Solar PV Panel Calculator: How Many Panels Do I Need?

☀️ Solar PV Panel Calculator

Estimate how many solar panels you need based on your energy usage, location, and panel type

Quick Presets
☀️ Your Solar System Estimate
📊 Panel Type Comparison
400W
Monocrystalline
20% efficiency
320W
Polycrystalline
16% efficiency
440W
PERC Mono
22% efficiency
450W
Bifacial
22.5% efficiency
480W
HJT Panel
24% efficiency
460W
TOPCon
23% efficiency
250W
Thin Film
11% efficiency
17.5
Sq Ft / Panel
standard 400W panel
🗺 Peak Sun Hours by Region
Region / City Peak Sun Hrs/Day Annual kWh/kW Rating
Phoenix, AZ6.5 hrs~2,300 kWhExcellent
Las Vegas, NV6.3 hrs~2,200 kWhExcellent
Los Angeles, CA5.6 hrs~1,950 kWhVery High
Denver, CO5.5 hrs~1,900 kWhHigh
Miami, FL5.3 hrs~1,850 kWhHigh
Dallas, TX5.2 hrs~1,800 kWhHigh
New York, NY4.4 hrs~1,500 kWhAverage
Chicago, IL4.2 hrs~1,450 kWhAverage
Seattle, WA3.5 hrs~1,100 kWhBelow Avg
London, UK3.0 hrs~950 kWhLow
📋 System Size vs. Home Usage
Monthly Usage System Size (kW) Panels Needed (400W) Roof Area Needed
300 kWh / mo~2.5 kW6–7 panels~120 sq ft
500 kWh / mo~4.0 kW10 panels~175 sq ft
750 kWh / mo~6.0 kW15 panels~263 sq ft
900 kWh / mo~7.5 kW19 panels~333 sq ft
1,200 kWh / mo~10.0 kW25 panels~438 sq ft
1,500 kWh / mo~12.5 kW32 panels~560 sq ft
2,000 kWh / mo~16.5 kW42 panels~735 sq ft
🔌 Common Home Appliance Energy Use
Appliance Watts Hrs/Day Avg kWh/Month
Central Air Conditioner3,500W6 hrs~630 kWh
Electric Water Heater4,500W3 hrs~405 kWh
Electric Vehicle Charger (L2)7,200W2 hrs~432 kWh
Refrigerator150W24 hrs~108 kWh
Clothes Dryer5,000W1 hr~150 kWh
Pool Pump1,500W8 hrs~360 kWh
LED Lighting (home)200W5 hrs~30 kWh
TV + Entertainment250W5 hrs~37 kWh
✔ Tip 1 — Read Your Utility Bill: Find your average monthly kWh usage on your electricity bill. Use a 12-month average for the most accurate solar sizing — seasonal usage varies significantly due to heating and cooling loads.
✔ Tip 2 — The 80% Derate Rule: Real-world solar output is always less than nameplate (rated) wattage due to inverter losses, wiring resistance, temperature effects, and dust. Always apply a derate factor of 75–85% to your calculations for accurate sizing.

solar pv panel are devices that seize energy from the sun and turn it into pure electricity. One also calls them solar pv panel. Typical solar pv panel are made up of several cells done from layers of special material, usually silicon.

When sunshine hits that material it creates flow of electricity.

What Are Solar PV Panels

The most common solar pv panel use crystalline silicon, that one finds easily and that works well. It comes in single crystal or polycrystalline form. Layers of glass and protective plastic materials surround the silicon, so that it lasts long term and resists the weather.

Aluminum frames give the panel its shape and strength.

One calls a whole solar energy setup a solar pv panel system. It has some parts that are involved. The solar pv panel themselves absorb the sunlight and convert it into electricity.

Later comes the solar inverter, that converts the direct electricity into alternating. Also, one needs batteries, cables and other electrical parts, so that the whole thing works. Basically, a solar system is a gruop of panels connected to reach the wanted output.

The efficiency of solar pv panel usually falls between 15 and 20 percent. It really matters only when the available space is limited. A 300-watt panel stays a 300-watt panel, but a more efficient model will be physically smaller than a less efficient one.

Modern solar pv panel average around 400 watts each unit, and that is the maximum production under perfectly clear sky at midday with a new panel.

Many folks believe that solar pv panel stop working after 25 years, but that is not really true. Research showed that setups from the 1980s still give more then 80 percent of their original ability. Choosing a known brand from a tier-1 producer helps to have a system that lasts 30 years or even more.

Solar pv panel installers are the specialists that assemble, mount and take care of those systems. The most common jobs happen outside on roofs, although sometimes one works in attic or crawl spaces to bind panels to the grid.

The price of solar gear, including supplies and tax, reaches around 14 055 dollars, what is about 46 percent of the whole system price. It ranges based on the chosen brand and quality. Investing in great gear can lead to bigger long term savings, but choosing the most expensive panels is not always the best idea.

The main downside of solar energy is the starting cost, although panels now cost much less than 20 years ago. Hybrid solar system, that is grid-tied solar pv panel with battery storage, becomesalways more liked.

Solar PV Panel Calculator: How Many Panels Do I Need?

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