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How do I choose my solar panels? Guide to choosing your solar equipment

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Installing a home solar energy system is a smart financial investment for many homeowners. As you evaluate offers from solar companies, there are many different factors to consider – the equipment that you choose for your system, your financing options, and the installer that you select all have an impact on your solar savings. This guide will help you evaluate the different solar panels and inverters available so that you can choose the best equipment for your home. 

There are two main components to a grid-connected solar energy system: the solar panels themselves, which create electricity from sunlight, and the inverter, which converts the electricity into a form you can use in your home. Some also include a monitoring system, which allows you to see how much power you’re creating and using. And while solar batteries haven’t yet hit the mainstream, the announcement of Tesla’s Powerwall battery and other technologies are making it possible for homeowners to consider incorporating a battery into their system.

How to choose your solar panels in 3 steps

  1. Determine solar panel efficiency and compare to industry average of 16-18%
  2. Check solar panel manufacturer warranties against industry average of 10-25 years
  3. Compare cost to relative efficiency – efficiency is important, but the most efficient panels aren’t always the best value

What criteria should I use when selecting a solar panel?

You can evaluate solar panels on a few main parameters: production, durability and manufacturer quality.

The amount of electricity a given solar panel can produce will produce is dependent on several factors, including the power rating, power tolerance, efficiency and temperature coefficient. Taken together, these factors will tell you how much power your panel will be able to produce.

You’ll also want to look at indicators of panel manufacturer quality. Start with the warrantees and assurances that the manufacturer offers on their equipment. Like all things, solar panels degrade and become less efficient over time. Many manufacturers will guarantee that the power production of their panels doesn’t fall below a certain threshold over twenty-five years. In addition, many panel manufacturers have a materials warranty in case the panels simply fail.

Most solar panels are very durable, but if you live in an area that has heavy snow or high wind, you should also be sure that the panels you install are designed to withstand the conditions in your area. Look for panels that meet the IEC 61215, a reliability standard established by the International Electrotechnical Commission (IEC). IEC 61215 uses an accelerated outdoor stress test for panels to ensure their durability.

While some homeowners may choose to invest in the highest quality, most efficient “premium” panels, remember that those will come with a higher price tag. Going solar is a lot like buying a car: not everyone needs a Porsche! Conversely, if you want to save by buying cheap solar panels, your system may produce less electricity over its lifetime, reducing your overall savings. Only you know what is best for your home.

Which inverter should I choose? 

It’s the job of the inverter in your solar energy system to convert the solar energy into something you can use. Solar panels take solar energy and make it into direct current (DC) power. The inverter’s job is to convert that DC power into the alternating current (AC) electricity that can be used in your home.

There are two general types of inverters: string inverters and module-level power electronics (MLPEs). Both microinverters and power optimizers are both MLPEs.

String inverters are the lowest-cost option for a solar energy system. If your system has optimal conditions for production, they are usually a good choice for your home. When your solar panel system has a string inverter, all of your panels feed all of the DC power they produce to a single inverter. The inverter then changes the DC energy to AC power, at which point your solar energy is ready to use.

MLPEs are generally more expensive, but they can also be more efficient. MLPEs are a good choice if your solar energy system may be slightly shaded or can’t be installed at the best angle. When you use microinverters, each panel has its own inverter to transform the power it creates and feed it to your house. Power optimizers, like microinverters, are also installed on every panel, but power optimizers are paired with a string inverter. The power optimizer “conditions” the energy, making it easier to convert from DC to AC, at which point it is sent to the main inverter.

Picking a solar energy provider: how do I choose the right installer?

Your installer is one of the most important factors of your solar installation! When you choose a solar installer, you should review their certifications, licenses, track record and reputation in the market. You should also be aware that a recent report by the U.S. National Renewable Energy Laboratory revealed that large national solar companies charge more than their small counterparts for the same or lesser quality equipment. The recommendation from NREL’s report: shop around and consider local companies.

A great installer, like those on the EnergySage Solar Marketplace, will also use subcontractors sparingly and warranty their workmanship. Most importantly, a good installer will be an effective partner ready to help you go solar. All of the installers you meet on EnergySage have been pre-vetted and meet our standards for all these variables. Whichever installer you use, don’t be afraid to ask questions throughout the installation process.


This post originally appeared on Mother Earth News.


10 thoughts on “How do I choose my solar panels? Guide to choosing your solar equipment

  1. Rob Smith

    Hello! Thanks for such a clear and interesting topic. Very necessary information. Recently I decided to install a solar panel for me and my parents. I think this will help me save money on utility bills for electricity. Also I need to buy a powerful battery that will work solidly under voltage. I am planning to select the equipment and install it correctly. The pricе of solar devices is different, therefore it is difficult to understand which battery is right for me. String inverters are the lowest-cost option for a solar energy sustems, I don’t know if this will suit me. But It’s cool that you can save money and resources after installation.

    Reply
  2. Rebecca Abalos

    Hello,
    We are planning to knockdown our home and rebuild a new home in our land. However, I have 12 solar panels that have been installed 10 years ago. Is it worth to remove the panels and install them on our new home?

    Reply
  3. Victoria Addington

    Thanks for your guide in choosing a solar panel equipment. This July, I’ve decided to shift to solar energy not just only to cut expenses but also to reduce my carbon footprint. With that said, I’ll take your advice to identify the solar panel efficiency and have it compared to the 16-18% average from most manufacturers to make sure that I get the right panels.

    Reply
    1. Packy F

      Voltage is “electrical pressure” meaning is has the potential to do work. IE a car battery (12v) vs home (120v). In a panel it’s of minimal relevance as they are all similar and converted to 120ac anyways

      Amperage is the measurement of the electricity flowing. Amperage is the real work being done. A car ignition can put out 45,000 volts but be of minimal effect when shocked because it has no amperage. On the flip side a Nickel Cadmium (NiCad) battery pack for a remote controlled can discharge so fast it can go to nearly zero volts but have an amperage so high it can (and has) killed.

      Watts is volts times amps. It’s the total measurement of the potential and work being done. It’s how most things electrical are measured. In electronics watts is considered the measurement of heat being dissipated.

      Panels are measured in watts but there are two watt measurements. Stc (standard temperature conditions) which are the max rating the panel gives which is in a climate controlled lab (ideal) condition. NMOT is norm module operating temp. This is the real world output of a panel. NMOT is listed in the specs on the panels. Basically if you have lets say a 440 watt panel (lg neon R) the NMOT is 334 watts if memory serves. Multiply that by 0.9 (resistance and inverter efficiency) and that’s the actual output to expect on your roof. Multiply that by the “sun hours” and thats the total output for the day. You can look up “solar panel sun hours” in google, enter your location and get that. Now multiply that number by the total number of panels and get your total output for the day. It’s quite a bit less than what your seller will advertise but it’s more accurate. Basically a 7KW system will actually produce 4.5-5KW depending on your location and conditions.

      Reply
  4. Tomas Killington

    My brother recently purchased an older home. He has noticed his energy bills are higher than he would like, so he’s looking to get solar panels. I didn’t realize how important it is to consider how durable a solar panel is, especially if you life in an area that has heavy snow fall or high wind speeds. I’ll be sure to share this information with my brother.

    Reply
  5. Cindy Tesler

    Thanks for the tip that the amount of electricity a solar power panel can produce is dependent on several factors, including power rating and power tolerance. You also mention looking at indicators of panel manufacturer quality. I think it’s a good idea to choose solar power for as many things that you can in your home, such as a water fountain.

    Reply
  6. Paul Langley

    This is some really helpful information for any homeowner considering having solar panels installed. I liked your point about making sure that your panels will be able to stand up to heavy snows or other intense weather, because that’s something I hadn’t thought about. And I’m glad you talked about the inverter, because too many people take it as a very unimportant decision. Thanks so much for writing!

    Reply

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