Solar Panels

Solar Panels: How Many Do You Need?

Tie in Your Appliance Use with Your Solar Panel Requirements

To get an idea about the number of solar panels and batteries you will need to generate solar electricity, you will need to make some calculations with respect to the energy used by the appliances in your home as well as how often they are used.

Assessing Power Usage

You need to know such details as the cubic feet of your refrigerator and calculate the wattage based on the number of people who regularly use it. Televisions should be assessed by how much time your family watches the tube per day. The microwave oven can be assessed on its wattage or power rating. Look at the amount of time the microwave is used during the course of a day.

Evaluating Your Use of Lighting

Of course, lighting is a major determinant. Add the total wattage of all the lights in your home. For example, four lamps with 60 watt bulbs in a single room equals 240 watts. Ask yourself – How many hours per day are the lights left on?

Adding Up the Wattage

The LCD display screen on a computer uses less electricity than a CRT computer screen. So, keep that point in mind while making your calculations. Audio systems and printers will also add to the amount of wattage that is consumed. Any other device in the home needs to be figured in as well. Add the wattage and list the hours of use.

picture of solar shingles row of solar panels

Figuring the Number of Panels

Once you calculate how much wattage the appliances in your home are using, then you will have a better idea of how many solar panels you will need for your solar system configuration. Solar panels for average or small-sized residences usually provide 80 to 100 watts of energy. You will need to know how many batteries will be necessary as well.

Wattage x Usage

Typically, the number of solar panels that you will need is based on a 90-watt panel. The batteries for the system are usually the standard 12-volt kind at 105 amp hours. In order to get a clearer understanding of the solar system size you will require, you need to multiply each appliance’s wattage by the daily usage hours. Wattages for UL listed and approved appliances are generally located near the AC power cord for an appliance.

Calculating Voltage and Amps

In some cases, only amps and voltage are given for an appliance. If so, simply multiply the voltage by the amps and you will obtain the wattage – a formulation that is based on Ohm’s Law. So, if you have an appliance with voltage listed at 120 and amps that are 1.5, you would multiply 120 x 1.5 to come up with the answer of 180 watts.

Energy Usage for Refrigerators

In determining the wattage for appliances, such as refrigerators, keep in mind that they will cycle on and off. So, they really run, in actuality, around one-third of the time. Naturally, the more frequently you open a refrigerator door, the more energy is used as well.

Battery Usage

Add all the watt hours for your appliances, then figure your battery needs. Make the assumption that you will need electricity for three days before you need to recharge the batteries. In turn, multiply your daily watt hours by 3.

Determining the Number of Panels

Once you know the wattages and determine the number of batteries you will need, you can easily calculate the number of solar panels to use based on their sizes and wattages.

One Final Note

If you live in an average-sized home (around 1,500 square feet) and pay around $200 each month for electricity, a solar system design of 4 kilowatts may suffice. Of course, the system size, area rebates and where the panels are placed all will determine the size and number of panels utilized.

Watch the video below for more useful tips on solar panels


Renogy Solar Panel Bundle 200Watt: 2 100w Solar Panels UL Listed monocrystalline+MC4 adaptor Cable+PWM 30Amp Charge Controller

25 thoughts on “Solar Panels

  1. Stephen Kuper

    Great video. I would like to go off grid 3brdrm house. Can i turn off the
    main breaker to my panel. Then transfer the house wires to a new panel box
    (same) and hook up my battery bank to it so i don’t have to run new 12volt
    wire to each room and outlets. Can i use existing house wires
    and recepicales. 

  2. SecretHobbies

    Thanks for helping us to understand this better. Cant wait to go solar.

  3. MrTanker10a

    This is absolutely and unequivocally THE BEST introductory video that I
    have seen on how to start with a simple solar system. The idea of building
    one came to me the other day when I was cooking out in my yard early in the
    evening and I could not see what I was doing while I was fixing a couple
    of pieces of steak… So I have decided to look into the construction of a
    small solar-powered lighting system for my cooking island. Thanks a lot for
    the video and I will check out your store on eBay.

  4. TheDisplacedGuy

    Finally someone that explains– EVERYTHING– thank you very much I’ll be
    watching many more. I bought a starter 150 watt kit from Amazon and got it
    hooked to my RV, but I am not sure if I hooked it properly because we are
    plugged into AC, and have a converter too. Does the solar still charge the
    batteries when we are plugged in? Or do we need to deactivate the converter
    when we want to charge? I was able to use the “load” connections off the
    charge-controller and run a small inverter I used to use in my car for
    charging small phones, and running fans, etc. but i want MORE free power.

  5. PhiladelphiaFlyersFan

    Do I have to use the battery or can I just connect it to an inverter, and
    plug in something? Would I need a charge controller for that?

  6. musicgu7

    Thanks! Will check out your other vids now! But for complete newbies like
    me, can you kindly explain watts, amps, volts? I know I can google it but I
    like your way of explaining! :)

  7. Matt Cole

    I am always looking to expand my knowledge. Watching “The Seven Trumpet
    Prepper”, he had Missouri Wind and Solar on, discussing alternative energy.
    While checking out their site, I see they have excellent tutorials on how
    Solar works. Being a newbie to this, I find these videos very well done and
    informative. Check them out.

    Solar panels for the beginner How to Part one Missouri Wind and Solar
    simple instructions

  8. Bernard Francis Sirur

    Thank you. You deserve the “SolarOscar” from the millions on earth.
    Any experience shipping to India.

  9. Vanderbritz Capalungan

    Hi Jeff, quick question tho, at the end of the video, why didnt you hook
    your inverter to “Load” of the the charge controller but directly at the
    battery? thanks! :)

  10. Bruce Marmy

    Advice to the film maker; write/draw a story board, naming the important
    shots to match up to the commentary so that the picture isn’t irrelavant to
    the rambling/mumbling part. It will come over more crisply and hold
    attension of viewers better. Good info.

  11. clark Grizwalt

    My inverter drain the battery before i plug anything in I’ve bought peak
    800 Watts and then thought it was bad so i took it back got another one
    then found out it had a low battery protection thing on it so I took that
    one, back and i got 500 Watts black and Decker still does the same I’m new
    to the solar panel and new to talking on YouTube you’re the first person to
    talk to me on here can you help also i made a video on it

  12. gaz ed

    I have just got a 60 watt solar panel junction box on back has 3
    connectons, with diodes on, 2 outer and one inner connections how wire this
    up ????

  13. clark Grizwalt

    It 12 volt deep cell battery every thing is new bought new at the same day
    it run good for the first few days then i plug a electric burner in and it
    ran for about fifteen minute then it trip the alarm and then now nothing

  14. Corazon de Vera

    If I need to buy a battery for my off grid inverter, what kind of battery
    should I get and what kind of battery should I tell the salesman. Does it
    have to be deep cycle
    or not, vented or not, and how many amps and how many cranking amps, and
    what are the characteristics of batteries that can be used for solar
    panels. thanks and God bless

  15. Glenda Roxas

    Wow this is great solar at the same time wind too… wow, how much would
    cost you in this project?

  16. AzRavnGrl

    You are the DUDE!!! Thank you SO MUCH! I’ve read short “simple” books,
    articles, watched other videos….with yours, I finally COMPREHEND
    it…others make it sound so complicated. Now you need to buy an RV so you
    can explain to us how all the systems work! (I don’t have one yet, but I’ve
    already bought a 128 watt solar panel for it!) Thanks again.

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