Solar Cells

How Many Solar Cells are Required to Run my House

How many solar cells are required to run my house? The answer to this question is not a simple one. There are a variety of factors that come into play in order for you to calculate the answer. Additionally, there are a number of variables that can make the answer change over time.

The number of solar panels (photovoltaic cells) you need to install to power your home will depend upon your electric power demands, the weather in your area, the angle of your roof, shade issues from nearby trees or buildings and the size of the cells. All of these factors are important and must be built into your calculations so that you can create the best solution for your home and your future needs.

Calculating Energy Usage

One of the hardest factors to determine is your energy usage. This will vary every day. The problem is from day to day, the amount of energy you use is not going to remain consistent; however, you should be able to calculate an average of your energy usage. It is always better to over estimate rather than underestimate.

A good rule of thumb is to first calculate your average daily usage and then multiply that number by .25. This will give you the number and size of solar panels you need in kilowatt-hours. Your electric meter provides you with a very straightforward way of knowing how much energy you are using each day.  Your meter should have either an odometer style readout or a dial type readout.  Your electric company should be able to provide you with instructions on how to read your meter if you are unfamiliar with it.  All you will need to do is record the meter reading and then 24 hours later record the reading again.  This will tell you the kilowatt hours you have used.  You might want to do several readings and average the results you get over a couple of days. If you have kept your energy bills for a couple of years, you can look at these and cross reference your daily usage calculations with your yearly usage.

The average home will use 25 kWh per day, but your usage may vary. You have to consider changes such as additional appliances or changes to your home that will use more energy. Another option is taking the highest usage you have ever had in one day and adding 10% to give you the amount of daily energy you need. You can then source the solar panels (photovoltaic systems) to match that.

Sun Availability

Another variable you have to consider is the amount of sun available. You will need to work out the average number of sunny days, shade issues, and your roof’s angel. All of these factors will let you workout how much sun is available for you to harness and convert in to energy.

The amount of sun required to produce a kilowatt-hour of electricity varies greatly from location to location.  This is due to the variances in the heat of the sun on different areas of the earth.  Many factors will influence how much sun is required to produce a kilowatt-hour of electricity.  The length of the sunlight during the day, the angle at which the sun is shining and the time of year can all affect the energy produced by the sun.  You will have to find out locally how much sun is required to produce a kilowatt-hour of electricity.

Once you determine the average amount, you can compare that to your needs. You can then plan on what to do with any excess electricity you produce.

How much stored energy you need is dependent upon how much energy you are using verses how much energy you are getting. It is always wise to have some type of storage unit so that any unused energy is not wasted but saved for future use. You can store electricity in deep cycle batteries or but a better system, assuming you are not off grid, would be to feed it back into the utility grid.

When feeding electricity to the grid, what you are actually doing is reversing your electric meter and so the electric company can end up owing you money. The important thing here is that it is a lot easier to feed electricity to the grid than it is trying to store it in batteries.

Choosing Solar Cells

Once you have completed your calculations you will need to find the right solar panel. Different solar panels output varying watts and amps. You might want to consider more expensive panels, since they are more durable and efficient which will allow you to use fewer panels overall.

When you are looking at solar panels you will find they are all labelled to tell you how many watts they produce.  One of the larger panels is a 120W.  If you were to get a 120W panel you would need to divide your kilowatt-hour usage per day by the average number of daylight hours per day for your area.  Take that answer and divide it by 120 to get the number of panels you need.

If you are building your own solar panel, you will need 80 about cells to make a 100 watt panel.

You should talk with a professional or a knowledgeable salesperson to help you figure your needs accurately and to help you ensure you get what you need. It is very important that you know the answer to how many solar cells are required to run your house, so that you are sure to get the correct number and type solar panel to meet your needs.


16 Comments on Solar Cells

  1. DOug on Wed, 27th Oct 2010 10:34 am
  2. Yes it’s hard to determine how many panels you need but you can get a rough estimate enough so you will know how much you’ll have to spend.

  3. shishir kumar on Mon, 14th Mar 2011 8:24 am
  4. sir i want 2 know that how many solar panel i requied 2 fit on my roof of my house. i had washing machine, fridge 220lts, micro oven, induction heater, 4-ceiling fans, 6-tubelites 20w each, 2-split ac, lcd tv, desk top computer, music system, grinder with juicer ect.

  5. Rod on Mon, 28th Mar 2011 8:20 pm
  6. I would like to know about how many solar panels I will need for a 2400 sq. ft. home located in Savannah, GA. I have a large refrigerator, chest freezer, washer, dryer, 2 large TV’sheat pump, oven, and numerous kitchen appliences, all electric.
    Thank you, Rod

  7. Paul on Fri, 15th Apr 2011 7:14 pm
  8. Dear Sir,
    I am in the process of introducing solar power to a hotel in Africa, but don’t know how many solar panels I will require to power it? Currently the hotel is powered with a 150kva generator.

    Best wishes,


  9. Millie on Sun, 1st May 2011 6:35 am
  10. How many Solar Panels would be needed to supply a School for a thousand students plus teachers with 5 computer rooms another computer in each classroom and numerouse kitchen appliences for home ec? (average) and a normal 4 bedroom two bathroom home with requred appliances and low energy dish washer, washing machine, heater, cooler ect.? What about a small car? Please tell me how many panels would be requred!!!!!
    Thanks, this is for a school project!
    Millie 🙂

  11. fred poeschel on Fri, 6th May 2011 3:35 am
  12. I would like to know how much or how many panels it would take me to run my home.
    i have washer, dryer, 4 tvs, 2 fridges , 1stand up freezer, stove, 3 ceiling fans,
    and 8 conventional lights 60watts,

  13. Musawir Ali on Wed, 11th May 2011 11:43 pm
  14. sir i want 2 know that how many solar panel i requied 2 fit on my roof of my house. as per day in our area we have a bright 13 hours sunny day, and we can put the panel at any angle, i have washing machine, fridge 220lts, micro oven, induction heater, 4-ceiling fans, 6-tubelites 20w each, 2-split ac, lcd tv, desk top computer, music system, grinder with juicer ect

  15. Tammy on Sat, 21st May 2011 10:38 pm
  16. i would like to know how many panels would be needed to just power my frig. and lights. there mabye just three or four lights on at one time. or just the frig. buy its self with no lights.

  17. Carrie Hardy on Tue, 31st May 2011 8:31 pm
  18. Hello,
    I have a 14 x 68 mobile, very well. Would say, 90 watt help if connected to the grid?

  19. Ardo Nur on Mon, 13th Jun 2011 12:03 am
  20. I would like to know how many solar panel I require for my household. My house will have a washing machine and dryer, fridge 220lts, micro oven, induction heater, 2 ceiling fans, 10 tube lights (40w each), TV, desk top computer, music system, blender, 3 outdoor lights (100w each).

    Your help would be greatly appreciated in how many panels we need.

  21. natalie on Mon, 19th Sep 2011 11:15 pm
  22. our house is 3648 sft. 5 bedrooms, 5 bathrooms. two 52 inches TV, and couple of electric things. so how much it will cost to run all of it.

  23. ab on Sun, 2nd Oct 2011 12:42 am
  24. will like to know how many 45 watts solar panel i would need to power my house of 3 bedrooms, 1 bath, 1freezer chest, 2 fridges, living room, dining room, kitchen, basement, 2 32″ tvs, 2 xbox 360, 2 desktop Pcs, 2 laptops, fax, microwave 900w,blender,toaster,coffee maker, frappe maker, and a small 32 gallon fish tank

  25. ab on Sun, 2nd Oct 2011 12:46 am
  26. ohh forgot the washer and the 220v dryer

  27. bam on Mon, 2nd Apr 2012 3:44 am
  28. hi how many panels will i need? i have 48 washer and dryers, 4789 lcd tvs 14 dishwashers, 5 trash compactors 9 double refrigerators ?

  29. sultan mehmood on Tue, 24th Apr 2012 2:05 pm
  30. sir if i have 220v 500w load how many solar plates i need

  31. sultan mehmood on Tue, 24th Apr 2012 2:12 pm
  32. for 1hp moter 220v how many solar plates i need and how many battries

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