Solar Power Potential: Is My Home a Good Fit?

Tori Barrington

Good Fit Solar
Key Points (TL;DR)
  • Solar panel efficiency decreases in the heat, so if you live somewhere hot, pay attention to the temperature coefficient of the panels you purchase.
  • Your geographical location will affect how many hours of daylight your solar panels get at different times of the year.
  • If your roof is not in optimal condition, replace or repair it before installing solar panels.
  • Do not place solar panels in shaded areas. If there is some shade that comes and goes during the day, we recommend using microinverters.
  • The size of your roof determines how many solar panels could fit, which affects how much energy your system would produce.
  • Q&A
    Should I invest in solar if I live somewhere cold? Yes! Solar panels need sunlight to function, but they become less efficient in extreme heat. Solar panels perform at peak efficiency at 25°C (77°F) and slowly lose efficiency each degree above that temperature.

    Because of this, solar panels work better at colder temperatures.

    Can I still get solar panels if there is some shade on my roof? Yes! While you should avoid placing panels in spots that are shaded during peak sunlight hours, microinverters can help.

    Microinverters are attached to each solar panel, so if part of a solar panel is shaded, the efficiency of only that one panel will decrease. If the entire system only has one inverter, that little spot of shade would decrease the efficiency of the whole system.

    If there is some shade on your roof, invest in microinverters.

    What if my roof doesn’t face south? Don’t let the direction your roof faces determine whether or not you buy solar panels.

    Solar panels are exposed to more sunlight if your roof faces south, but if it faces any other direction, it will still absorb sunlight during the day.

    When researching solar, you should have a realistic idea of how much solar power your home will be capable of generating.

    You are probably hoping that your home will produce enough electricity to eliminate your energy bill altogether. While this is possible, it is important to consider a variety of different factors before installing solar panels with high expectations.

    The following are aspects of your home to examine and questions to ask to determine if your home would be a good fit for solar panels.


    Is the weather hot where I live?

    It is easy to assume that more heat equals more sunlight, and therefore hot weather is ideal for solar panels. However, a solar panel’s efficiency can decrease in the heat.

    Each type of solar panel reacts differently to the heat. Some see a significant decrease in efficiency in hot weather, while others, like monocrystalline panels, are not as affected by the heat.

    This question is important to consider when choosing a model and brand of solar panels as well. Each solar panel has a temperature coefficient, which is the percentage of efficiency lost each degree above 25°C (77°F). Solar panels are tested in conditions set at 25°C, so they perform their best around that temperature.

    If you live in a consistently hot climate, you should look for a solar panel with a lower temperature coefficient.

    For example, if a solar panel has a -0.3%/°C temperature coefficient, that means its efficiency will decrease by 0.3% for each degree that exceeds 25°C. If your solar panel is 30°C, that is 5°C higher than 25°C, which means that it is 1.5% (0.3x5) less efficient than normal.

    This change may appear insignificant, but during the summer in a hot climate, solar panels can reach 65°C (149°F), which would significantly decrease efficiency.

    See the graphic below for information on the top states for solar power in the United States, including temperature, average peak hours of sunlight, and number of sunny days during the year.

    Heat Map 2

    Is it more likely to be cloudy or sunny outside?

    Solar panels convert sunlight into usable electricity, so sunlight plays a necessary role in the process.

    However, this does not mean that if you live in a rainy or cloudy place you should not invest in solar. Solar panels can produce electricity through indirect sunlight, so they still function on cloudy days.

    You can expect solar panels to operate at 10% to 25% of their usual efficiency on overcast days, depending on the density of the clouds.

    Is it humid?

    Humidity can also have a negative effect on solar panel efficiency.

    Humidity is the amount of moisture in the air, so consistent humidity can cause small water droplets to form on top of the solar panels. As the sun shines down on the surface of the panels, the tiny droplets can reflect the sun rays away, which decreases the amount of sunlight the panel is able to absorb and convert into electricity.


    How much shade is cast on my roof?

    Shade can also impact the efficiency of your solar panel system by blocking access to sunlight. Pay attention to any tall trees or buildings nearby that may be casting shadows onto your roof that you haven’t noticed before.

    Take note of the time of day that the shade occurs. Shadows on your solar panels will have less of an effect if they occur early in the morning or late in the afternoon.

    Solar panels should be performing at their best with direct sunlight, and prime sunshine hours are about a couple hours before and after 12:00 PM. Even a small amount of shade on a section of a solar panel during these times can drastically reduce efficiency, causing the system to operate at half its optimum capability.

    If you can, avoid placing solar panels on the parts of your roof that receive consistent shade during peak sunlight hours.

    If there is some shade but there is no way to avoid it, don’t worry. Microinverters or power optimizers should help solve this problem.

    A solar panel system that has one centralized inverter will be more affected by the shade, because if one panel is shaded, the entire system will take a hit. However, microinverters and power optimizers are attached to each individual panel, so if one panel is shaded, only that panel’s efficiency will decrease.


    How long are the days where I live?

    Your geographical location affects how many hours of daylight your solar panels will receive every day.

    While everyone’s days get longer in the summertime and shorter in the winter, some states have even longer or shorter days, and therefore even more or less sunshine.

    For example, in June, Arizona’s days last 14 ½ hours while Montana’s days last 16 hours. But in December, Arizona’s days last 10 hours and Montana’s days last 8 ½ hours.

    More hours of sunlight will allow the solar system to produce more usable electricity. It is important to take location into consideration to have a realistic expectation of how much power your system will produce at different times of the year.


    Is my roof in good condition?

    Your roof should be strong and durable to hold the solar panels, and you want the roof to last as long as your solar panels will. Solar panels are built to last about 25 years, so make sure your roof is in good enough condition to last that long. It would be a pain to replace your roof after solar panels were already installed.

    Perform a quick inspection of your roof using the following questions:

    Inspect Roof

    If you answered yes to any of those questions, you should look into getting your roof replaced before you install solar panels.

    Which direction does my roof face?

    Solar panels will perform the best if your roof faces south, because they’ll be exposed to the most sunlight that way.

    South-facing is ideal, but if your roof faces another direction, you can still get solar panels! Solar panels on your roof might absorb less sunlight, but that doesn’t mean you should abandon the dream to live on clean energy and be free from expensive utility bills.

    How big is my roof?

    The size of your roof impacts how many solar panels you could fit, therefore affecting how much power your solar system would produce.

    Each solar panel is about 17.5 square feet. What is the size of your roof in square feet? You can calculate how many panels could fit and how much power they would produce.

    For example, if your roof is 1,750 square feet, you could fit a system of 100 solar panels. If each was a 350W panel, the system would be 35kW (100 panels x 350W), producing 175kWh (35kW x 5 hours of sunlight) of energy each day.

    Your roof size allows you to calculate how much energy your solar system would produce, which helps answer the question - would a solar panel system produce enough energy to decrease my utility bill?

    Air Quality

    Is there a lot of pollution where I live?

    Pollution in the air can filter sunlight, decreasing the amount of sunlight that reaches solar panels.

    If the pollution is thick enough, dirt and debri can slowly build up on the solar panels, also negatively affecting efficiency.

    Is my house a good fit for solar panels?

    After answering the questions mentioned above, hopefully you have a better idea of your home’s natural fit for solar.

    But don’t forget that even if your home isn’t perfect, there are solutions to make solar work for your unique situation.

    If the climate is especially hot where you live, invest in monocrystalline panels and find a model that has a low temperature coefficient.

    If there is some shade on your roof, avoid the spots that have the most shade during peak sunlight hours and buy panels with microinverters.

    If your roof isn’t in great condition, you can get it replaced! You can also try to find a company that replaces roofs and installs solar panels, like Solar Optimum.

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