How To Size Solar Panels For Home

Whats The Typical Power Output Of A Solar Panel

The typical wattage of a residential solar panel is around 300W, although you can find panels that exceed 400W if you really want your PV system to pack a punch.

Consequently, if you wanted to create a 1.2 kilowatt peak solar array, you would need four 300W panels . Similarly, eight 300W solar panels would create a 2.4kWp system. You get the idea.

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How To Use Pv

The previous section assumed that you can mount solar panels at an ideal location: Perfectly south facing, with a great tilt-angle, and without any shading. What if your roof, or other location, is not quite that good? In most cases we can still accurately figure out what it will take to produce the kWhs needed. All we need is a little help from the US tax payers!

The US government, and NREL in particular, has created a very handy online tool that can calculate solar PV yield for any place on earth, taking orientation, angle, and even the local weather patterns such as cloud cover into account. It is called PV-Watts and clicking this link should open it up in a separate window. First we enter the location of the solar panels, or Ottawa to stick with our previous example. PV-Watts now finds the nearest location that it has weather data for, and displays that. Go to the next screen, and for our example we need to change a few parameters. The DC system size is how much solar PV you have, in kW. We want to know what each kW of panels will produce so change this to 1. The module type of Standard should be fine for most, we can also leave Array type to the default of Fixed . The system losses of 14.08% are fine too. For the Tilt we will change this to 45 degrees, the latitude of Ottawa, just like our earlier example, and the Azimuth is fine at 180 degrees .

Correction factor = PV-Watts reported yield per kW of panels / Actual yield per kW of panels

Preserve Peace Of Mind

Rooftop solar panels with battery storage generate electricity and provide a backup power solution. During an outage, Brightbox keeps preferred circuits powered. Our energy storage system enables you to run four 15-20 Amp, 120V circuit breakers for approximately 8 to 12 hoursenough to keep essentials humming until the sun rises.

Solar cant change the weather. But, having electricity during an outage gives you peace of mind and a value beyond money.

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Final Thoughts From Koos Mulder

To conclude this article, weve reached out to an expert in solar off-grid systems, Koos Mulder. Koos is installing micro-grid systems in remote villages throughout the Philippines for the Shell Foundation.

According to Koos:

Microinverters can be a good choice for AC coupled systems thanks to their high efficiency, however, he brought attention to two issues:

• Safety As the back of a solar panel can be very hot and the more inverters you have the higher the risk of an electric fire
• Maintenance Although you might not need to perform maintenance for years, when you eventually do, it might be complicated to figure out where the defective micro-inverter is.

He still favors central hybrids inverters as they are much easier to install, control and ultimately, they are cheaper. They might be slightly less efficient but it is balanced by all the previous advantages.

In the end, the main trend is now geared towards energy storage at home, with smart inverters and solar batteries: the Energy Storage Systems .

Electricity consumers will turn into prosumers, to sell their excess electricity to the grid when prices are high.

By doing this, we could achieve a higher amount of renewable energies in our global electricity production.

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Few Things About Solar Panel Output Efficiency

Solar panel type and quality make a significant difference in terms of solar output and efficiency. Not all solar panels are the same.

For instance, monocrystalline photovoltaic solar panels are known to be the most efficient solar panels on the market, but also the most expensive.

Their two main advantages over the other types of solar panels such as polycrystalline or thin film panels is that 1) they absorb more sunlight than conventional cells and their output efficiency is not affected that much by temperature and 2) they occupy less space. These are an ideal option if you do not have enough roof space for standard panels.

On the other hand, polycrystalline panels are cheaper, they are less efficient and therefore occupy more space, but offer a better return on investment than monocrystalline panels.

Because of these wide differences in quality and efficiency, its up to you to decide which solar panels are right for your home.

The main takeaway is that, the more efficient the panels are, the more power they can produce, and the fewer photovoltaic panels you will need on your roof to get the same energy output as you would get with polycrystalline or thin film solar panels.

Overall, if money is not an issue, monocrystalline panels are the best option.

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How Many Hours Of Sunlight Can You Expect In Your Area

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. For example, if you live in Phoenix you can expect to have a greater number of peak sunlight hours than if you lived in Seattle. That doesnt mean a Seattle homeowner cant go solar it just means the homeowner would need more panels.

The Renewable Resource Data Center provides sunlight information by state and for major cities.

Now multiply your hourly usage by 1,000 to convert your hourly power generation need to watts. Divide your average hourly wattage requirement by the number of daily peak sunlight hours for your area. This gives you the amount of energy your panels need to produce every hour. So the average U.S. home in an area that gets five peak sunlight hours per day would need 6,000 watts.

The Final Calculation Of The Size Of The Solar Power System Needed

Once the daily power requirement estimation has been done, we need to check those calculations for each season. For instance, say the figure applicable to daily power requirement we arrived at is 240w.

We divide the daily watts required by the number of sunshine hours for the season to get the panel size .

• 240 watt-hours/ 6 h = 40 Watt panel.

Similarly the calculation for winter daylight hours gives:

• 240watt-hours / 4h= 60 Watt panel.

Depending on the brand of solar panel that you choose to buy, you will know the size of the solar panel you need. So if your chosen company makes 30 watt panels, then you need two panels connected in series. Note that based on the above calculations, the most satisfactory requirement for all year would be to use the higher number of watts and thus solar panels.

The above factors and metrics will help you in calculating the energy requirements for the solar power system that needs to be set up. There may be a difference in the estimated numbers from the actual watts output delivered. When the system is up and functioning you can adjust it.

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Do Solar Panels Increase The Value Of Your Home

Solar panels can increase the value of your home as they make your house more energy-efficient. This is one of the home improvements that make your home more attractive to potential buyers, as the new owners can enjoy the same benefits of reduced electricity bills.

Naturally, the size of the solar panel system will affect just how much the value will increase, and bear in mind that different families will have different energy expenditure habits. That means that one system may be adequate for some families and inadequate for others.

For some buyers, solar panels are not a valuable addition to a home, so it does depend on personal preference.

Get Free And Instant Quotes From Installers In Your Area

We hope the above points are helpful to you. Take 30 seconds to complete our Solar Quote Comparison Request form, or feel free to give your Solar Choice broker a call on 1300 78 72 73 to further discuss what size installation best suits your budget and energy needs. Our service is 100% free to our residential customers.

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Why Does The Biggest System Not Have The Largest Savings

There may be days throughout the year where you consume more energy than your solar system produces, and days where you consume less. Many electric utilities add up all the excess energy that you generate during the year, and subtract it from your total energy consumption during that year. You only have to pay the difference. This is called net metering.

Some utilities will not give you full credit for generating electricity beyond what you consumed that year. Therefore, to maximize your savings, you want to base your system size on your expected electricity usage, without generating a lot of net excess over the year that you cant use.

Our recommended system size on your order is based on offsetting your current energy usage, determined by the average electric bill that you enter. If you plan to add an electric vehicle or other electric appliances in the future, you may want to consider getting a larger system size.

Frequently Asked Questions About Solar Panel Size

What is a standard solar panel size?

A residential solar panel is typically around 5.5 feet long and just over 3 feet wide. Commercial solar panels, on the other hand, are typically 78 by 39 inches.

How big is a 300W solar panel?

Many residential solar panels, which are around 5.5 feet long and 3 feet wide, are rated for 300W per panel. The actual power produced by a panel varies depending on a few factors, such as geographical location and the tilt of the panels.

What is the best size of solar panels?

This depends largely on the space you have available. Large panels are more suitable for commercial installations, houses with large roofs, or any other area with a lot of open space. On the other hand, small solar panels are best if you have a small or otherwise complicated rooftop.

How big is a 500W solar panel?

In the past, the rule of thumb with solar panels was that a bigger size equaled higher wattage. Recently, however, many manufacturers have increased their efficiency, meaning there isnt a hard and fast rule regarding size. Read our article about 500W solar panels to learn more.

Are there multiple sizes of solar panels?

Solar panels vary in size, largely based on project type i.e., commercial or residential. However, solar panels are typically built with either 60 or 72 cells, the two most common configurations. There are smaller sizes though, such as 100W solar panels for RVs, that are designed to fit in a smaller area or be used on the go.

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Are You Buying A Solar Panel For Your Rooftop

Lets understand what is meant by Rooftop Photovoltaic Power Station, or Rooftop PV System its a photovoltaic system that has its electricity-generating Solar Panels mounted on the rooftop of a residential or commercial building or structure.One of the crucial first steps to consider is Solar Sizing.

Doing a proper solar PV system sizing would help you answer questions like:

• How much should be the Solar PV capacity?
• What Solar Panel size to buy?
• How much should be the Inverter/ Battery size?

Not doing a proper Solar PV sizing can result in not installing the right kind of Solar PV system.

In this article we look at all the critical elements when sizing a Solar PV system.

Interested to know more?

Lets dive in.

What Are The Most Reputable Solar Panel Manufacturers

Since the upswing of the use of renewable energy, there has been an increase in solar panel manufacturers on the global market. At GreenMatch, we work with both industry veterans that have been producing photovoltaic modules since the 1960s and new players on the market that are making strides in solar energy technology.

Here is a breakdown of the top 12 solar panel manufacturers currently on the market:

Fill in the form in just 1 minute

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Understanding Your Electricity Usage

You can’t correctly size your solar PV system unless you know how much electricity your home uses now . The easiest way to figure this out is to look at past electricity bills, which should tell you how much power you’ve used in the previous month or quarter. From this you can figure out the average daily usage. This is even easier if you have a smart meter installed you should be able to see your daily usage either on the bill or by checking your account online.

Your power consumption is measured and billed in kilowatt-hours .

A typical Australian home uses 1520kWh per day. But households can vary considerably in their electricity consumption, depending on the number of people living there, the area they live in, whether they use gas for cooking or hot water, and many other factors. For example, a single-person home will typically use about 812kWh per day on average, while a household of five people with a pool could use 3040kWh per day.

Time of day and seasonal usage

It’s important to consider when you use electricity. Is your home generally empty during weekdays, with everyone at work or school, so that your main power consumption comes in the evening? If so, your solar panels might not be used most effectively, as it’s better to use the generated power during the day than export it to the grid.

Also consider whether some days are more power-hungry that others the weekend for instance, when everyone is at home. And do you use more power in summer or in winter ?

Energy Usage = How Much You Need

We always start with energy usage when sizing a solar system. For existing homes we prefer to look at your previous 12 months of electric bills so we can establish a good sense of your energy usage patterns over the course of a year. If we arent able to get a full 12 month view of your bills, we can estimate your monthly usage based on your peak winter and peak summer usage while factoring in whether you use natural gas or electricity for heating.

For new construction homes, our building science team can create an energy model for your home that predicts your future energy usage .

Once we have a sense of your electricity consumption needs, well talk with you about any events on the horizon that might impact your usage. Are you thinking about getting an electric vehicle? Are your kids moving out soon? Are you going to get a pool with your end of year bonus? Are you contemplating mining Bitcoin or starting a hydroponic farm? Well take all of these changes into account to appropriately size your system up or down.

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How To Calculate The Number Of Solar Panels You Need

Our calculator below is the fastest, easiest, and most accurate way to find out how many solar panels your home needs – and you dont have to do any math.

Our solar panel cost and savings calculator is the fastest, easiest, and most accurate way to find out how many solar panels your home needs – and you dont have to do any math. Plus, well give you the average cost of a solar installation for your specific home and how much itll save you on your electric bills.

However, if you want to put pen to paper and work out the calculations for yourself, follow these four easy steps to find how many solar panels you need.

How To Prevent Inverter Clipping

While oversizing the solar array relative to the inverters rating can help your system capture more energy throughout the day, this approach is not without costs.

Either spend money on an additional inverter or lose energy harvest to inverter clipping.

What Figure 1 also shows is an effect called inverter clipping, sometimes referred to as power limiting. When the DC maximum power point of the solar array or the point at which the solar array is generating the most amount of energy is greater than the inverters power rating, the extra power generated by the array is clipped by the inverter to ensure its operating within its capabilities.

The inverter effectively prevents the system from reaching its MPP, capping the power at the inverters nameplate power rating.

To prevent this, its crucial to model inverter clipping to design a system with a DC-to-AC ratio greater than 1, especially in regions that frequently see an irradiance larger than the standard test conditions irradiance of 1000 W/m2 .

The US Energy and Information Administration states, for individual systems, inverter loading ratios are usually between 1.13 and 1.30.

Knowing how much energy is clipped allows a designer to understand how effective the oversizing scheme is at increasing energy harvest, and ultimately determine what system configuration is the most cost-effective.

The chart below shows three DC-to-AC ratios and their estimated losses to clipping.

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