You can freely use this Off-Grid Solar Calculator to design a solar power system for your office, house, or workshop. Off-grid systems work independently of the grid but have batteries that can store the solar power generated by the system. The system usually consists of solar panels, battery, charge controller, grid box, inverter, mounting structure and balance of systems. Start designing now. Manually fill the appliances, their wattage and hours of use. If you find this calculator helpful don’t forget to comment your opinion below in the comment section. Thanks in Advance,
Use the Total Power Consumption Calculator to find out the total power use per day and total connected load in your property.
DIY Solar Inverter Step by Step Design and Calculation
If you want to know how this off-grid solar calculator find out the ratings of each and every component of a solar power system I am glad to explain it here. I think you already know the total power consumption of your house or property and the total connected load in watts. You can use my total power consumption calculator to easily find out these. Let’s assume We need 2500W power and the total connected load is 350W. We are using small values for easy calculation.
- Total Power Consumption is 2500Wh
- Total Connected Load is 350W
Inverter rating should be Greater than the total Connected Load. So the inverter we are going to use with this system can be 500-1000W.
The inverter should provide 2500Wh output a day. Every inverter has an efficiency factor. This means it cannot provide the same amount of power we give to it using batteries. We assume a typical inverter has 80% efficiency.
Input power = 2500/0.8 = 3125Wh. (Battery Power)
Every battery has Charging and discharging losses. Here we again consider battery efficiency as 80%. It is not the depth of discharge. We will take that into account later.
Actual battery power = 3125/0.8 = 3906Wh
Actual Battery in Ah = 3906 Wh/12 V = 325 Ah
Every battery has a depth of discharge. Foe Li batteries it is more than 90%. Modern lead-acid batteries designed for solar applications have nearly 80% DoD. Considering DoD as 80%,
Total Battery Ah = 325Ah * 1.2 =~ 400Ah
Total Battery Ah should be 400Ah. This means You can use a single 400Ah 12V battery (12V system) or two 200Ah 12V batteries in series. (24V System)
Then there is a charge controller. It is what regulates the power coming in from the solar panel. A solar controller also has an output efficiency of 90%.
Charge controller input power = 3906/0.9 = 4340Wh
When you divide this value by peak solar hours in your area You will get the Solar panel size.
Solar panel size = 4340 Wh / 5.5 h= 789~= 800 W
Thats how off gris solar power system is sized. If you have any doubts or suggestions kindly use the comment section.
Hello,
I have watched your YouTube videos on DIY solar panel system, and I am very impressed with the way you explained things. I am a complete beginner and I have yet to build any solar panel systems, even a very basic one. I have seen that you provided the list of components that you used to build the “How to Setup a 250W Solar Inverter” project. Will you be able to share the details of the breakers that you used to between the charge controller and the solar panels, charge controller and battery and between battery and inverter? Information about the fusebox and light switches, will also be very helpful.
If I do a design, before building my first system, can I share with you, and you can advise me if it is correct or not?
Since I am a beginner, I will start with a single panel design before moving to multiple panels.
Thanks very much in advance.
Pls check my last video on 800 W solar inverter. Everything you asked is explained there.