Doing an energy audit to determine your electricity usage is the fundamental and most important step in preparing and planning for your solar or renewable energy system set up in your RV or home.

Knowing how much electricity you use, specifically amp hours will give you a more precise target on which to base the quantity of solar panels and batteries you’ll need to get. And it’s not as hard as it may seem.

To do an energy audit start by listing out all of the appliances you use in your RV or home. You’ll be adding three more columns after the list of appliances so a worksheet might help in organizing all the information. You can download this energy audit worksheet to print out and write everything on.




When considering all your appliances you use, don’t forget to add in your water pump, inverter and any little utility lights or appliance lights that may be on all the time. The inverter will have a constant usage possibly around .5 amps but when it’s inverting a load, the amperage will go up. This is a calculation that shouldn’t be ignored. At the very least, you can add a cushion of about 10% to your entire usage.

Once you’ve listed out all your appliances the next step is to calculate and record the DC amps. If you look on the bottoms or sides of appliances you can usually find information of this sort, often noting either amps or watts. Volts might not be listed because it can easily be assumed to be a 110/120 volt appliance if it runs on AC power or a 12 volt appliance if it runs on DC power.

How will you know which it runs on? What you traditional plug into a house in the US is an AC appliance and if it has a plug that looks like it can plug into your car’s cigarette lighter, then it’s a DC appliance.

There are a couple variations of specs that you may run into and each has their own formula to determine their conversion to DC amps. You’ll have AC amps (when it lists amps on an AC appliance) AC watts (watts listed on an AC appliance), DC watts (watts listed on a DC appliance) and DC amps. If it’s a DC appliance and it lists the amps, you can go ahead an just write that number into your energy audit worksheet in the DC amps column because that’s what we are looking for. For all other’s there’s a quick an easy step to calculate.

If it’s an AC appliance and it lists the amps, take that listed number and multiply by 10 to get DC amps. Once you’ve multiplied by ten then enter that new number (the DC amps) into your your energy audit worksheet. If it’s either an AC appliance or DC appliance and it lists the watts, then you can take the watts number and divide it by 12 to get DC amps. Take that new number and enter it into your worksheet in the DC amps column.

It should also be noted that reading the rated amps or watts on an appliance will list the highest usage that the appliance might require. Sometimes, it will only peak to that number when turning the appliance on. It’s a good idea to use this higher rated number to allow more cushioning in the calculations. It’s always better to have prepared for a higher amount of usage than to fall short of your need.




After you’ve calculated your DC amps for all your appliances then you need to write out the number of hours you use these appliances in a 24 hour period. Keep in mind that if you only use the appliance for a minute or two a day the number of hours you must list will be a fraction. For example if you use your blender for 1 minute a day, that’s 1/60 of an hour or .02.

After you’ve completed the DC amps column and the hours per day column then you can multiply each appliance’s DC amps by the hours you use them to get the total daily amp hour for that appliance.If you are following along on the energy audit worksheet that you can download from this site, once you’ve calculated all the appliance’s daily amp hours then you’ll have a column of those totals. Now add up all those totals to get the total daily usage of energy that you use.

This total daily number is what you need to determine how many batteries and how many solar or PV panels you’ll need to satisfy your energy needs.




Let’s says your total daily amp hours is 100. You’ll need at the very least, a battery with a storage spec of 200AH. That way you would only ever run your batteries down to 50% of the capacity. If you only wanted to use the top 20% of your batteries you would need to multiply your daily AH usage by five. In this example with the total daily AH being 100, multiplying by five would mean you need 500AH of battery storage to only use the top 20% of you batteries.

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