Recharging Batteries with Solar Power

The sun has unlimited power. Solar panels allow people to harness this power and use it for all sorts of electrical applications. One of these is storing energy for future use.

The cost of disposable batteries is much higher, over time, than that of rechargeable batteries, and this cost difference widens when the recharging is done with solar power.

Batteries can be recharged with a solar panel, or with a solar-powered charger made for that purpose. The charger is the easier option, as it comes already ready to use. Using solar panels involves a bit of setup, but once that is completed, it should last indefinitely.

Solar Panel

To use a solar panel, first check the back of it to see how many watts it outputs. If the solar array was self-created, a multimeter will allow measurement of the panel’s output; check it during full sun exposure. It wouldn’t hurt to use the multimeter even on a commercial panel, as they are designed for higher production than the rating, because the max rating only happens if the conditions are ideal, which does not happen often. It is necessary to know this because if the panel’s power exceeds the battery’s capacity, it can overcharge the battery, which will damage it or cause it to explode.

To determine the amp requirement, divide the watts determined above by the battery voltage. The result is the charge controller rating that is required. Because controllers are generally rated in multiples of 30, round up if the result falls between ratings.

Charge controllers come in two types: MPPT (Maximum Power Point Tracking) and PWM (Pulse Width Modulation). While both will serve the purpose, an MPPT controller tends to be more effective and can be used with panels set up in strings, unlike PWM controllers. However, PWM are less expensive and good starter controllers; they charge with pulses and have a sensor to prevent overcharging. Those starting with a PWM can easily switch to an MPPT later, if desired.

Controllers usually are susceptible to weather, so they should be mounted somewhere protected, with wires running between it and the panel. For safety, mount it on something non-conductive.

Connect wires to the battery – one on each pole. For convenience and ease in differentiating, it is wise to use different colored wires for each. Attach the other end of the wire to the charge controller, following the controller’s instructions. Be careful to make sure the positive and negative match the port to prevent a short circuit. For larger batteries, such as 12V, use larger wire, such as 10 or 16 gauge.

To prevent a surge when connecting to the controller, connect the battery first, then the solar panel.

Most solar panels have MC4 connectors on their output wires. Use wires with MC4 connectors to go from the controller to the solar panel; instructions are usually included with the connectors. Once they are in place, connect them to the solar panel, being careful to connect positive with positive. Connect the MC4 connectors securely; they should click into place.

Once it is connected, verify the readings to be sure it is working properly. If there is nothing displayed on the controller’s screen, check the wires to be sure they are connected properly. Depending on the controller, it may be possible to monitor it through a mobile device.

Do not remove the battery until it is fully charged. A controller will stop allowing energy through once the battery is charged, so it is not necessary to remove it immediately. The display will show less (or no) charge going through once the battery is full.

Solar Chargers

Solar chargers are portable and easy to set up. They usually hold and recharge up to four batteries at a time of standard sizes. Some of them include a port to recharge mobile devices such as smartphones and tablets, and some of those can charge more than one device at a time. Chargers with a higher watt output will charge more quickly. If the charger has a built-in power bank, it will be able to provide a charge even in cloudy conditions, which can be a definite advantage. Those that come with foldable solar panels can provide more power at the same portability as smaller chargers.

Product

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Where to Buy

PowMr MPPT Charge Controller 60 amp 48V 36V 24V 12V Auto - Max 190VDC Input LCD Backlight Solar Charge for Vented Sealed Gel NiCd Lithium Battery【Software Update Version】(MPPT-60A)

20A Solar Charge Controller Solar Panel Battery Intelligent Regulator with Dual USB Port 12V/24V PWM Auto Paremeter Adjustable LCD Display

Kohree Solar Crimping Tool for MC4 / MC3 Cable Connector, with 6pcs Male Female Solar Connector + 2pcs Spanners Wrench + 1pcs Wire Crimper + 1pcs Tool Kit for 2.5/4/6mm² Solar PV Wire

WindyNation 10 Gauge 10 AWG One Pair 30 Feet Black + 30 Feet Red Solar Panel Extension Cable Wire Solar Connectors

Temco 1 Pair 100 ft MC4-Compatible Solar Panel Extension Black + Red Connector Male Female 10 AWG Gauge PV Cable Wire

GS Power 100% Copper 16 AWG (American Wire Gauge) Stranded Flexible Dual Conductor Bonded Zip Cord Cable for Car Amplifier Automotive Trailer Harness Hookup Wiring – 100 feet Red/Black

Solar Charger, 25000mAh Battery Solar Power Bank Portable Panel Charger with 36 LEDs and 3 USB Output Ports External Backup Battery for Camping Outdoor for iOS Android (Black)

Resources

Charge controller (MPPT)

This 60a charge controller can be used in parallel with another to increase the amperage; however, they must be the same controller brand and type to work properly. It comes with instructions on how to connect it. It has an LCD display to show voltage, current, mode, and temperature, as well as to assist in troubleshooting, if needed.

Charge controller (PWM)

This 20a controller has multiple protection options along with an easy to read LCD screen that shows status and other information. Buttons on the front allow for easy mode changes and parameter configuring. Install in a well-ventilated location, as the controller does get hot when running.

MC4 connectors

This set comes with a wire crimper to add the MC4 connector to a wire end. Six connectors are included, along with two solar connector spanners.

Premade 10 Gauge Wire:

One black and one red, both 10 gauge, already have the MC4 ends on them. They are 30 feet long.

100-foot MC4 Compatible Wire

One black and one red 10-gauge wire with ends already installed are 100 feet long.

16-Gauge Wire

For higher volt batteries, this 16-gauge wire is a better option for safety.

Solar Charge Power Bank

The power bank’s 25000mAh Li-polymer batteryhas 3 USB output ports to charge mobile devices. The power bank also has LED lightsfor emergency use.

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Where to Buy

[Upgraded]BigBlue 3 USB Ports 28W Solar Charger(5V/4.8A Max), Foldable Portable Solar Phone Charger with SunPower Solar Panel Compatible with iPhone 11/Xs/XS Max/XR/X/8/7, iPad, Samsung Galaxy LG etc.

POWOXI 7.5W-Solar-Battery-Trickle-Charger-Maintainer -12V Portable Waterproof Solar Panel Trickle Charging Kit for Car, Automotive, Motorcycle, Boat, Marine, RV, Trailer, Powersports, Snowmobile, etc.

Solar AA & AAA Rechargeable Batteries Charger for 1.2V AA AAA NiMH NiCD & 9V Battery with 2Watt Solar Panel Portable Backup for 1.2V Ni-MH Ni-CD of Solar Powered Lights and Household Battery

Solar 11-in-1 Battery Charger

AmazonBasics AA High-Capacity Ni-MH Rechargeable Batteries (2400 mAh), Pre-charged - Pack of 8

AmazonBasics AAA Rechargeable Batteries (800 mAh), Pre-charged - Pack of 12

Solar Charger with Panels

Multiple panels and three USB ports make this a speedy power charger for mobile devices. Water resistant to protect from weather, the ports have a cloth and rubber cover to keep them from becoming damaged when not in use. This panel does not include a battery, but plugs directly into the item being charged.

Trickle Charger

This solar charger is powerful enough to charge 12V batteries, car batteries, marine batteries, and more. It does not have a built-in battery; attach when sunlight is available to charge. However, a valve keeps the panel from discharging a connected battery if sunlight is scarce. It will take some time to fully charge a battery, but if a vehicle is being stored, this will prevent the battery from discharging on its own from not being used.