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10 common solar panel installation mistakes and how to avoid them

Going solar is no small feat and it’s easy to mess it up. “Learn from your mistakes,” they say, but you may as well learn from the mistakes of others. In this article, we’ve collected popular mess-ups: here is our list of 10 common solar panel installation mistakes and how to avoid them.

1. Going solar blind

Getting a home solar system is not rocket science, but it’s best to do some research beforehand.

Learn the Basics. Start by getting a fundamental understanding of how solar energy works and the components of a solar system. Make sure you understand the benefits and disadvantages of a home PV system. Think about what kind of system you want: grid-tie, off-grid or hybrid. To start, check out our article on how solar panels work.

Inquire about net metering. In a nutshell, net metering is selling your excess solar energy into the grid. Each state has a different net metering policy: the size of a system to be eligible varies, and the rates at which you’re compensated change from utility to utility. It’s best to contact your operator and learn the terms. Read our article about net metering to learn more. 

Ask about permits. The procedure of getting a solar system is different in state, county or municipality. Local authorities often publish guidelines for those who want to go solar on their websites.

2. Sizing the system wrong

Solar systems may appear complicated. When people say that they didn’t get what they wanted from a solar system, the common reason is that their installation was sized incorrectly and couldn’t cover the needs of a house. When you’re planning your system, you have to understand how much energy a solar panel actually produces.

Vasilii Smirnov
Solar Installation Expert

Many homeowners don’t know the difference between the DC rating of a solar system and its AC production. You can’t expect a 7-kilowatt AC power output from a 7-kilowatt DC system. Imperfect irradiance and positioning, high temperature, equipment inefficiencies — all these contribute to power losses in your PV system. On average, a solar system produces about 20-30% less AC than its DC rating.

7 kW

average home solar system size in the US

Can a system be too big? Yes, it can. If it produces way more than your house needs and you can’t sell the energy to the utility, you oversized it. Utilities have different policies on how they buy solar energy from customers. Some refuse to offer net metering to systems that are, say, over 10kW. Some set a limit on how many of your kilowatt-hours they are willing to pay for in a month. It’s best to contact your electric provider when you are still planning a system.

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3. Choosing wrong panels

PV modules are the core part of a solar installation and picking them right is a must. When it comes down to the choice of solar panels, mistakes can cause your system to be inefficient or more expensive than it has to be.

Pick monocrystalline panels! Start with the type: monocrystalline panels are the best for a home or a commercial installation. Polycrystalline panels are slightly cheaper but inefficient and take up a lot of space. Thin-film panels are used in mobile installations, such as RV and boat systems, and it makes zero sense to build a home system out of them.

Consider larger modules! In 2020-2022, home systems were made mostly out of 300W-350W panels. The average size has grown and 400W-450W panels have become much more popular. Powerful modules are harder to fit on the roof since they are larger, but you can build a system with fewer panels this way.

Put the specs first! It’s easy to overpay for the brand. There are over 350 solar panel manufacturers on the market and newcomers are naturally drawn towards familiar names like LG or Panasonic. While their panels are great, they are sometimes 2 times more expensive than average. Look at the specifications of the panels and not the brand!

Check out the video on Top 5 solar brands on our Youtube!

4. Ignoring solar incentives

The government wants citizens to go solar. That’s why it devised programs that make installing solar panels easier and cheaper. Not making use of these incentives is unreasonable.


Solar Tax Credit expiration date

Solar owners should always take advantage of the Federal Solar Tax Credit. It lets you deduct 30% of your installation cost from income taxes. For example, if the solar system costs $15,000, you could claim $4,500 back. Total solar installation cost includes inverters and batteries, as well as labor and shipping expenses.

Solar Tax Credit is the most important incentive, but it’s not the only one. Some states have their own local solar programs. In many states, solar panel systems are exempted from property tax. Utilities sometimes offer small rebates for the customers that go solar. Find more programs in our article on how to save money when going solar! 

5. Leasing a system or taking a loan

Leasing a system or taking a loan to buy it was a popular way to go solar a decade ago. Since then, the panels have dropped in price by 80%. Paying in cash became easier and this option guarantees the highest savings from a PV system.

Think about it like this. A solar system brings you $100-$200 every month. Monthly payments to a leasing company or a bank amount to around $80-$100. As a result, you are barely making money with a solar system.


 average personal loan interest rate in 2023

The experts from Google project Sunroof calculated that a 4kW solar system in California brings $30,000-$50,000 over its lifetime. If you pay in cash, your profits after 20-25 years will exceed $20,000. But if you lease a system or take a loan with 6% interest, your earnings decrease to only $2,000-$5,000 by the year 25. 

Some banks offer loans for clean energy projects and energy-efficient home upgrades, including solar panels, with an interest rate as low as 4%. This is a compromise for those who aren’t ready to pay upfront for a whole solar system.

6. Installing a grid-tie solar system by yourself

Labor expenses make up to 50% of the whole solar system cost. If you consider installing solar panels yourself, you must be confident in your skills. We don’t want to doubt them — we’re just saying that grid-tie solar systems particularly aren’t DIY-friendly.

The problems are legal constraints, safety regulations and building codes that you wouldn’t know about unless you make a living by installing solar panels. In some states, you can perform the installation only if you a licensed solar contractor. Connecting your solar system to the community grid is only possible if the electricians from your utility deem it to be safe. If you don’t have any experience with making a solar installation, it’s unlikely that you will get it right on the first, second or even third try.

If you want a grid-tie or a hybrid system, find a good installer. An installer can help with the permits, tell you about the available incentives, install the system correctly, and provide maintenance in the future.

7. Ordering delivery for a few panels from far away

The problem with transporting solar panels is that they sometimes break. The risk of damage by itself is small — from 1% to 5%. It increases with smaller orders and longer distances for a carrier, according to the A1 SolarStore RMA department.

Our advice: avoid ordering delivery if solar panels are in fulfillment centers that are further than 2,000-2,500 miles from you. Second, keep in mind that a bigger system with more panels is a safer bet. You can even add a couple of spare panels to your order as a possible replacement in the future. If you need less than 10 panels, it’s better to pick up the order yourself and drive it home safely.

8. Installing panels on an old roof

DIY solar installation on an old leaky roof is a grave mistake. Solar panels last for over 25 years. If your roof will have to be replaced in, say 10 years, you’ll also have to detach the panels from the old roof and put them on a new one. It will increase your expenses and put your solar system and your house at risk of damage.

When you hire a contractor to install a solar system, the first thing he’ll do is check the roof. If it’s weak, it has to be reinforced or replaced. Otherwise, the system is never going to get approved.

9. Adding batteries “just in case”

Solar batteries are an essential part of off-grid systems. They power your house on cloudy days and at night. In hybrid systems, batteries ensure an uninterrupted power supply. It can be important if power outages are too common or when you work from home and can’t risk losing power even for a few minutes. A hybrid inverter can also draw power from a battery in hours of peak demand when utility rates are higher and a solar system doesn’t produce enough.

While a battery bank makes your home more sustainable, it increases the cost of your solar system 1.5-2 times. It also makes the payback period longer. Think twice before adding energy storage. The worst idea would be to buy a battery and put it into the garage “for a rainy day”. Batteries are meant to be used: leaving them to rust shortens their lifespan, especially the lifespan of lead-acid batteries.

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10. Using small wires

Solar panels don’t come with a lot of wires and it’s up to you or your installer to choose them. It’s not a part of an installation where you should cut corners, but some still try. Remember: if you use a wire that is too small for your system, you risk starting a fire. The right gauge depends on the current and configuration of your system. Usually, you see 10 AWG cables in a solar system.

Vasilii Smirnov
Solar Installation Expert

Instead of getting the wire that just barely fits your system, buy thicker wires — preferably, the biggest size that works for your installation. Yes, it will be more expensive but the system will become more flexible. Maybe you’ll decide to add new panels, an inverter or batteries or rewire some things. Use stranded copper wires and not aluminum or copper-clad aluminum ones. Color code your wires! It makes it easy to read the system and it pleases the fire department if they come to visit.

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Andrey Gorichenski
Senior Editor

Andrey had been a news editor and freelance writer for a number of medias before joining A1SolarStore team. Climate change and its impact on people's lives has always been among his interests and it partially explains his degree in Philosophy and Ethics.

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