Thursday, March 16, 2023

How To Calculate Savings From Solar Panels

You Need To Know How Much You Pay On Your Electric Bill

How To Use Solar Savings Calculator

This estimate assumes you will get all of your power from solar. While some homes will be able to get 100% of their electricity from solar, or even sell some surplus energy back to the grid, others will still have an electric bill to supplement usage. This will vary widely from home to home, depending on how many solar panels are installed, normal energy consumption and more. Get more tools to calculate your home’s potential savings here.

Now you have a sense of how much energy you’ll save, login to your electric utility company account and calculate an average of your last several electricity bills. Go back at least six months, if possible, to account for seasonal temperature changes and other fluctuations in cost. Let’s assume you get 100% of your usage from the panels and currently pay an average of $125 per month in electricity bills, or $1,500 per year. Now you have the information you need to estimate the payback period for solar panels.

How To Use This Calculator

At a minimum, simply enter your postcode and the solar system size you are considering into the calculator. Then enter your typical annual electricity bill .

You can leave all the other inputs as their default values and hit ‘calculate’.

The calculator will provide a good estimate of your bills if you had that solar power system, along with the payback. You may be surprised at how low your bills can be with solar panels alone.

Next, experiment with different solar system sizes, and see if bigger is better for you. It usually is.

Then add a battery to the calculator to see how that affects your bills and the marginal payback of adding energy storage. Again, you may be surprised at how little a battery saves you compared to the solar panels although it will depend on how generous your feed-in-tariff is.

View further information and a video on how to use this calculator here.

What Is Googles Project Sunroof

Google has dabbled in the solar market with Project Sunroof since August 2015. Project Sunroof uses Google Earths high-resolution imagery to help calculate a roofs solar energy potential.

Upon entering an address, the tool analyzes factors such as shade, roof orientation, and local weather patterns to calculate how many hours of sunlight hit that roof in a typical year.

The findings are analyzed to create an estimate of how much power a user could produce, and how much cost savings are associated by going solar.

Read Also: How To Set Up Solar Panels For Your Home

Solar Roi Payback Calculator

Cost of electricity can be obtained from your utility provider. State-by-state averages can be found here.

Your electricity usage is printed on your electric bill. Take your monthly usage and multiply by 12 months, or gather a full years worth of bills from your utility for a more accurate estimate.

Do You Still Have An Electric Bill With Solar Panels

How to Count Your Home Solar Savings in 6 Steps

A common misconception about installing solar panels is that your electric bill will go away entirely. Even if you install enough solar to completely offset your electricity use, you will still receive an electric bill from your utility as long as your property remains grid-connected. However, this doesnt mean you will always be paying money on your bill heres why:

Thanks to a policy called net metering, which is available in most states, renewable energy your solar panels produce that you dont use immediately is sent to the grid in exchange for credits on your electric bill. This allows you to draw energy from the grid during the night but not pay any extra money, as long as you draw back the same amount or less than you provided to the grid. When you receive your monthly electric bill, any net metering credits you used that month will be indicated and you wont be charged for that power. The remaining electricity you pulled from the grid that wasnt offset by net metering credits and wasnt produced and used immediately at your home is where you might see small charges for electricity.

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How Many Solar Panels Do You Need To Power Your House

Example Sizing solar panel PV systems

How many solar panels and their power rating would be needed for a fixed solar system to cover the energy consumption of an average U.S. home?

Lets say the house is in Burns, Oregon USA, with an average electricity consumption per day of 33 kWh.

Checking the site Global Solar Atlas, we see that the irradiation in this location is 5.83kWh/m2/day.

Use historical irradiance data to find suns energy in your location

  • Geographic Location: Burns, Oregon, USA
  • Average daily energy consumption: 33kWh/day
  • Irradiation for Burns, Oregon is 5.83kWh/m2 per day

PV System Losses

I previously said that system losses can be 23%, but they can also be higher. Ill use 30% as the overall system loss, to make sure I dont underestimate the number of solar panels to cover the homes energy needs.

With 30% losses in mind, the energy needs are:

33kWh/day x 1.44 = 47.5 kWh/day load.

Now to take into account the efficiency of inverter, which is about 96%.

The power to be supplied to the inverter = 47.5/0.96 = 49.5kWh/day.

The average daily irradiation is 5.83kWh/m2

49.5kWh/day of power can be produced by:

49.5/5.83kWh/m2= 8.5kW or 9kW of solar panels working at 100% capacity rating.

To find the number of solar panels needed, divide the wattage needed by wattage of each solar panel :

Number of panels needed = 9kW/300 watts per panel = 30 solar panels.

Final Word On Solar Panel Payback Period

Now that youve read through the steps outlined in this article, you can calculate the estimated solar payback period if youve gotten a quote for home solar panels. If you havent yet received solar panel quotes, you can start the process by using our solar panel calculator and learning about offers from solar providers in your area.

Remember, the method above just results in a simple payback estimate, without accounting for increases in electricity costs over time, solar panel degradation, or any other factors.

In addition to electric bill savings, there are other benefits of solar panels which arent as easy to put a value on. The most important of these is an increase in home value, estimated to be about 4% of the pre-solar value of your home.

On top of that, there are environmental benefits of renewable energy and, if you add batteries to your solar installation, the peace of mind that comes with being more resilient if the power goes out.

Adding solar panels to your home truly does add value in many ways.

See how much you can save with solar panels for your home

Read Also: What’s The Best Type Of Solar Panel

Calculate The Solar Energy System Payback Period

The last step in figuring when your PV system will begin to pay off in profits involves a bit more math.

Take your total photovoltaic installation cost and divide by your annual energy savings to calculate the number of years for solar payback. Using our example:

$9,000 ÷ $1,368 = 6.58 years

Or for a system sized to provide 80 percent of the home energy consumption:

$9,000 ÷ $1094.40 = 8.22 years

Keep in mind, however, that everyone has a different set of data. Several factors including the solar radiation in your location and the exact energy output from your photovoltaic panels can affect your PV payback period.

The best way to find out the return you can expect on a photovoltaic investment is to consult with a local expert. Intermountain Wind & Solar, the regions leading photovoltaic professionals, offers free consultations to home and business owners throughout Utah, Idaho, Nevada, Colorado and Wyoming.

For answers to all your questions about installing a solar energy system, contact us today.

How To Calculate Solar Panel System Size

How To Calculate Savings From Off Grid Solar Power System

Solar panel sizing starts with the load to be supplied. In the case of a home, then the annual, monthly or daily kilowatt-hours can be used.

The fastest and easiest way to get this is to take it from last years utility bill.

Once you have the homes kWh, then it can be translated into solar panel generated energy, system rated watts and work out how many panels are needed.

Read Also: How To Get Certified In Solar Panel Installation

How Do I Calculate Solar Panels For My Home

Once you have found your daily energy consumption, it can be used to size your solar panels.

It needs to be said that solar panel power ratings are not an accurate reflection of the actual power generation in real-life conditions.

In fact, there are many losses associated with a working home solar system. As much as 23% is normally lost and must be deducted from the solar array power rating see infographic below:

Infographic showing solar panel losses solar calculations must consider losses

The calculator I provide later on in the post takes these losses into account, but for this example Ill go through the process manually step-by-step.

Will A 5kw Solar System Run A House

You need to know how many kilowatt hours of energy your house uses per day/month or year.

Using the American home average of 30kWh/day and system loss factor of 1.44, we can work out how much energy a 5kW solar system could generate.

Applying the PV system loss adjustment factor of 1.44, you would need to generate:

30kWh x 1.44 = 43.2 kWh of solar energy

With an average of 4 peak-sun-hours 1 solar watt can generate 4 watt-hours/day. Therefore, the solar power needed to supply this home is:

43200/4 = 10.8kW

A 5kWh solar system would not run the average US home with energy consumption of 30kWh/day. More than double this amount would be needed at 10.8kWh if the total energy requirements were to be generated from solar.

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How Do I Calculate Solar Panel Return On Investment

The other figure youre probably interested in is how much money you stand to save over the life of your system.

For that, we want to calculate the cost of ownership over the life of your panel warranty , and compare it to the cost of buying electricity from the utility company over that same time period.

Also note that inverters have shorter lifespans than solar panels. Youll need to replace your inverter at least once over the systems lifetime, which should be factored in to your ROI calculations.

At its simplest, heres how to calculate your return on investment into solar:

Lifetime cost of electricity from utility lifetime cost of solar = Solar ROI

The lifetime cost of solar includes:

  • Equipment

And heres how to calculate lifetime cost of electricity:

Cost of electricity per kWh x Monthly kWh usage x 12 months x 25 years

Cost Of Electricity And Rate Of Increase In That Cost

Calculate exactly how much money you can save by using # ...

Heres where the rubber meets the road. In a state with net metering, you can take the number of kWh your system will produce in a year and multiply it by your per-kWh rate from the utility. That number will equal your annual solar savings.

To get a simple solar payback time frame, just divide the net cost from Step 3 by your average annual savings to get the number of years it will take for your solar savings to equal the net cost of the system.

Unfortunately, however, its not always that easy. Why? Because electricity rates increase over time, and some states do not offer net metering.

Example 5:

Heres where our friend in Bakersfield finally learns their solar payback period!

Californias net metering law is a bit complicated, and your average rate depends on time-of-use billing. Click on those links to learn more, but for our purposes well use an average cost per-kWh here.

The solar energy our friends panels make earns them an average of 24 cents per kWh. Therefore, those 10,200 kWh will save them an estimated $2,450 in one year. Dividing $12,654 by $2,450 gives a solar payback period of about 5.2 years, even if electric rates dont go up between now and then.

If their solar panels were fully connected by September 2021, theyd be paid off before the summer of 2027, and will keep making electricity until at least 2047. Thats what wed call a great deal!

Electricity rates increase over time
Some states dont offer net metering

Read Also: Why Are Solar Panels Good

Figure Out Your Yearly Electricity Savings

Before installing your solar energy system, how much did you spend on electricity each year?

Total the amounts of your electricity bills for the last 12 months to get your yearly total. Most homeowners pay just over $114 per month, according to the U.S. Energy Information Administration. So for our example, well use the national average thats a total of $1,368 for the year.

Of course, your actual energy savings will depend upon the percentage of your homes electricity your solar array provides. For instance, if yours is sized to cover 80 percent of your energy consumption, your savings will be 80 percent of your yearly total. Using our example:

$1,368 × 0.80 = $1,094.40

To determine your annual savings, plug your own numbers for energy costs and generation capacity into the equation.

How To Calculate Home Energy Consumption

You could add up the wattage of all your appliances and estimate how many hours they are used each day, but this is very cumbersome and not accurate.

For example, some appliances, such as refrigerators, are difficult to estimate. This is because they have compressor motors on board and have variable instantaneous power values.

By far the easiest way is to take it from last years utility bill, which normally shows the full years energy consumption in kilowatt-hours .

Simply divide this figure by 12 to get the monthy consumption, or 365 for the average daily consumption.

The average amnount in the US is about 30kW per day, but your own will depend on where you live.

Also Check: What Is The Average Cost Of A Home Solar System

How Much Can Solar Energy Save You

As an electrician and solar installer, many people ask me How much can I save with solar? Is it really worth it? How long will it take to recover the money invested?

It is evident that more and more people are making the switch to solar, and that is because solar is a great option to save money and obtain energy from an inexhaustible source -the sun.

The Solar Savings Calculator below will help you get an idea of what you can save with solar, depending on your current consumption, and the size of the solar panels you want to put on your roof.

Once you have set the requested parameters, you will be able to find out your:

  • Estimated Annual Self-Consumption Savings
  • Estimated Annual Feed-in Savings
  • Estimated Total Annual Savings

If you are not sure about some of the steps from the Solar Savings Calculator, you can check the information below. Please bear in mind that these numbers are indicative and that each situation needs to be evaluated individually by solar experts.

Why Use A Solar Calculator

Calculating your Solar Savings- How To – Video 2

The solar calculator on has been recently upgraded in order to provide customers with the most accurate instant assessment of potential savings associated with going solar .

Our solar energy savings calculator helps you discover:

  • What would be my estimated electricity bill after going solar?
  • What are my electricity savings after installing a solar panel system?
  • What should be the size of my system?
  • What panels make sense for my roof?
  • What are the different government incentives Im eligible for?

In short, we help you Discover Your Solar Potential!

Our solar savings calculator provides accurate cost and savings estimates by analyzing your current electricity bill, rooftop, and the solar pricing in your area.

Solar.coms solar calculator is the first-ever to deploy Googles Project Sunroof API to instantly deliver solar estimates on a roof-by-roof basis.

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Your Potential Savings Per Annum

Household type gives an indication of the percentage of the solar energy generated that you consume. This ensures a significantly more accurate solar calculation. Always ensure generation figures quoted match your region.

The charge rate is the amount you pay for your electricity per kWh

Feed-in Tariff is the amount your electricity retailer will pay you for the solar electricity you dont use and feed back to the grid. Leave at default if unsure.

Your potential savings will be impacted by the size of your system. The average size system installed in 2018 by Essential Solar was 6 kW.

The appropriate system for your home will depend on a number of factors. These factors include the available roof space, the amount of energy you use, the amount you wish to spend upfront and your expected payback period. No solar calculator is able to provide this level of detail.


100% Australian owned and operated, specialising in solar PV since 2012. We install solar panels on homes and businesses throughout Victoria

Residential Solar

Solar Battery Calculator: Likely Bill Savings

With solar batteries like the Tesla Powerwall starting to feature in the media it can be hard to get to the bottom of whether you should invest in solar batteries or not. This solar battery calculator, intended for those with a UK grid connection, can help show the likely benefit for your own solar system. You can use it to see how much you lose on your investment by buying solar batteries in 2018. It calculates how much of your own solar generated electricity you are able to store in batteries for later re-use.

Use the sliders to adjust the calculator to reflect your own solar installation. The Energy stored per year data is calculated using a real 12-month period of solar generation to represent the day-to-day fluctuations in solar output throughout the year.

The default positions are set for a typical 4kWh solar PV system with average output of 850kWh per year per kW of panel with 50% of generated energy available for export or storage for later use. We have assumed a 2kWh solar battery with a 5 year warranty and an installed cost of £2,500.

Update: July 2019An alternative version of the calculator, allowing for SEG payments, is also available. See Solar Panel & Battery Storage Calculator.

Loss of: £2,094.30

How to use


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