20-Watt Solar Panel Guide: Price, Working, Types, Pros, Cons

A 20-watt solar panel is a compact PV module that can generate 20 watts of DC output under standard test conditions (STC). It’s usually designed to be compatible with a 12-volt battery system and can be easily carried in a backpack to supply emergency charging while hiking or camping in remote and off-grid locations.

Outside labs in the real world, on a bright and sunny day, a 20-watt solar panel can produce up to 18 volts. However, if you’re looking at these panels as options to mount on-grid solar systems or off-grid solar systems to power heavier loads, these panels aren’t suitable for the purpose. Higher wattage modules are used to build kW-scale solar systems, not low-wattage ones like 20 watt or 10-watt solar panels. 

The 20-watt solar panel price in India in 2025 by premium solar panel manufacturers can range between ~Rs. 1,200* to ~Rs. 2,500* for modules with polycrystalline cells and ~Rs. 2,000* to ~Rs. 4,000* for modules with monocrystalline solar PV cells.

*Please note: The above-mentioned solar plate prices are indicative and not fixed. The final 20-watt solar panel price can significantly vary, depending on panel type, brand, cell technology used, market demand of the module, promotional offers by the manufacturer, etc. The final cost can be significantly lower or higher based on the brand’s reputation for building quality products. SolarSquare does not manufacture, sell, or endorse any particular 20-watt panel brand. We install on-grid rooftop solar for housing societies, homes, and commercial buildings using higher-wattage solar panels.

In this blog, we’ll explain the working, types, uses, pros, cons, and cost of 20-watt solar panels. We will walk you through the reasons why they aren’t suitable for building kW-scale solar energy systems and whether or not you should invest in installing on-grid rooftop solar panel systems for homes, housing societies, and commercial complexes. 

TL;DR Summary Box: What Can a 20-Watt Solar Panel Run?

A 20-watt solar panel can be used to charge a 12-volt battery system for boats, bikes, and cars. It produces enough power on a sunny day to charge small gadgets like smartphones, power banks, LED lights, and emergency flashlights. However, these panels can’t be used to charge bigger appliances and gadgets like ACs, water pumps, and laptops. 

On a sunny day, a 20-watt panel produces about 18 volts. When charging a lithium battery through a solar panel charge controller, the battery is charged at about 13 to 14.6 volts.

Here are the key topics we’ve explained in detail in this blog:

Main Topics	Quick Takeaways
How does a 20-watt solar panel work?	Solar cells in a 20-watt solar panel absorb sunlight and convert it to DC power.
What are the types of a 20-watt solar panel?	Polycrystalline and monocrystalline panels
20-watt solar panel price in India in 2025	~Rs. 1,200* to ~Rs. 2,500* for modules with polycrystalline cells ~Rs. 2,000* to ~Rs. 4,000* for modules with monocrystalline cells
What are the benefits of a 20-watt solar PV panel?	They are lightweight and can be used to charge electronics like phones, power banks, and flashlights in remote and off-grid locations.
What are the drawbacks of a 20-watt PV panel?	The output is weather-dependent, and the panels can’t be used to build kW-scale solar energy systems.
What are the applications of a 20-watt solar panel?	They can be used to charge a 12-volt battery for cars and boats. You can use them as emergency power supply options in remote locations.
Is 20 watts enough to build a kW-scale solar system?	No.
Is it worth installing an on-grid rooftop solar system at homes?	Yes. Rooftop solar systems can reduce your electricity bills by at least 90% and save tens of lakhs of rupees in 25 years of their life.

*Please note: The above-mentioned solar plate prices are indicative and not fixed. The final 20-watt solar panel price can significantly vary, depending on panel type, brand, cell technology used, market demand of the module, promotional offers by the manufacturer, etc. The final cost can be significantly lower or higher based on the brand’s reputation for building quality products. SolarSquare does not manufacture, sell, or endorse any particular 20-watt panel brand. We install on-grid commercial rooftop solar systems and those for homes and housing societies using higher-wattage panels. 

What is a 20-Watt Solar Panel and How Does it Work?

A 20-watt solar panel is a PV module rated to make 20 watts of DC power under standard test conditions. In real life, you’ll often see less output, depending on sunlight and temperature. Most 20-watt modules have 36 solar cells arranged in a grid-like pattern. The power they produce can be used to charge small electronic items and a 12-volt lithium battery.

On a bright and sunny day, with nothing connected, the voltage output from the panel can be ~22 volts. If you connect this same panel to charge a 12-volt battery, the voltage will be 13 to 14.6 volts. 

How Does a 20W Solar Panel Work?

Solar cells in a 20-watt solar panel absorb photons present in the sunlight and use the photovoltaic effect to convert this sunlight into DC (direct current) power.

Let’s understand how this sunlight-to-DC conversion happens step-by-step:

• Step 1 – Photons in the sunlight get absorbed: The solar cells in a 20-watt solar panel are usually made of silicon, which is a semiconductor material. These cells absorb photons.  
• Step 2 – The photons absorbed transfer their energy to electrons: Electrons in silicon cells leave their place once they receive the energy from photons and begin moving. Thus, every single photon that knocks an electron loose produces an electron-hole pair. 
• Step 3 – The built-in electric field results in the production of usable voltage: The electric field in the p-n junction of the solar cell keeps the charged pair of electrons and holes away from each other by pushing them in the opposite direction instead of letting them recombine. The flow of electrons in itself is electricity.
• Step 4  – DC power generated flows in one direction only: Metal contacts collect the charges. When you connect a device or battery, electrons flow through the external circuit as DC power.
• Step 5 – The DC power is used to charge batteries and gadgets: A charge controller or regulator sets the right output for what you’re charging. Whether it’s a battery or a gadget, they shouldn’t be connected straight to the solar panels because the DC output they produce varies throughout the day. This voltage fluctuation can damage your devices. Therefore, always use a charge controller, preferably an MPPT solar charge controller, to charge your devices safely. 

What Are the Types of a 20-Watt Solar Panel?

20-watt solar panels can be classified into two main types, depending on the types of solar cells used. The main types are polycrystalline solar panels, which use less efficient poly cells, and monocrystalline solar panels, which use the more efficient mono cells. 

Let’s understand how these two types differ: 

Feature	20-Watt Polycrystalline Panels	20-Watt Monocrystalline Panels
Definition	A polycrystalline panel is composed of poly cells that are made by melting pieces or fragments of silicon and casting the molten silicon into a block that solidifies with many small crystals. Thin slices are cut from this block to make the cells.	A monocrystalline panel is composed of mono cells that are cut from a single-crystal silicon ingot, which is pure and unbroken. Their efficiency is higher than that of poly cells.
Efficiency	16-17%	19-20%
Lifespan	20-25 years	30-40 years
Price range	~Rs. 1,200* to ~Rs. 2,500*	~Rs. 2,000* to ~Rs. 4,000*

*Please note: The above-mentioned solar plate prices are indicative and not fixed. The final 20-watt solar panel price can significantly vary, depending on panel type, brand, cell technology used, market demand of the module, promotional offers by the manufacturer, etc. The final cost can be significantly lower or higher based on the brand’s reputation for building quality products. SolarSquare does not manufacture, sell, or endorse any particular 20-watt panel brand. We install on-grid rooftop solar systems for housing societies, homes, and commercial or industrial buildings using higher-wattage solar panels.

While bifacial solar panels are the most-recommended types of PV modules, this variation is not available for low-wattage 10- or 20-watt solar panels. Bifacial modules come in higher-wattages and are widely used in building kW-scale solar energy systems for residential and commercial installations.  

What is the 20-Watt Solar Panel Price in India in 2025?

The cost of 20-watt solar panels largely depends on whether you opt for panels with polycrystalline cells or monocrystalline cells. Poly cells, being less efficient, are cheaper than mono cells.

Here’s the estimated 20-watt solar panel price range in India in 2025 by high-end and reputable brands:

Type of Panel	20-Watt Solar Panel Price in India in 2025*
20-watt polycrystalline solar panel	~Rs. 1,200 to ~Rs. 2,500
20-watt monocrystalline solar panel	~Rs. 2,000 to ~Rs. 4,000

*Please note: The above-mentioned solar plate prices are indicative and not fixed. The final 20-watt solar panel price can significantly vary, depending on panel type, brand, cell technology used, market demand of the module, promotional offers by the manufacturer, etc. The final cost can be significantly lower or higher based on the brand’s reputation for building quality products. SolarSquare does not manufacture, sell, or endorse any particular 20-watt panel brand. We install on-grid rooftop solar systems for homes, housing societies, and commercial or industrial buildings using higher-wattage solar panels.

Is a 20-Watt PV Panel Ideal for Rooftop Solar Systems?

A single 20-watt solar panel can produce only up to 20 watts of DC output under perfect sunlight. This power output is too small for building a kW-scale solar energy system. 

If you were to use 20-watt solar panels to build something as small as a 2 kW solar system, you would need 100 solar panels to reach the desired capacity. The practical issues here are:

• Added complexity and cost: Wiring hundreds of panels to reach the desired capacity will be too complex. A lot of added wiring and support would be needed. This will make the installation a lot more expensive and complicated.
• A lot of free and shadow-free space on the roof will be needed: Combining hundreds of panels would require significant shadow-free space on the rooftop. And most homes won’t have that much free space.

Let’s give a simple side-by-side comparison of the number of 20-watt solar panels vs the number of 550-watt solar panels that are needed to build a kW-scale solar system:

Solar System Size	Number of 20-Watt Solar Panels Needed	Number of 550-Watt Solar Panels Needed
2 kW solar system	100	4
3 kW solar system	150	6
4 kW solar system	200	8
5 kW solar system	250	10
10 kW solar system	500	19

Please note: The number of solar panels needed to build a solar system = solar system’s capacity in watts divided by the module’s capacity. 

Needless to say, building a solar system out of higher-wattage solar panels is a lot more practical and cost-effective. Low-wattage solar panels are not used to build such large solar systems. 

What Are the Applications/ Uses of a 20-Watt Solar Panel?

A 20-watt solar panel can be used as a power charging station for small gadgets and a battery maintenance module to trickle charge batteries in boats and cars. 

Let’s check all the applications of a 20-watt solar panel in detail:

• Handy for RVs and boats: They can trickle-charge a 12-volt battery during the day so LED lights and small gadgets can be powered or charged at night or under cloud cover.
• Power backup options in tiny off-grid sheds: They can run LED lights, charge a power bank, or keep a small Wi-Fi dongle charged in good sun.
• They can light up gardens and backyards: You can use them to charge a battery for path lights, fairy lights, or a small fountain pump timer. 
• Ideal for camping in off-grid locations: They provide power to keep necessary gadgets like phones and flashlights charged while camping or hiking in remote locations with no grid supply.

What Are the Benefits of a 20-Watt PV Solar Panel?

20-watt solar panels are a great portable option for providing power to charge essential gadgets like phones, batteries, and power banks in remote areas with no grid supply. You don’t have to worry about discharged phones or dead batteries with these panels by your side while hiking or camping. 

Let’s check out all the major benefits of a 20-watt solar panel in detail:

• They are portable: 20-watt solar panels can weigh up to 2 kgs, unlike larger modules that are too heavy to be portable. Therefore, you can simply slip a 20-watt PV panel inside your backpack. Plus, since they’re lightweight, you don’t need any safety gear to lift them. They can be easily mounted on top of RVs to supply enough power to keep the LEDs running.
• They offer reliable power to charge small devices: With a charge controller (or built-in USB), they can charge phones, power banks, LED lights, small Wi-Fi routers, and flashlights in the sun. 
• They can charge 12-volt battery systems: Works well as a trickle/maintenance charger for car, bike, or small boat batteries
• They do not cause noise pollution: Solar panels do not emit sound while working. Hence, they do not cause noise pollution. 
• They are eco-friendly: Solar panels use sunlight to generate electricity. This ensures no carbon is released into the atmosphere. 
• They’re easy to maintain: There are no moving parts in 20-watt solar panels. If you keep their surface clean by wiping it, the panels will work for a long time. Hence, maintaining them is very cost-effective.

What Are the Drawbacks of a 20-Watt Solar Panel?

A 20-watt solar panel’s output can drop significantly on a cloudy day, as the power output depends on how much sunlight is available. Also, since their maximum DC output under STC is 20 watts, they’re unsuitable to run large appliances and gadgets like ACs and TVs.

Let’s check out all the disadvantages/ drawbacks of 20-watt solar PV panels:

• The power they produce is too low for large electronics: A 20-watt power output is insufficient to run ACs, fridges, pumps, TVs, or most laptops.
• The charging speed is slow: A 20-watt panel will charge small gadgets, but it will do that slowly. It won’t offer fast charging that wall chargers can offer. Also, it only trickle-charges a 12-volt battery.
• The output is weather-dependent: Clouds, shade, mornings/evenings, and winter sun significantly reduce the output.
• Extra parts add to the cost: In most cases, you will need a charge controller or a regulator since output from panels can’t be used directly to charge gadgets or batteries. This will be an added expense.  

What Are the 20-Watt Solar Panel Specifications?

Here are the key specifications of most rigid models of 20-watt solar panels:

20-Watt Solar Panel Specifications	Details*
Power output (STC)	20 watts
Weight	Up to 2kgs
Voltage at best output	~18 volts
Number of solar cells	~36
Cell type	Polycrystalline or monocrystalline

*Please note: These specifications are typical for fixed 20-watt solar panels, not the foldable models. Actual specifications can also vary significantly by brand and model. Always use the manufacturer’s datasheet for exact values. 

What’s the Cost of Installing an On-Grid Rooftop Solar System in India in 2025?

Installing an on-grid solar system in India can cost between ~Rs. 90,000* in Lucknow for a 2 kW solar system and ~Rs. 5.62 lakh* in Bengaluru for a 10 kW solar system after you get a subsidy under the PM Surya Ghar Muft Bijli Yojana. 

*Please note: The above-mentioned solar plate price is indicative as of 17th August 2025 for the SolarSquare Blue 6ft variant. The final cost for solar PV systems depends on your DISCOM charges, product variant opted for, panel type, inverter type, mounting structure height, type of after-sales service, savings guarantee, roof height, etc. Prices are subject to change. 

Here’s a tabulated snapshot that compares the installation cost in India with and without a subsidy:

Solar System Size	Solar Panel Price in India Without Subsidy (Starting price – Indicative for base variant)*	Solar Panel Price in India With Subsidy (Starting price – Indicative for base variant)*
2 kW solar system	~Rs. 1.8 lakh in Lucknow to ~Rs. 2 lakh in Bengaluru	~Rs. 90k in Lucknow to ~Rs. 1.40 lakh in Bengaluru
3 kW solar system	~Rs. 2.10 lakh in Lucknow to ~Rs. 2.35 lakh in Bengaluru	~Rs. 1.02 lakh in Lucknow to ~Rs. 1.57 lakh in Bengaluru
4 kW solar system	~Rs. 2.55 lakh in Lucknow to ~Rs. 2.85 lakh in Bengaluru	~Rs. 1.47 lakh in Lucknow to ~Rs. 2.07 lakh in Bengaluru
5 kW solar system	~Rs. 3.10 lakh in Lucknow to ~Rs. 3.70 lakh in Bengaluru	~Rs. 2.02 lakh in Lucknow to ~Rs. 2.92 lakh in Bengaluru
10 kW solar system	~Rs. 5.80 lakh in Lucknow to ~Rs. 6.40 lakh in Bengaluru	~Rs. 4.77 lakh in Lucknow to ~Rs. 5.62 lakh in Bengaluru

*Please note: The above-mentioned solar plate price is indicative as of 17th August 2025 for the SolarSquare Blue 6ft variant. The final cost of installing an on-grid rooftop solar panel system at home depends on your DISCOM charges, product variant opted for, panel type, inverter type, mounting structure height, type of after-sales service, savings guarantee, roof height, etc. Prices are subject to change. 

Initial Installation Cost vs Solar Savings in 25 Years

Installing a rooftop on-grid solar system reduces electricity bills by at least 90%. Considering the fact that the electricity tariffs increase by 3-6% annually, no matter your city, the savings that a solar system makes for you over 25 years of its life are in the tens of lakhs of rupees. 

Let’s give you a head-on comparison between installation cost vs savings from solar in 25 years in Nagpur:

Solar System Size	Solar Panel Price in Nagpur With Subsidy (Starting Price – Indicative for Base Variant)*	Solar Savings in Nagpur in 25 Years*
2 kWp	~ Rs. 1.15 lakh	~ Rs. 11.05 lakh
3 kWp	~ Rs. 1.32 lakh	~ Rs. 16.58 lakh
4 kWp	~ Rs. 1.77 lakh	~ Rs. 22.11 lakh
5 kWp	~ Rs. 2.27 lakh	~ Rs. 34.43 lakh
10 kWp	~ Rs. 5.02 lakh	~ Rs. 68.86 lakh

*Please note: The above-mentioned solar plate price is indicative as of 17th August 2025 for the SolarSquare Blue 6ft variant. The final cost of installing an on-grid rooftop solar panel system at home depends on your DISCOM charges, product variant opted for, panel type, inverter type, mounting structure height, type of after-sales service, savings guarantee, roof height, etc. Prices are subject to change. Additionally, while calculating savings, we have considered the annual tariff escalation at 3% and the annual degradation at 1%. The actual final savings from solar panel installation depend on the types of solar panels you’ve installed and their efficiency, intensity of sunlight your rooftop receives, orientation of the panels and tilt angle, the pollution level and weather conditions in your city, the temperature, shadow on the roof, impact of dirt/dust, and how well you maintain your panels after installation.

Impressed by the savings that a solar system offers? Want to check how much money you will be able to save by going solar in your city? Use SolarSquare’s free rooftop solar calculator to get an estimate.

Conclusion

A 20-watt solar panel can produce up to 20 watts of DC output, which is sufficient to trickle charge a 12-volt lithium battery and/or keep small gadgets like smartphones, power banks, and LED lights running in off-grid locations. Since they weigh up to 2 kgs, you can easily keep them in your backpack and carry them while hiking or camping. 

However, if you’ve been exploring the cost of 20-watt solar panels with the intention of using them for building a rooftop solar system at your home, you’ll need higher-wattage solar panels for that. 20 watts is too small and impractical for kW-scale solar systems. For any further queries, book a free solar consultation with SolarSquare today. 

FAQs

Q1. Can a 20-watt solar panel charge a phone?

Ans. Yes, a 20-watt solar panel can easily charge a smartphone. However, you’ll need a charge controller or regulator for safe charging since the panel's output can’t be used to charge gadgets directly.

Q2. How fast will a 20W solar panel charge a 12V battery?

Ans. It can take about 6 hours to even days to charge a 12-volt battery with a 20-watt panel. It’s best for topping up/trickle-charging, not fast charging. Actual time is too subjective as it depends on battery size and sunlight.

Q3. How many amps is a 20-watt solar panel?

Ans. Under ideal conditions, a 20-watt solar panel can produce around 1.34 amps of current per hour. You can calculate the amps by dividing the power in watts (W) by the voltage in volts (V).

Q4. Does a 20-watt solar panel need a controller?

Ans. Yes. Solar panel charge regulators are necessary because it’s unsafe to charge devices directly from the panels. The voltage fluctuates throughout the day. It can damage the battery and devices if used directly.

Q5. How many volts does a 20-watt solar panel produce?

Ans. In good sun, the panel produces about ~18 volts. With nothing connected, the output can be up to 22 volts.