How Much Solar Do I Need?

Solar energy is an amazing renewable power source that provides enough solar power for your residential usage. It saves your electricity bill. Solar panel absorbs energy from the sun, transferring the energy through a solar inverter and converting it into electricity. The amount of energy that solar panels can absorb, and then produce electricity, is measured in kilowatts (kW). The amount of energy your home uses over a certain timeframe is measured in kilowatt-hours (kWh). To calculate how much solar panel you’ll need for your home, you need to know the following: how much kWh’s energy your home uses the climate and peak sunlight in your area, your roof’s usable surface area, and determine the amount of kWs and relative efficiency of your photovoltaic (PV) panels you’re considering. This information is needed to find the correct system size and number of solar panels to power your house.

How Many Solar Panels Do You Need To Power Your Home

Your home size does not determine the number of solar panels you need. To determine how many solar panels your solar energy system needs, you have to consult a professional solar installer and determine the following solar evaluation.

How much solar power will you need?

To determine your home’s average energy requirements, you must look at past electricity bills. You can calculate how many solar panels you need by multiplying the hourly energy requirement of your home by the peak sunlight hours for your area and dividing that by a panel’s wattage.

How much amount of energy your home uses?

 Look at your electricity bill for average usage. Look for “Kilowatt Hour (or kWh) Used” for 30 days (1 month). If your bill doesn’t show kilowatt-hours used, look for beginning and ending meter readings and determine the monthly electric amount by subtracting the previous reading from the most recent one. If you want daily and hourly usage for your calculations and your bill doesn’t show a daily average, then you just divide the monthly or annual electricity bill by 30 or 365 days, respectively, and then divide again by 24 to determine your hourly average electricity usage. Your answer will be in kilowatt-hours (kWh). Your average daily energy usage is your target daily average to calculate your solar needs. That’s the number of kilowatt-hours you need your solar system to produce if you want to cover 100 percent of your energy needs. But it’s remembered that solar panels don’t operate at maximum efficiency at all times. Your system efficiency can temporarily reduce for weather conditions. So experts recommend adding a 25 percent buffer to your target daily average to ensure you can generate all the clean energy you need.

How Many Hours of Daily Sunlight Does Your Area Receive?

The peak sunlight hours for your particular location will have a direct impact on the energy you can expect your home solar system to produce. The “peak” sun hours vary from place to place. If you’re thinking about buying solar panels for your home, you are probably wondering whether or not you receive enough sunlight where you live. It’s not just the total amount of sunlight, but the ‘peak sun hours’ you get that is a primary criterion. Because solar panels produce electricity during all hours of the day, they work best when the sun’s rays shine directly on them. To calculate how many solar panels your solar energy system needs, we exactly determine how is the amount of direct sunlight affected by location and time of the year.

What affects solar panel output efficiency?

Not all solar panels are of the same quality. Solar panel efficiency means how well a panel can convert sunlight into energy. Solar panel efficiency depends on the quality of the panel. Not all solar panels are of the same quality. PV solar panels which are most commonly used in residential installations come in wattage ranging from about 150 watts to 370 watts per panel, depending on the panel size and efficiency and the cell technology.

The efficiency of a solar panel is measured through a simple method, the amount of electricity a solar panel can produce in watts divided by the amount of solar energy it absorbs from the sun. The standard testing conditions for solar panels assess how much electricity the panel can produce at a temperature of 25°C (77°F) with 1,000 watts of light per square meter hitting the device. That’s proportionate to a cool bright day with a solar panel tilted at 30° and facing south.

The most efficient solar cells made today which is more than 40 percent efficiency but those aren’t the solar cells or solar panels that you’re likely to have on your rooftop. Since they use exotic materials and usually end up powering satellites that need to maximize energy production in the smallest spaces, they’re incredibly expensive. The most efficient solar panels suitable for rooftops are now more than 20 percent efficient at converting sunlight into electricity.

Because of these wide variations in quality and efficiency, it’s difficult to make speculations about which solar panels are right for you or how many you’ll need for your home. The main point is that the more efficient the panels are, the more wattage they can produce, and the fewer you will need on your roof to get the same energy output. Conventional solar panels usually produce about 250 watts per panel, with varying levels of efficiency. In contrast, SunPower panels are known to be the most efficient solar panels on the market.

Topmost efficient solar panels amongst the 50 most commonly installed residential solar panels:

Sunpower X Series,  REC Solar, LG Solar, Canadian Solar, Panasonic HIT panels, Upsolar, JinkoSolar, Solaria, ReneSolar, Recom, Trina Solar, etc.

If you determine the kW size of the solar panel system, you need to select amongst the topmost solar panel and its efficiency that will take up on your roof. If you have extra space to spare, it might make sense to buy lower efficiency panels since they are cheaper than higher efficiency and can produce the same amount of electricity.

What is the effect of solar panel size?

If you have a small or unusually shaped roof, solar panel size and numbers are significant considerations. With a large usable rooftop area, maybe you can sacrifice some efficiency and buy larger panels at a lower cost per panel to get your target energy as output. In any case, if your usable roof area is constrained, or if it’s partially shaded, being able to use fewer smaller high-efficiency panels may be the best way to make the most possible power over the long-term and also saving you more money. Typical residential solar panel dimensions today are around 65 inches by 39 inches, or 5.4 feet by 3.25 feet, with some variation amongst manufacturers. SunPower panels are 61.3 inches by 41.2 inches.

These measurements have remained more or less unchanged for decades, but the efficiency and output from that same footprint have changed significantly for the better. SunPower designs entire systems to have virtually no gaps between panels and uses invisible framing and mounting equipment to keep the rooftop footprint as tight, efficient, and attractive as possible. The discussed factors will give you an idea of the ideal number of panels for your electricity generation needs — or at least a realistic range. Apart from that, a professional installer needs to assess your roof architecture, angle to the sun, and other factors to see if and how you’d be able to arrange the right number of panels on your rooftop to accomplish your daily energy production goals. You ought to likewise consider net metering as you’re considering figuring out your ROI for your solar system.

How do I find the exact amount of solar panels I need for my home?

The most ideal approach to decide the specific measure of solar panels your home needs is by working with solar installers. They will have the option to accurately calculate the type and amount of solar panels that will work best for your home. Solar panels are an incredible method to decrease or offset your electricity bill and take other money-saving advantages like net metering and federal incentives.

Key takeaways

  • More efficient solar panels mean less solar panels are needed
  • High-efficiency panels are necessary when installing solar panels on a small roof
  • If you live in a sunnier state, less solar panels are needed to generate the electricity your home needs
  • In Australia, a typical home uses 20kWh per day, which equates to a 5kW system. Your solar system might have 20 x 250W panels, or 25 x 200W panels; in either case, it’s a 5000W (5kW) system and that’s the number that matters.
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