How to Calculate Solar Panel, Battery, and Inverter Specifications – Choosing the Right Solar Equipment for Your Solar Power System
Calculating your solar power needs and sizing the necessary solar equipment is one of the most important steps you will need to take when building any type of solar power system.
While some people assume that the only calculation you need to make is buying solar panels with power ratings that add up to your desired amount of electricity, there are other important calculations you must make. For starters, it is just as important that your batteries, power inverter, and charge controller also work together. Unless everything matches up and is compatible, your freshly assembled solar power system will not work efficiently, or at all.
That is why we are here to help you choose the right solar equipment for your specific power needs. We will explain how you can quickly calculate how many solar panels you will need and what type of solar panels they will need to be. From there, we will explain how you calculate solar battery amp-hours and choose an appropriate charge controller and power inverter.
Once you know what sort of equipment you will need, you can assemble an efficient solar power system that will actually meet your power requirements.
Estimating How Much Power You Will Need
The first step you will need to take before you purchase any solar equipment is calculating how much power you will actually need. In most cases, this involves estimating your load wattage.
You load is the total amount of electricity required to power the devices or appliances you plan on running with solar electricity. Properly calculating load consumption is a critical step in properly sizing each and every component in your solar power system.
You will need to purchase solar panels that can meet those load requirements, a charge controller that can properly regulate that amount of electricity, a power inverter that is compatible with the system’s requirements, and deep cycle solar batteries that are actually capable of storing that amount of energy.
To keep things simple, we will assume that you are looking to power a device that uses 100 watts for 10 hours per day. You would then perform a simple calculation to get the watt-hours, or Wh, for that particular load. In this case, the equation would be 100 watts x 10 hours = 1,000 watt-hours.
If this was all that you were planning to power with your solar power system, you would need enough solar panels to power 1,000Wh per day.
For a more detailed explanation of how you would add up your solar watt-hour requirements, take a look at our Ultimate Off-Grid Solar Watt Hour Calculator.
Determining Solar Panel Requirements:
Once you have calculated your load in watt-hours, you will need to determine the type and number of solar panels you will need to satisfy your estimated load requirement.
Solar panels are given a power rating in watts according to the amount of electricity they can produce in a single hour of direct sunlight. So, if you had calculated that you needed 1,000Wh to meet your load requirements, a 100 watt solar panel that was exposed to 10 hours of direct sunlight would work. (1,000Wh / 10 hours = 100 watt solar panel)
However, you need to factor in the real amount of sunlight your solar panels will actually receive per day. Everything from the clouds in the sky, to the particular season when the solar panel is being used will impact the amount sunlight a solar panel can absorb each day.
When calculating the amount of sunlight your solar panels will receive per day, always be cautious about overestimating. Assume that there will be cloudy days and factor in where you live and the differing amounts of sunlight your location receives throughout the year.
Once you have calculated your load requirements and have a reasonable estimate of the average daily sunlight your location receives, you can begin shopping for solar panels. Browse our Full Solar Panel Collection and you will find a wide selection of high-quality solar panels with a variety of power ratings.
Calculate Your Battery Requirements
Once you have calculated your power requirements and know the number and type of solar panels you will need, you must calculate your storage needs.
To choose the correct solar batteries, you will need to calculate the Amp Hours/Ah rating your batteries will need to meet your load conditions. To do so, you will calculate that number by dividing the watt-hours by the volts.
Assuming you are planning to run 12V solar panels and 12V batteries, you would divide your 1,000Wh by 12V to get a total of 83Ah. So, in this example, a 100Ah 12V deep cycle solar battery would be able to meet your storage requirements.
Deep Cycle Solar Batteries:
Deep cycle solar batteries are specifically designed to withstand the repeated charging and discharging cycles that occur when you are dealing with solar power. You can wire multiple solar batteries together in either a series or parallel connection to achieve different voltages and capacity totals.
For more information about solar batteries, as well as a complete list of the options we carry, browse our Complete Collection of Deep Cycle Solar Batteries. We offer a wide range of high-quality solar batteries from some of the best brands in the entire solar industry.
For those looking for a rugged and reliable lithium-ion solar battery at an affordable price, we always recommend the BattleBorn 100Ah 12V Deep Cycle Battery. Not only does it offer a built-in battery management system, it comes backed with a 10-year warranty.
Evaluating Charge Controller Specifications for Your System
At this point, it is worth stressing that the amount of power your solar panels can generate will spike, as well as drop. Which is why you will need a charge controller with the appropriate specifications for your solar panel array and battery bank.
Charge controllers prevent overcharging, which can permanently damage the batteries in your system. The best charge controllers also prevent the reverse flow of current from the batteries to the solar panels, which can occur at night when the solar panels are not producing electricity.
To choose the correct charge controller for your solar panels and battery bank, you will need to assess the current, or amperage specs, of your solar panels. You can calculate this by dividing the wattage rating of your solar panels with the voltage.
For example, a 100 watt solar panel / 12V = 8.3 Amps.
When choosing a charge controller, you can always round up a bit; however, you do not want to leave too much room, or you risk overcharging your batteries. In the case of our ongoing example, a 10A charge controller would do the trick.
If you are in the market for a charge controller, we encourage you to browse our Charge Controller Collection. We carry a wide variety of MPPT and PWM charge controllers and we carry everything from 8A controllers to 80A units.
Assessing the Required Power Inverter Specifications for Your System
The final piece of equipment you need to calculate the specifications for is the power inverter. In simple terms, the power inverter converts the DC power your solar panels generate into more practical AC power, which is what most electronic devices and appliances require.
Since, by this point, you would already know the maximum load wattage, you would want to choose a power inverter that would be capable of handling that wattage comfortably.
In the case of our example, the maximum load wattage is 100 watts, which means that you would just need to choose a power inverter that is rated at 100 watts, or slightly over, as spikes do occur.
You will also want to factor in your chosen power inverter’s voltage rating, as it is important to match the voltage rating of your power inverter to the voltage of your battery bank. So, if you were running a 12V battery bank as part of your solar power system, you will want to buy a 12VDC power inverter, as this will allow your inverter to convert that 12V DC power into 12V AC power.
Choosing the Correct Power Inverter:
For more information about power inverters, as well as a full list of all of the options we carry, feel free to browse our Complete Solar Power Inverter Collection.
Purchasing a Complete Solar Power Kit
If you would like to save yourself the headache that goes with making sure all of your solar components are compatible and will run efficiently together, you can always choose to purchase a complete solar kit.
Not only are solar kits a great idea for beginners, the fact that the equipment is bundled together means they can be offered at discounted prices. In most cases, the individual pieces of equipment are offered at much lower prices as part of a bundle than they would be if you wanted to purchase them separately.
A complete solar power kit will come with everything you need, including solar panels, a charge controller, power inverter, a deep cycle solar battery, and all of the cables and connectors you need to wire everything together.
For those looking to purchase an affordable solar kit that contains high-quality components, we recommend taking a look at our Renogy Solar Kit Collection. Each kit was assembled to strike the perfect balance between convenience, performance, and affordability. They are also available in a wide range of power ratings, so you can find exactly what you need.
If you have any questions about assembling your own solar power system, or calculating power specifications for specific pieces of solar equipment, you can contact us at any time with your questions!
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