If you are planning on installing a series of solar panels on your home, then you are definitely on the right track. The fact of the matter is that energy costs are rising rapidly, so anything that you can do to offset those huge costs should be done, especially if it means installing a green piece of technology that will not only benefit your wallet, but the environment around you as well.
Now, with that being said, one of the most important things that you need to consider before you start installing solar panels on your home is how many of them you will actually need. Of course, you don’t want to install a solar panel array just to figure out that it can only provide you with a fraction of your electricity requirements.
Obviously, not having enough is always worse than having too much, because if your solar panel array generates more power than you need, you can always store that excess power in a battery or you can even turn a profit by having that excess energy sent right back into the grid.
We are here to help make sure that you get enough solar panels for your needs. So, how many solar panels do I need? Let’s figure it out right now.
What is Your Current Power Consumption Like?
Of course, before anything else can be considered, you need to figure out exactly how much energy that you use on a daily basis, and preferably also on a yearly basis. If you need to know how much energy your solar panels must produce to meet your needs, then you first need to know what those needs are.
Now, this is a bit hard for us to judge, because how much power you need on a daily basis will depend on a few factors, mainly the size of your house, the number of people using appliances and power, the type of appliances you have, and the climate too. Keep in mind that people who live in hot climates and have to use air conditioning on a regular basis generally spend way more money on power costs than people living in cooler or cold climates.
With that being said, a small house in a temperate area might only use around 200 to 300-kilowatt hours per month, whereas a large home in a hot area might use between 2,000 and 2,5000-kilowatt hours per month.
In terms of the national average, for all American homes, the usage is at around 900-kilowatt hours per month, or about 10,800-kilowatt hours per year, which translates to about 30-kilowatt hours per day or 1.25-kilowatt hours per hour. For the purposes of this article, we are going to assume that you are a totally average household that consumes this exact amount of electricity. So, when it comes down to it, you need a solar system that can generate 30-kilowatt hours per day at the very least (likely more).
In case you need to figure out what your own power consumption for your home is like, all you really need to do is to add up your annual average and divide by 365 days, or add up the monthly average and divide by 30 days, to figure out how much electricity you use on a daily basis. Once again, let’s just assume you use 30-kilowatt hours per day.
The Type & Size of Solar Panel
Ok, so now you have figured out how much electricity you use on an hourly, daily, monthly, and yearly basis. What you need to do now is to take into account that not all solar panels are built the same. Some are more efficient than others and some can produce more electricity than others, given that they are exposed to the same exact amount of sunlight.
First off, the size of the solar panel in question will make a difference, because simply put, the bigger the panel the more power it can produce. However, most residential solar panels come in at around 5.4 by 3.25 feet, with very little variation among manufacturers, so this is not really something that is in your power to control.
However, what you can control is what type of solar panel you get, especially in terms of efficiency. The most common type of solar panel to use for home applications is the photovoltaic or PV solar panel.
Now, these can vary greatly in terms of efficiency and hourly energy production; however, on the low end of the spectrum, the worst solar panels should produce around 150 watts per hour in peak sunlight, whereas the best solar panels out there usually top out at around 400 watts per hour in peak sunlight.
To keep things simple in terms of our example, let’s just go with the average across the board, which is 250 watts per hour in peak sunlight. Your average solar panel will produce roughly 250 watts per hour.
Hours of Peak Sunlight Per Day
Now that you know how much power you need on a daily basis, as well as how much power your average solar panel produces on a daily basis, let’s figure out how much sun you get per day and how this affects power production. Keep in mind that those power production ratings are all based on peak sunlight hours.
Therefore, knowing how many hours of peak sunlight you get per day is very important. On average, most homes will receive about 5 hours of peak sunlight per day, give or take. Of course, this does depend on exactly where you live. So, if you have a solar panel that can produce 250 watts per hour, and it gets 5 hours of peak sunlight per day, it would mean that the solar panel in question would generate 1,250 watts in those 5 hours, or 1.25 kWh.
What is interesting with our example is that 1.25 kWh is how much power an average home uses per hour. Therefore, according to this example, to totally meet the energy needs of your home, you would need a total of 24 solar panels (given that you use 30 kilowatt-hours per day, and given that you have a 250-watt solar panel that gets 5 hours of peak sunlight per day).
Of course, if you have really good solar panels, let’s say ones that can produce 400 watts per hour in peak sunlight, then things look a little different. If this is the case, based on 5 hours of peak sunlight, a 400-watt panel would generate 2,000 watts or 2 kilowatt-hours of electricity in those 5 hours. If this is the case, assuming you still use 30 kilowatt-hours per day, it would mean that you would need 15 solar panels of 400 watts each.
Having a Buffer Zone
The other thing that you should take into account here is that solar panels don’t always work at full efficiency. Inclement weather, shading, and dirt covering the panels can all have their effects.
In order to make sure that your solar panels can generate all of the power you need for a full day, all within those few hours of peak sunlight, it is recommended that you have a buffer of 25%, or in other words, those solar panels should produce 25% more power than you actually need, just to be safe.
This would therefore mean that your solar panels should be able to produce 37.5-kilowatt hours (37,500 watts) of electricity in those 5 hours. If you have 250-watt solar panels, assuming you get 5 hours of peak sunlight per day, this would mean that you would need 30 solar panels.
A Note on Kilowatt Hours & Watts
In case these numbers and calculations are confusing you, particularly in terms of watts and kilowatt-hours, all you need to know is that 1-kilowatt hour or kWh is equal to 1,000 watts. Just move the decimal over three spots. It’s as simple as that.
Conclusion
There you have it folks, everything that you need to know about deciding exactly how many solar panels you will require in order to meet your energy usage needs. Remember that excess power can be stored in a battery for a rainy day, or it can even be sold back to the grid for a tidy profit.