How Do I Know How Many Batteries I Need For My Solar System
Using the result of the above calculation and assuming 200Ah deep-cycle batteries:
Number of batteries needed for 2 days autonomy = 1250Ah/200Ah = 6.25 batteries, each 200Ah
Note: Lead-acid deep-cycle batteries have a recommended Depth of Discharge of 50%. This means that double the calculated Ah will have to be installed:
Number of batteries required = 2500/200Ah = 12.5 each 200Ah
Use the calculator below to find out how many batteries your home would need:
How Many Solar Panels Do You Need
If youre wondering how many solar panels you need to power your home, there are a few important elements to consider. With a few calculations, you can get an idea of how many panels are needed for your home, but if you use a qualified solar panel installer, they will make sure you have an appropriate solar panel system.
To determine how many panels you need, you should know how much energy you use every year. Energy usage is measured in kilowatt-hours and refers to how much energy it takes to run a 1,000-watt appliance for one hour. The amount of energy you use depends on how many appliances are running in your home and how often they are running.
According to the U.S. Energy Information Administration, the average household in America uses 10,649 kWh of electricity each year. To see how much power you use, look at your utility bills from the last 12 months.
Once you know how much energy your household needs, you can begin looking at panels. Solar panel sizes and wattage vary significantly to make it easier to find a system that will work for you. The wattage of a panel, also called the power rating, tells you the electrical output of that panel under ideal conditions. Typically, a panel produces between 250 and 400 watts of power.
You can calculate the production ratio by dividing the energy output by the total wattage of the system. Your production ratio should fall somewhere between 1.3 and 1.6.
System size / production ratio / panel wattage = Number of panels
Best Value Solar Panels: Astronergy 365w
- Cost: $257
- Workmanship warranty: 10 years
- # of cells: 72
- Cell type: Mono PERC
Looking for the best affordable solar panels that wont break the bank? Astronergy makes the best solar panels you can get from a pure value perspective.
Of the major module producers, Astronergy has the lowest cost-per-watt panels weve found. Their 365W panel retails at $257 , which shakes out to 70 cents per watt.
A few of our employees run their home systems on Astronergy solar panels, and we also picked them for the system that powers the Unbound Solar® flagship office.
Their 17.7% efficiency is very respectable at this price point, and the warranty is on par with industry standards.
Astronergy also sets their warranty program apart from other companies by offering third-party insurance. Should they ever go out of business, the warranty would still be valid from the third-party provider.
Thats more for peace of mind than anything. Astronergy is a part of one of Chinas largest electronics manufacturers. We expect them to be around for a long time to come.
But the extra bit of insurance on the warranty coupled with the low price point makes these the best value solar panels.
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How To Calculate Solar Panel Output
Heres a simple formula for calculating your solar panels power output.
Solar panel watts x average hours of sunlight x 75% = daily watt-hours
As an example, lets say you have 250-watt solar panels and live in a place where you get 5 hours of sunlight per day. Whats that 75 percent for? Thats to account for all those variables weve been going over.
250 watts x 5 hours x .75 = 937.5 daily watt hours
To translate this into the more familiar kilowatt hours youre used to seeing on your electricity bill, simply divide by 1000.
937.5 / 1000 = 0.937
To round up and make it pretty, thats 0.94 kilowatt-hours per solar panel.
Of course, you dont have to do this math yourself. Vivint Solar experts will help you through these calculations to find the optimal solar panels for your home. We do this every day and we think its fun. Since we get a lot of questions about how to calculate solar panel output, we decided to share it with you.
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Select Your Mount Type
A roof mount is the simplest and most cost-effective solution since it costs less than other racks. To determine if you can use a roof mount:
2. If a roof mount is not an option, look into a ground mount or pole-mounted solution. On the flat ground, you can position solar panels in any direction you want to maximize sun exposure, unlike on a slanted roof.
To learn more about the pros and cons of each mount type, read this article: Ground Mount vs. Roof-Mount Racking: Whats the Best Way To Mount My Solar Panels?
Recommended Reading: Do Solar Panels Emit Radiation
How Many Kwh Can Your Solar Panels Produce The Complexities Of Production Ratios
The amount of power your solar energy system can produce depends on how much sunlight exposure your roof receives, which in turn creates your production ratio. The amount of sunlight you get in a year depends on both where you are in the country, and what time of year it is. For instance, California has more sunny days annually than New England. But in either location, youll be able to produce enough power to cover your energy needs and say goodbye to your utility billsif you live in an area that gets less peak sunlight hours, youll just need to have a larger solar array system installed at your home. Thus, production ratios differ according to geographic location and a lower production ratio means youll need more solar panels to get the amount of energy production you need.
Ways To Calculate Solar System Size For Your Home
If youre thinking about going solar, one of the first steps youll have to take is figuring out the right solar system size for your home.
Its hard to overstate the impact that the solar system size has on the process of going solar. The size of the solar system will determine:
- The total cost of your solar panel installation
- The amount of roof space required
- The proportion of your power bill youll be able to offset
- The total financial savings over the life of the panels
In other words, you need to first calculate solar system size in order to find out if going solar is worth it for you.
So, what exactly does ‘solar system size’ mean*? What factors affect what system size youll need? And how can you easily calculate the right solar system size for your home? We answer all those questions in this blog.
*If you thought that solar system size refers to the physical size of solar panels, sorry, thats not it!
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How To Calculate Solar Panel Size Needed
If you are looking into purchasing solar panels to be installed on your roof, then you are in for a fantastic experience. They are a brilliant way to provide energy for your home and lower your annual energy bills in one go. Plus, they are environmentally friendly and require hardly any maintenance. However, before you buy, it is important to have a rough idea of the panel size and amount that you will need. Make sure you consult a professional and accredited installer about this, but this page can act as a rough guide.
Don’t Overcharge Your Batteries
Once you have sized your battery bank and solar panel array, determining which charge controller to use is comparatively straight forward. All we have to do is find the current through the controller by using power = voltage x current. Take the power produced by the solar panels and divide by the voltage of the batteries.Example: A solar array is producing 1 kw and charging a battery bank of 24V. The controller size is then 1000/24 = 41.67 amps. Now introduce a safety factor. Multiply the value you have found by 1.25 to account for variable power outputs: 41.67 x 1.25 = 52.09 ampsIn our example we would need at least a 52 amp controller. The Flex Max 60 MPPT Charge Controller would fit our specifications.
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Summary: How Many Panels Do You Need
Knowing the answers to the above questions will give you an idea of the ideal number of panels for your electricity generation needs or at least a realistic range. Next, a professional installer needs to assess your roof architecture, angle to the sun and other factors to see if and how youd be able to physically arrange the right number of panels on your roof to achieve your daily energy production goals.
You should also consider net metering as youre considering how much money youll save and make from your solar system. Net metering is how your utility company credits you for producing excess solar energy when the sun is shining and then lets you draw from those credits when youre using conventional power grid at night, if you dont store your excess solar energy in a battery storage system.
To get started, check out our solar calculator, which can help you figure out how much you might save going solar.
Battery Capacity For Inverters
Now that you understand the different ways to calculate battery capacity, its time to put this information into practice.
For example, you want to power a refrigerator that consumes 200 watts and has an amp hour rating of 100. You will need to do the following:
- Calculate the load in watts: 200 watts
- Convert amps to watt-hours by multiplying amps by hours: 100 amps * 100 hours = 10000 watts-hours
- Convert watt-hours to kWh by dividing the total watt-hours by 1000: 10000 watts-hours / 1000 =
- The battery capacity required for this inverter is: 11 kWh
When sizing a battery bank, its important to remember that you will need to round up the battery capacity required by the inverter. In this example, the battery bank would need to be 12 kWh.
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Solar Panel Specific Yield
After you determine how many kWh of electricity your home uses annually, you’ll want to figure out how many kWh are produced by each of your solar panels during a year. This will depend on the specific type of solar panel, roof conditions and local peak sunlight hours.
In the solar power industry, a common metric used to estimate system capacity is “specific yield” or “specific production.” This can be defined as the annual kWh of energy produced for each kilowatt of solar capacity installed. Specific yield has much to do with the amount of sunlight available in your location.
You can get a better idea of the specific yield that can be achieved in your location by checking reliable sources like the World Bank solar maps or the solar radiation database from the National Renewable Energy Laboratory.
To estimate how many kW are needed to run a house, you can divide your annual kWh consumption by the specific yield per kilowatt of solar capacity. For example, if your home needs 15,000 kWh of energy per year, and solar panels have a specific yield of 1,500 kWh/kWp in your location, you will need a system size of around 10 kilowatts.
Paradise Energy Solutions has also come up with a general formula to roughly ballpark the solar panel system size you need. You can simply divide your annual kWh by 1,200 and you will get the kilowatts of solar capacity needed. So, if the energy consumption reported on your last 12 power bills adds up to 24,000 kWh, you’ll need a 20 kW system .
Which Solar Panel Size To Charge A 200ah Battery
If you have a large 200AH lithium battery, the calculation would be as follows:
200AH Lithium Battery x 12V = 2400WH
1440WH / 8H = 300W of solar panels.
My rule of thumb with solar is that you can never have too much there will be times of the year when you will not get 8 hours of sunlight, there will be overcast days and other factors that prevent you from getting a full day of solar.
Using the above calculation will give you a rough guide as to what you need at a minimum however, it is recommended that you always have more than the minimum.
Another consideration is how much of your battery power do you use in a 24 hour period, if you are only using 50% of the capacity then your solar requirements reduce by 50%.
Click the following link to view iTechworlds solar blanket range designed specifically to charge lithium batteries the most effective way.
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How Many Solar Panels Will You Need To Offset Your Electricity Usage
First I want to address most peoples motivation for going solar: I want to put on solar panels and get my electricity bill to zero!
Getting a zero dollar bill isnt as simple as installing enough solar panels to generate whatever your average daily usage is. As I explained previously, when you use electricity is almost as important as the amount of electricity you use. This is because a solar system only generates its maximum at midday on a good day.
Solar power, regardless of system size, wont do much to a massive electricity bill if its all caused by overnight air-conditioner usage!
Getting zero bills with only solar panels and no battery storage is possible. Until I added an electric car to my home, I regularly got credits on my electricity bills.
Yup my retailer was paying me for the privilege of being connected to the electricity network!
But for those of you with sky-high energy costs and not enough room for a huge solar power system, its important to focus on the amount solar energy can reduce your bills by, not whether or not it can simply get your bills to $0.
Or, to put it another way if solar power could take your $500 quarterly bill down to $50, would you be annoyed you didnt get your fabled $0 bill, or would you be jumping for joy your solar system saved you $450 in 3 months?
Now lets get into some hard numbers on system sizes with the help of my nifty solar calculator.
Example for a typical home in Sydney
Calculate Your Solar System Size
Youre almost there! Youll know how many solar panels your hog farm can use in just two more steps.
For this step, youll need two numbers from previous steps:
Your average kWh you want to produce per month Your hog farms average direct sunlight hours per day
The math looks like this:
kWh per month / = kW solar system
For example, suppose you want to produce 3000 kWh per month on average and your farm gets 5 hours of sunlight per day.
That would be 3000/, which is 3000 divided by 150, which equals 20.
So this particular hog farm would be looking for about a 20kW solar energy system.
If you wanted to produce 2500 kWh, or 3500, just change that first number in the calculation. This is where step 3 comes in. That step is where you decided how much power you want to produce, the percentage of your bill you want to replace with solar power.
If you use 3000 kWh per month but want to produce 75% of your power from solar, you would want a system that produces 2250 kWh per month. 2250 divided 150 equals a 15 kW solar system.
Then youre ready to see how many panels that is.
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Inverter Battery Capacity Formula
Inverter Battery Capacity Calculator calculates the battery capacity required for your inverters. Enter all known values below and press calculate to get the results.
- Battery Capacity = Battery Voltage x Total System Power in Watts / Maximum Discharge Current of the Inverter or Maximum Charge Current of the Inverter
- Battery Voltage = System Power in Watts / Discharge or Charge Current of the Inverter
- Maximum Discharge Current of the Inverter = Watts / Voltage
- Maximum Charge Current of the Inverter = Battery Capacity Required for a Solar Inverter with DC Coupled Battery Charger is the total battery capacity required by the solar inverter.
- Solar Inverter with DC Coupled Battery Charger = System Power in Watts / Maximum Discharge Current of the Inverter.
How Many Solar Panels Do I Need To Power My House
Whether interested in installing your own DIY solar power system or or just curious, the first step in calculating the size of a solar panel array to power your home always begins with energy consumption.
These are the things you need to know before sizing your homes solar system: