Choosing the size of your solar system

If you are are considering switching to solar power for your home, the most likely reason is the great financial saving it will bring. With the utility companies continuously raising their prices, moving entirely off the grid would be an ideal solution. So how do you determine the size of your solar system?

Can I afford a solar system that will provide my entire energy needs?

The answer is: it depends! There are a number of factors that determine the amount of energy that a solar panel can generate. Because these will determine the number of panels your particular home needs, they will also directly affect the cost of the installation.

So how do you calculate the size of your solar system?

Electricity consumption obviously varies from month to month through the year. To keep our homes comfortable, we need to heat them in the winter and cool them in the summer. Our daily consumption also varies, with less current required when we are out of the home during the day. At night our lights and entertainment systems are consuming more energy, and preparing meals adds to the bill.

Taking the total electricity consumption over a year and dividing that by twelve would give you a monthly average. So, it would seem that the size of your solar system would need to be one that could provide this output. Sounds simple, but there are a number of variables which need to be taken into account when calculating this.

Will the size of your solar system be similar to that of your neighbor?

Solar systems will vary in the amount of power they produce based on a variety of factors. This could mean that two houses of exactly the same size may require very different sized installations. Contrary to the popular notion, more panels don’t necessarily mean more power. Two houses may have exactly the same number and type of panels installed, yet produce very different amounts of electricity! For example,  a system installed on one roof may produce more power than one angled in a slightly different direction. So, house “A” on the same block as house “B” may require less panels to produce the same amount of electric current!

Even were the size of your solar system to output the same power as your neighbor’s, your individual demands would vary. We all know that what seems warm enough to someone else, may seem uncomfortably cool to us!

In order to determine the ideal size for your solar installation, you’ll first need to examine a few of the factors that affect both demand and output.

What is the average electricity usage in the United States?

According to Electricity Local monthly residential electricity usage in the U.S. ranges from approximately 531 kWh/month to 1,254 kWh/month.

average electricity usage

The average electricity consumption in Maryland is 1,005 kWh/month, which ranks 20th in the U.S.

This average monthly residential electricity consumption in MD is 11.3% greater than the national average monthly consumption of 903 kWh/month. This means that if the size of your solar system is properly designed, you will reduce your monthly utility bill spending to a fraction of its present level.

Determining the demand and output for the size of your system

While there may be such a thing as an average for a state or region, your electricity needs may vary significantly from that figure. First, determine your average electricity usage from your bills. As we mentioned above, your personal needs may in fact be quite different to your neighbor. Once your installation company has calculated your average daily usage, they will be able to do a free on-site inspection, and devise a system that will meet both your requirements and budget.

Will the size of your system provide affect production in overcast weather?

While panels can produce current at a reduced level during cloudy weather, no current will be produced at night. This means that you will still have to rely on the commercial grid to some extent. However, this doesn’t necessarily mean that you will be paying for this current! The reason for this is that your panels will on average be producing much more current than you need. This extra current is automatically “banked” for you by a system known as Net Metering. Whenever you require additional current during bad weather or at night, you simply draw on this excess current. The way this works is that your system feeds unused current back into the grid, as it is produced, and your utility company “banks” this current by crediting your account. A well designed system can thus basically reduce your electricity utility bills to zero. Read our post explaining this concept.

Battery back up in the case of grid outages

In addition to the size of your solar system, you may want to consider adding a battery backup. With a battery backup for solar system, you have guaranteed continuous power for your essential needs even during an electric grid failure. So, with an independent solar system battery backup, you can continue to enjoy electricity, even when everything around you goes dark.

Read our article to see the many other advantages a battery backup for solar panels brings to your home solar system.

All of this information and more is yours with a free solar analysis and estimate which you can access here at any time.