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.

Related Solar Power Articles

• Power, Energy and the Loads List For your New System - A loads list is just a list of all electrical loads that may be employed in the finished system. A 100 watt light doesn’t consume one hundred Watts, since the Watt isn’t a measure of quantity.
• How Many Photovoltaic Solar Panels do you need For Your Solar Powered Home? - If you do not know how many Watt-hours you need to produce, stop here. If you only plan to use the array seasonally, then use the insolation values for those months only.
• How Do You Hook Residential Solar Panels to the Grid? - It may take a little more effort but hooking up your solar panels to the electric grid will save you money and in the long term, reduce the amount of maintenance your solar powered systems require.
• How to Build a Solar Panel on a Tight Budget - Build a solar panel and save yourself money. If you are on a tight budget you can build a solar panel for a very small amount of money, the benefits are obvious; you reduce you energy bills, get paid for feeding electricity to the grid and help reduce CO2 emissions.
• Solar Furnace - How a solar furnace works is by focusing the suns energy on one spot by using mirrors. This article explains how you can create a solar furnace using just two mirrors.