Can You Charge Solar Lights Inside?


It’s quite possible to charge solar lights indoors. Using simple things, you can make your solar lights stay fine even during winters and monsoons without sunlight.

Sunlight is the ultimate energy source for charging solar lights. But some regions do not get sunlight for days during winter and monsoon. For such days can you charge solar lights inside? How to charge solar lights indoors and can you charge solar lights with artificial light?

Why is Sunlight Important for Charging Solar Lights?

You are aware of the importance of sunlight in charging solar lights. The presence of photovoltaic cells enables solar lights to charge sufficiently on a cloudy day also. All it needs is the presence of solar light to charge the batteries. But there are days when the sun does not show, and your solar light battery starts getting exhausted. Solar lights need something subsidiary in such conditions. For this, artificial lights and other ways come in handy.

Can You Charge Solar Lights Inside? 

Yes, you can charge solar lights both indoors and outdoors. If done properly, your solar light will stay fine during winters and monsoons without sunlight. Solar lights are portable light fixtures that mean lights that are powered by the sun. Though the sun is their ultimate source of power, they can also be charged inside the house. Because all we need is to charge their batteries by supplying sufficient heat and light to their solar panels.

1. Parts of a Solar Light

a. Battery: A metal or plastic case houses a set of batteries that has electrodes with cathodes and anodes. Chemical reactions take place in these electrodes. A solar light battery uses gel electrolyte technology that has high performance in deep discharging. This enables it to work smoothly in extreme temperatures. A battery saves power during the day and uses it during the night. Lead-acid, nickel cadmium, nickel metal hydride, and lithium are some commonly used types of batteries.

b. Charge Controller: This protects the battery by regulating the amount of power that reaches the battery. It ensures that irrespective of the reasons the battery does not get overcharged or over-discharged. Additional parts included in a charge controller are a light controller, time controller, temperature compensation, AC transfer switches, sound, lightning protection, and reverse polarity protection. All these parts manage the sensitive backup loads and help the system to work normally during power outages.

c. Solar Panels: They are made out of crystals. Covalent bonds between electrons on the outer shell of the silicon atoms make up solar panels. Silicon is considered both a conductor and an insulator because it does not conduct electricity generally but under certain circumstances, they act as a conductor. There are 2 different layers of silicone in solar panels. The upper layer has more electrons in comparison to the lower layer; the lower layer has a slight positive charge whereas the upper layer has a slight negative charge.

2. Working of Solar Lights

Can you charge solar lights inside? Solar light works on the principle of the photovoltaic effect. The sunlight passing through the upper layer of these photovoltaic cells activates the negatively charged electrons and pushes them toward the positively charged spaces. Multiple solar panels are wired together to form a solar array and the electrons pushed into positively charged spaces form an electrical circuit. Electrons flowing through these circuits generate direct currents.

This current is stored as chemical energy during the day and at night the battery converts this chemical energy to electrical energy. This energy is transferred to the lights and the LEDs are lit up. This way, the solar lights keep illuminated during the night or until the battery power is exhausted, whichever happens first.

3. Types of Solar Light

a) All-in-one Streetlight: There are no cables required for installing this solar light, and it runs on lithium batteries. They are the lightest weight among all. Available capacities are 9W, 5W, 18W, and 24W with a voltage of 12 Volts DC. The solar PV module is 100 Ah.

b) CFL Streetlight: It has a high luminous efficiency and is the brightest on the list. Its capacity ranges are 12W, 15W, 18W, and 24W with a voltage of 12 Volts DC. Its PV (Photovoltaic) module is 74Wp.

c) FLOOD Streetlight: It has the highest luminance and gives you maximum area coverage with fewer units. Their available capacities are 15W, 18W, and 24W with 15 volts of DC voltage. Its solar PV module is 100 Ah.

d) LED Streetlight: It is easy to install and comes with highly refractive acrylic settings. The capacity ranges are 6W, 9W, 12W, 15W, 18W, and 24W with 12 Volts DC voltages. Its PV module can be customized in 37, 40, 75, 100, 125, and 150Wp.

Also See: How Many Batteries Can a 50 Watt Solar Panel Charge?

Can You Charge Solar Lights with Artificial Light?

Another method in which you can charge solar light inside is artificial light. Yes, you can charge solar lights with artificial light. However, the number of bulbs, the watt of the bulb, and their distance from the solar panel define the time and charge. Also, the wattage of solar panels determines the amount of charge their batteries will save from artificial lights. For charging solar lights, incandescent bulbs are preferred because their wavelength is similar to the sun.

1. The Lumens

Since incandescent bulbs are a rare sight nowadays, you can use a light with high lumens because they will be most intense, and this intensity will serve the purpose of sunlight for the solar panels in the solar lights. This way they will be charged efficiently and quickly. The wattage of the bulbs defines their lumens, and a higher wattage means high lumens.

Here is a table to compare the wattage of different types of bulbs and their lumens.

LumensFluorescent Bulbs (Watts)Incandescent Bulbs (Watts)LED bulbs (Watts)

2. Temperature

This is an important factor affecting the efficiency of photovoltaic cells. Maintaining ambient temperature is necessary for receiving the best output from the solar lights or solar power system as a whole. Temperatures higher than 87° Fahrenheit (30.55° Celsius) decrease productivity and extremely high temperatures damage solar panels and reduce their efficiency. Solar lights placed on a dark surface make them hotter during the day, which poses a risk of fire.

How to Charge Solar Lights Indoor?

You were wondering-can you charge solar lights inside? Here are the best possible ways that you can try to charge solar lights indoor-

1. Black Paper

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I know we are talking about solar lights and not about painting a canvas here. However, you can use black paper to boost the charging process of the solar light. According to the source, if you place black paper behind the solar panel, it will absorb more heat and light. This enables them to get charged faster as black is a good absorber of heat and light. Ensure that the paper is not blocking any of the air vents.

2. Incandescent Lights

These are considered the most effective and affordable. You can charge the solar lights by placing their solar panels close (but not too close) under the direct light of the incandescent bulbs. This way the batteries will be charged, and your light will work. But this method may not be effective for all solar lights.

3. LED Light

Before you begin, check the spectrum and wavelength of the LED light you are using to charge the solar light. A short wavelength is not sufficient to charge the lights. An LED with a high Kelvin rating produces more blue light and can precisely charge the solar light, otherwise, a white LED may do the work.

4. Magnifying Glass

A magnifying lens could also charge the solar lights. You remember the sun and magnifying experiment you did back in school. Similarly, place the lens over the solar panel and focus the sunlight on the panel. In this way, the amount of light received by the panels will be higher in intensity. Batteries will be charged faster, but do not place the lens too close to the panels. Also, in this method, you need to do this for 3-4 hours.

5. Mirror

Can you charge solar lights inside with a mirror? Sometimes you cannot place the panels outside due to certain reasons. You can redirect the sunlight with the mirror if you want to charge the solar light indoors. Place the mirror behind the solar panel, tilt it, and adjust the angle such that the sunlight is reflected on the panels. Use big mirrors for this purpose.

6. Reflector

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A solar reflector is also a great option as it helps in charging the batteries faster. It works in the same way as a mirror but more effectively. Place it behind the panel such that it does not block any air vent as it can overheat the solar lights.

7. Solar Charger

Solar panel
Image on Walmart.com

It is specifically designed for this purpose, and it comes in handy while charging solar lights inside the house. Check the compatibility of the solar charger with the solar light batteries. Place the panel of the solar charger in a sunny spot, and it will charge the batteries of solar lights. A solar charger with in-built batteries needs to be charged first before you charge solar lights with them.

8. Window

You know solar panels need sunlight. Placing the panels near or on the balcony where the panels receive direct sunlight will charge the lights. If possible, place the panel on a south-facing window and ensure there is no obstruction.

9. Flashlight

Yes, it is capable of charging solar lights. However, the speed and time taken to charge are depended on the brightness of the flashlight. A flashlight emits 100 lumens on average, which means it will take longer to charge the solar lights. If compared to a sunny day the strength of a flashlight lumen is just 1%, and it is 6.7% stronger in comparison to a cloudy day. After this, let’s move towards learning-can solar lights charge in shade.

Also Read: How Do Solar Lights Turn On At Night?

Can Solar Lights Charge in Shade?

Can you charge solar lights inside in the shade? Yes, it is possible for solar lights to get charged in shade also. But the term shade has varying degrees depending on the amount of sun rays received there. Light sensors present in solar panels enable them to identify the presence and absence of light. A solar panel getting shaded by the tree is not affected much as it will receive enough sunlight to charge its batteries. But if a panel is covered like a garage shade, then it will not charge efficiently.

Make sure that the panels are getting at least 6-8 hours of solar energy because they usually have a 4-hour charge cycle.

Importance of Angle

Placement and angle are equally important for charging solar lights as sunlight. A properly placed solar panel will charge the lights faster. The best angle is 45° to place the solar panels. This will ensure enough sunlight is received by the panels but ensure there is no obstruction after you adjust the angle.

Well, can you charge solar lights inside? Now you know that it is possible to do so with the right placement and distance while keeping other parameters in the right ratio. Do you know how to charge solar lights indoors by any other means? Can you charge solar lights with artificial light? Have you tried it yet? Can solar lights charge in shade? Yes, they can, but the angle, temperature, solar panel capacity, and other things determine how much the batteries will be charged.

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