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Solar Panel Wattage Calculator

Created by Rahul Dhari and Rangsimatiti Binda Saichompoo
Reviewed by Mariamy Chrdileli and Adena Benn
Last updated: Feb 28, 2024

This solar panel wattage calculator allows you to calculate the cost of your solar energy according to the energy consumption of your household appliances. If you want to know more about solar power and the panel size, feel free to explore our fun and helpful solar panel calculator.☀️

Are you ready to find out how much solar energy and cost your house needs? Let's go!

Solar panel sizes and wattage

There are three main solar panel sizes: 60-cell, 72-cell, and 96-cell. 60-cell and 72-cell solar panels are more common since their size is more practical for households.

Solar panel sizes

Apart from size, various types of solar panels are characterized by energy output in Watts (W). Solar cells' efficiency in converting sunlight into electricity depends on these wattage ratings. The most well-known type is 400 W solar panels, which produce an energy range of 1.2-3 kWh. The higher the wattage, the better energy production efficiency your solar panels will have!

These solar panels can range between 400-600 dollars, depending on size, wattage, and solar panel producers in your country. Are you planning to compare the current electricity cost of your house to see whether it's worth shifting to solar power? You're in the right place! This solar panel wattage calculator will help you.

🙋 If you are interested in other clean energies⚡️, check out our wind turbine calculator and the hydroelectric power calculator!

Household energy consumption

How is total energy consumption determined? Well, the real question is "What kind of devices do you have in your house?" ☎️📠💻

Have a look at the table below to see an approximated energy consumption from different household appliances per hour. You can also choose these appliances in this solar panel wattage calculator!

Household applliances

Energy consumption (W/hour)

Household applliances

Energy consumption (W/hour)


180 W

Internet router

6 W

Coffee machine

800 W

Clothes dryer

3,000 W


1,200 W

Clothes washer

500 W


1,800 W

Hair dryer

1,500 W


1,200 W

Air conditioning

3,500 W


1,500 W


1,500 W


2,400 W

Vacuum cleaner

1,400 W

Solar panel wattage calculator — How to calculate total solar energy and cost?

As an example, let's say that your solar panel is connected to appliances in your kitchen. You want to know how much solar energy is needed in total to keep your kitchen functioning with solar energy per month and its cost.

In the kitchen, you have each of the following devices:

  • Three 8 W LED light bulbs used 3 h/day,
  • Fridge of 180 W used 24 h/day,
  • Coffee machine of 800 W used 15 min/day,
  • Stove of 1,500 W used 1 h/day, and
  • Dishwasher of 1,800 W used 1 h/day.
Example of household appliances powered by solar panels.
  1. Calculate the total energy used per day for each device with the equation:
Total energydevice=W× n ×t\medspace\medspace\medspace\footnotesize\text{Total energy}_\text{device} = \text{W} \times\ \text{n}\ \times \text{t}

W\text{W} – Power rating of device in watts,
n\text{n} – Number of devices,
t\text{t} – Running time in hours.

Total energyLED bulbs=8× 3 ×3=72 WTotal energyfridge=180× 1 ×24=4,320 WTotal energycoffee machine=800× 1 ×0.25=200 WTotal energystove=1,500× 1 ×1=1,500 WTotal energydishwasher=1,800× 1 ×1=1,800 W\begin{split} \footnotesize\text{Total energy}_\text{LED bulbs} &= \footnotesize\text{8} \times\ \text{3}\ \times \text{3} = \footnotesize72\ \text{W}\\ \footnotesize\text{Total energy}_\text{fridge} &= \footnotesize\text{180} \times\ \text{1}\ \times \text{24} = \footnotesize4,\!320\ \text{W}\\ \footnotesize\text{Total energy}_\text{coffee machine} &= \footnotesize\text{800} \times\ \text{1}\ \times \text{0.25} = \footnotesize200\ \text{W}\\ \footnotesize\text{Total energy}_\text{stove} &= \footnotesize1,\!500\times\ \text{1}\ \times \text{1} = \footnotesize1,\!500\ \text{W}\\ \footnotesize\text{Total energy}_\text{dishwasher} &= \footnotesize1,\!800\times\ \text{1}\ \times \text{1} = \footnotesize1,\!800\ \text{W}\\ \end{split}
  1. Sum the total energy used per day from each device:
Total energykitchen=72 W+4,320 W+200 W+1,500 W+1,800 W=7,892 W or 7.892 kW\begin{split} \footnotesize\text{Total energy}_\text{kitchen} &= \footnotesize72\ \text{W} + 4,\!320\ \text{W} + 200\ \text{W} + 1,\!500\ \text{W} + 1,\!800\ \text{W}\\ &= \footnotesize7,\!892\ \text{W}\ \text{or}\ 7.892\ \text{kW} \end{split}

🙋 You might find this watt converter useful to convert watts (W) into kilowatts (kW).

  1. Multiply the total energy obtained by 30 days to find out how much total energy your kitchen will need per month:
Monthly total energykitchen=7.892×30 days=236.76 kWh\begin{split} \footnotesize\text{Monthly total energy}_\text{kitchen} &= \footnotesize7.892\times30\ \text{days}\\&=236.76\ \text{kWh} \end{split}
  1. To find the cost of your solar energy per month, multiply your monthly total energy by the unit cost. In this case, $0.12 kWh:
Monthly costsolar energy=236.76 kWh×0.12 $=28.41 $\begin{split} \footnotesize\text{Monthly cost}_\text{solar energy} &= \footnotesize236.76\ \text{kWh}\times0.12\ \$\\&=28.41\ \$ \end{split}

What to consider before getting solar panels?

If you are planning to purchase solar panels to power your house, here are a few things to consider:

  • Solar panel size – The more surface area it has to receive sunlight, the more energy it can produce.

  • Solar panel efficiency – Monocrystalline panels have the highest efficiency compared to polycrystalline and thin-film panels. However, they come with a higher cost.

  • Solar hours and climate of your location – The amount of sunlight is your energy source. Solar panels might not be worth it if you live somewhere with little sunlight.

  • Roof size available for solar panels – How many solar panels can fit on your roof? Will they produce enough energy for your house?

  • Angle of the setting and the roof – The optimal angle for solar panels is between 30 and 45 degrees.

  • Energy consumption of your household – Find the total energy consumption from your electricity bills, and find out what kind of solar panel is the most suitable for you.

  • The cost of solar panels and long-term savings – Normally, solar panels should help you save electricity bills in the long run. Use our solar panel wattage calculator to find out!


How much power does a 400 W solar panel produce?

A 400 W solar panel can produce around 1.2-3 kWh or 1,200-3,000 Wh of direct current (DC). The power produced by solar panels can vary depending on the size and number of your solar panels, the efficiency of solar panels, and the climate in your area.

How many solar panels are needed to run a house?

On average, 15-20 solar panels of 400 W are needed to power a house. This can vary depending on your solar panels' wattage rating, solar panels' efficiency, and the climate in your area.

How do I calculate my electricity consumption?

To calculate the electricity consumption of your house or office, follow these simple steps:

  1. List your devices or appliances that consume electricity.
  2. Find out the energy consumption per hour of each device — let's say 40 W for TV, 6 W for router, 1,000 W for AC, and 8 W for each light bulb.
  3. Approximate the number of hours the device is used — multiply the hours by the wattage of each appliance.
  4. Sum up the energy consumption for each appliance:

Total consumption = (40 × 2)+(6 × 24)+(1,000 × 2)+(8 × 2 × 4) = 80 + 144 + 2,000 + 64 = 2,288 W

  1. That's it! Now you have your total electricity consumption.

How much do solar panels cost?

The average cost of a 400 W solar panel can range from 400-600 dollars, depending on various factors. Most of the time, up to 15-20 panels are needed to power a house completely. The table below shows the average costs of each system size:

System size

Average annual output (kWh)

Average cost before tax credit

Average cost after tax credit (30%)

6 Kw

8,000 - 10,000

$6,600 - $11,400

$4,600 - $8,000

8 Kw

10,500 - 13,300

$8,800 - $15,200

$6,200 - $10,600

10 Kw

13,300 - 16,700

$11,000 - $19,000

$7,700 - $13,300

12 Kw

16,000 - 20,000

$13,200 - $22,800

$9,200 - $16,000

What can affect my solar panel wattage?

Here are several things that could affect the solar energy output of your solar panels:

  • Size, type, and photovoltaic efficiency of solar panels.
  • Solar hours and climate of your location.
  • Average roof size available for solar panels.
  • Angle of the roof and solar panel setting.
  • Energy consumption of your household.
Rahul Dhari and Rangsimatiti Binda Saichompoo
Use this calculator to estimate your household electricity consumption. If you are looking for a simplified version, please use this electricity cost calculator. You can begin by adding the appliances you own. After adding the appliances in the calculator, if you wish to exclude a specific one from the energy consumption cost, simply click Remove and select the desired appliance.
Energy consumption (monthly)
Unit cost
$ /
Monthly cost (without taxes)
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