Home » Solar » Solar Panel Size Guide: How Much Do You Need For Your Home?

There’s a lot to take into consideration when setting up own your solar panel systems to create your own off-grid solar energy. It can sometimes be overwhelming if you don’t have all the answers. Thankfully, this guide is here to help put your mind at ease and will take you through one of the most important factors of investing in a decent solar panel system: What size system do you need for your home? At the end of the guide, you should have a much better idea as to the size of system you need to meet your requirements.


Determining the wattage

This is the most important part in deciding what size solar panel to get. Underestimating the amount of solar energy you need, will only lead to disappointment. On the other hand, overestimating how much you need, may cause you spend more than you need to. As a rough guide, a solar panel that’s one square meter in size could potentially generate around 150 watts of off-grid solar power.

To determine what wattage you’ll need for your solar power systems, first you’ll need to make a list of all the electrical items that you want to keep powered by the battery. Then you’ll need to find out each item’s wattage. This information is usually located on a sticker on most electrical items. Once you have that you can work out how much energy you’ll use. For example, a 100w TV that’s on for 4 hours a day will consume 400wh from the battery. After you’ve done this for all the items on your list, the total figure added together will give you the number of daily watt hours you require.

Calculating the solar panel size


The next part of the equation, once you’ve determined the number of watts hours you require, is to calculate the size of the panels you need to provide for this. To do this, simply divide your daily watt hours needed by the number of hours of light you’d expect in a typical day. So, if you calculated your daily watt hours to be 10000 and the average number of hours sunshine you get per day is 5, you’ll need a minimum of 2000w (2kW) in solar panels to be able to provide for this.

Calculating the physical amount of space required

Solar panels come in all kinds of shapes and sizes, with most being between 150w to 345w per panel. The smaller the panel and the higher its wattage, the more you can expect to pay for it. To give you some idea of the kind of size we’re talking about, an average 250w solar panel measures in at around 1.70m x 1.00m. So, in the example above, for a 2kW system, you would need 8 of these solar panels. This equates to an area of 13.60 m x 8.00 m and is the minimum amount of space needed to set up a system of this size using this type of panel.

If you are short on space that doesn’t mean to say you need to forget the idea of solar panels, you just need to find the right balance between space and power. Go back to the items on the list you made when determining the daily watt hours you need. Try and cut this down. If you’re looking to add a solar system to your home just to help in times of power outages, then you really don’t to have a huge amount of items on the list. Just stick to the essentials and rework the calculations. You’ll soon find a balance that works for you. If you’re looking to install a solar power system to help cut down the bills, then anything’s a bonus, right?

Factors that may affect a solar panel’s efficiency

In order to get the most out of your solar panel system, consider these factors:

  • Material of the solar panel: The most efficient solar panel available today is made from monocrystalline, with those made from polycrystalline coming in at a close second. Thin-film solar panels are also available but take up a lot more room and are pretty inefficient in comparison.
  • Positioning: For maximum efficiency, solar panels need to be positioned in a place where the input of sunlight is at its greatest. In the United States, this is toward the South.
  • Shade: This is solar power’s worst nightmare and even the slightest shade can bring a solar system to a halt. Because solar cells are all interlinked if even one cell becomes shaded, it can adversely affect the efficiency of the rest.
  • Lifespan: Like most things, solar panels will degrade over time. However, in general, they’re pretty efficient and most manufacturers guarantee an output efficiency of at least 80% even after 25 years.
  • Soiling: If solar panels are covered with bird droppings they’re not going to be able to absorb the light effectively. Cleaning your solar panels frequency will ensure you get the maximum efficiency from them and will also allow you to inspect them for any signs of damage or wear and tear.

It may not always be possible to power your whole home by solar power if you consume a lot of energy and don’t have much roof/outdoor space available. However, even using solar panels to harvest energy to use when electricity rates are higher, it will save you a great deal of money in the long run. If you have a solar battery included as part of your system you’ll also have the peace of mind that if something such as a power outage does happen you’ve got sufficient backup for at least a few hours.