Off Grid Solar Calculator – Solar Panel & Battery Calculator

off grid solar calculatorThis Off Grid Solar Calculator will help you calculate the number of batteries and the number of solar panels you need for your offsite cabin or that boat or RV based on your Solar Panel Kit. Most Solar panel kits  don’t include batteries and those will need to be purchased separately. The solar panels in the kit come in different sizes from 10W going up to 100W and higher. Some kits come with one panel while others have more than one. You invariably need to buy additional panels and batteries. This Off Grid Solar calculator will help you plan your purchases of additional solar panels if any as well as the batteries for the battery bank.

Questions 1 and 2 in the off grid solar calculator ask for information about the appliances you plan to use in your RV or cabin when you are out camping and off grid. The choice of appliances will determine the load. I have included some common loads and you can add anything else you might want in terms of additional loads using Q2) in the off grid solar calculator.

Based on your choices in Q1 and Q2, the off grid solar calculator calculates a daily load in watts which appears after Q6 as “Your daily load in watts”.  Questions 3 and 4  that are about the solar panel in your kit and the number of hours of “bright sunlight” in your area. Please note we are talking of hours of bright sunlight only. For example in NJ in summer that would be about 6 hours.

Questions 5 and 6 are about the batteries. Once you enter the information asked for in these 6 questions, the off grid solar calculator will tell you how many panels and batteries you will need to power the cabin/RV/boat for 1 day. Unfortunately, most of the smaller kits (30W and lower) come with low power solar panels and inevitably require purchase of more panels to run even the smallest of loads.

The calculator on this page is pre populated with information for the Renogy 100W solar panel kit with a 12V, 125AH batteries. You can change all the figures to make specific calculations for your solar panel kit and your loads. You can also see a calculator for a specific solar panel kit by clicking on the “Go to off grid Calculator” link alongside that particular solar panel kit in the table below.

 Eco-Worthy 10W Solar Panel System kit  Go to off grid calculator  Read Review
 Eco-Worthy 20W Solar Panel Kit  Go to off grid calculator  Read Review
 HKYH 30W Solar Panel Kit  Go to off grid calculator  Read Review
 Renogy 50 Watt Solar Starter Kit  Go to off grid  calculator  Read Review
 Renogy 100 Watt Solar Starter Kit  Go to off grid calculator  Read Review
 WindyNation 100 Watt Solar Panel Kit  Go to off grid calculator  Read Review
 Renogy 200 Watt Solar Starter Kit  Go to off grid calculator  Read Review
 Renogy 400 Watt Solar Starter Kit  Go to off grid calculator  Read Review
 WindyNation 400 Watt Solar Panel Kit  Go to off grid  calculator  Read Review

Assumptions : Off Grid Solar Calculator

This Solar Panel Kit – Off Grid Solar Calculator assumes you require enough power from the solar panels to charge the batteries from about 50% capacity to a 100% capacity in 1 day.  If you discharge your battery to very low levels, it will stop working and you won’t be able to recharge it. It is best not to discharge your battery to below 50%. The number of solar panels and batteries is based on the assumption that the appliances indicated will be used for 1 day on battery power. The off grid solar calculator will give you the number of solar panels you will need to recharge your batteries to a 100% every day.

There is a lot more you can do with solar. Check out the solar vents, solar panel kits, solar lights, solar chargers and solar generators . Thank you for visiting

Disclaimer :-  This off grid solar calculator is for illustration purposes only.  Results are approximate. Location, hours of sunlight and battery conditions and maintenance will affect results. Your comments are welcome.

One thought on “Off Grid Solar Calculator – Solar Panel & Battery Calculator”

  1. Hi Steven,

    3 LED Lights for 3 hrs – say 90 watts. Small TV 2 hrs – 90 watts. Laptop and Phone 55 watts. Total of 235 watts. Click on the loads in the calculator above or just enter 235 in the miscellaneous load. I used 35AH for your battery and 50 watts for your panel and the calculator showed you needed 1 panel and 2 batteries. That would make the Renogy 50W kit a good choice. If you want a smaller kit you would need two of the Renogy 20W or HKYH 30 watt kits along with 2 batteries. Happy shopping and thanks for visiting


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