutter Wire Rope Heavy Duty Stainless Steel Aircraft Up to 5/32" for Deck Stair Railing Strong Thick Seal Metal Fencing Bike Bicycle Brake Cutter with 6Pcs Ferrules CR12, CT1

Cable Cutters

BLACK+DECKER 20V MAX Cordless Drill / Driver with 30-Piece Accessories (LD120VA) , Orange

Drill

Scotch Vinyl Color Coding Electrical Tape 35, 3/4 in x 66 ft, Red

Red Electrical Tape

Crescent 6" Adjustable Black Oxide Wrench - Carded - AT26VS

Crescent Wrench

Steps to Connect Solar Panel to Battery

Prepare tools, materials and batteries before you begin

The batteries must be prepared by charging them with a charger. Before putting the batteries in the container, you should make sure they are fully charged. The positive (+) terminals should be on one side and the negative (-) terminals on another.

Make the jumpers

The next step is to make jumpers from terminal to terminal after the batteries are in place. The batteries are most often connected in parallel to protect the panel’s voltage. To do so, measure between terminals and use a 2 AWG cable to create the jumpers.

Alternatively, you may wire the panels together in a series to increase the voltage. The voltage is increased so that it matches that of the battery bank. Just make sure the panel outputs are comparable to those of the battery bank.

Prepare the cover

To connect the panel’s leads to a charge controller and inverter, drill holes in the lid. Depending on your preference, you may choose to keep your charge controller inside or outside of the box.

Hook up the charge controller onto the lead battery

The charge controller and inverter must now be linked to the battery cables. Before you begin, double-check that the charge controller isn’t connected to the solar panel and that the inverter is not switched on.

When connecting your solar panel to a charge controller, it is very important to connect the panel’s adapter kit first. After that, match the positive (+) or negative (-) leads of the panel with those of the charge controller. Make sure the panel is firmly seated; otherwise, you risk having reverse polarity and a short in your system, which can harm both controllers and panels.

It’s also crucial to remember that a good charge controller will assist in reducing the panel’s voltage changes and providing a consistent charging voltage for the batteries. It also protects the panels from current backflow caused by the batteries, as well as preventing an overcharge of the cells.

Attach the batteries to the solar inverter

The final step is to connect the battery bank to the inverter’s input lugs. Then connect the inverter to your house panel and make sure it works correctly. At this stage, the inverter converts DC current from the batteries into 110-volt AC electricity that will be used in your home panel.

The inverter can also be programmed to give excess power to the power utility if the house panel is connected to the electricity grid.

How Long to Charge 12V Battery with 100-Watt Solar Panel

How long it will take to fully charge the battery with 100 watts of solar power varies on many factors, including weather conditions and time of year. For example, if you live in an area where there is little sun during the winter months, you won’t be able to get as much energy into your battery bank.​​ 

Here are some​​guidelines for how many hours it takes to charge batteries at various wattages:

12-volt batteries at 20-amp hours each – about 6 hours total (assuming 5 hours of good sunlight) 

6-volt golf cart batteries at 125-amp hours each – about 22 1/2 hours total (assuming 5 hours of good sunlight) 

Larger capacity batteries will obviously take longer than smaller ones.

Frequently Asked Questions 

Where should the solar panel be positioned in relation to the sun?

The solar panel should be facing direct sunlight and tilted at a 45-degree angle to allow for maximum sunlight.

Is it possible for me to have my solar panels function on overcast days?

Yes, to an extent. Generally speaking, the cloudier the sky, the less energy is collected from your solar panels. On a completely cloudy day, you can expect about 7-15% of what it would be on a sunny day. 

When is the best time to utilize solar panels on any given day?

Generally speaking, the best times to utilize solar panels are between 10 am and 3 pm. This is when the sun is at its highest point in the sky which gives it greater intensity for charging your batteries.

Is it possible for my solar panels to be charged when they are partially shaded?

No, if anything is shading your panels it should be moved. However, you can use this to your advantage and utilize your solar panel as a shade for plants and animals on hot days!

Conclusion

The most important thing to remember when hooking up your solar panels is to make sure you are always double-checking the connections. When connecting the cables, it’s very easy to reverse them, which would cause damage to both the solar controller and battery bank. It’s also crucial that you check that all leads are connected properly before plugging in the inverter.

Once everything is properly connected, your system should function just as well as a grid-powered one! Enjoy free electricity for years to come. 

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