Last Updated on 2 years by admin
Calculating your own electricity consumption looks like a simple task. But if you don’t do it right, you might not get the best out of your off-grid solar system. Here’s a better way to calculate and design the Right Off-Grid for your home.
Plan Your Off Grid
First, decide why you need an off-grid system. Most common reasons are to reduce electricity bills or to be able to use electrical items even during a grid power loss. Once you decide which of the above options suits well, then you need to move to the next step design right Off-Grid.
Categorize your items
Depending on your previous decision, categorize the electrical items that you currently own. And note down the item name with the wattage of each item. You can use the user manuals to check the wattage in most items if not refer to the manufacturer’s website.
Now list down the items that are required to be connected to your off-grid system.
Doing the listing in a spreadsheet will support you during the next calculations.
Best practice is to have some free capacity for future upgrades.
Calculate your Wattage
Once you have finalized the item list with wattage as guided above, the next step is to do the calculations. Don’t worry, I am going to make the process as simple as possible.
First divide the day into two 12hour slots. Slot 1 – 6am to 6pm and Slot 2 – 6pm to 6am. This can be done by adding two rows to the above spreadsheet. Here’s how you need to do the calculation. If you use two numbers of 5W LEDs from 6pm to 6am, the calculation will be of 5W × 2 × 12h = 120Wh. Do the same for all your items. This step is critical to design right Off-Grid system.
Decide the battery for your Off Grid system
For example, if the total watt hours of your calculation come around 1000Wh, and you want to build a 12V system with a battery of 1000Wh / 12V = 83Ah. This is the exact amount of the battery capacity you need. But if you are using an inverter, put an additional 15-20% on the loss of the inverter. Calculation example – 83 × 115% = 95.45Ah.
If the battery type is lead acid, double the number of batteries required. Example: 95.45 × 2 = 190Ah, Put at least 180-200Ah battery.
Now you need to calculate your solar panel / panel array
If you use any devices during the day while charging this battery, that is the minimum panel capacity you need. But the minimum amount will not support your nighttime usage.
Example, a typical single door fridge(70W), an Internet Router(10W), a laptop(40W) Total = 150W. This is the minimum size of the required panel for daytime use. But suppose the system includes a 1000Wh battery, we need to charge it in at least 5 hours. (Assuming maximum sunlight is 5 hours) 1000/5 = 200 + 150 = 350W is the required panel.
As said above to minimize the complication of the calculation process I have shared a wonderful calculator which I found on web. This could help you design solar system online – This google doc does the job with few clicks.
Hope this article supports to design solar system for home with the right calculations. If you have questions, please reach out through comments. Also special thanks to the original creator of the Google Doc.
