John Smith is a homeowner in California looking to reduce his electric bill by going solar and he decided to call an installation company that he found on the internet.

The next day, a rep from XYZ Solar came out to his house and, after looking at his electric bill, told John that he would need an 8.5kW PV system to offset 100% of his past 12-month usage.

The economics made sense and shortly thereafter the rep walked around to the side of the house and snapped a couple of photos of the main service panel.

We covered Main Panel Upgrades in Pick My Solar LIVE! Patrick and Kyle share a full look into how to determine if a breaker upgrade is necessary for your solar project.

Two days later, John received a call from the same rep and was told that, unfortunately, the main panel upgrade would be required, adding an additional $2,000 to the cost of the project.

When the rep tried to explain why an upgrade would be necessary, the explanation made much less sense. In fact, it made no sense at all when the rep told John, “Normally, an upgrade would not be necessary, but your main service panel is center-fed, which is why an upgrade – in your case – is required”.

In many cases, a homeowner could be spared the $2K expense if the installation company were to perform a simple load calculation to determine whether or not de-rating the main breaker is possible, safe, and passable by city inspectors.

For John’s project, a 7600W string inverter is being proposed by the installation company – a good choice, and the spec sheet shows 40 amps of back-feed protection is required by the main service panel in order for this inverter to be connected. Now, John looks at the sticker on the inside door of his main service panel box, which says 200A. The main breaker switch also says 200A.

But how can John figure out the amount of back-feed protection available on his main service panel?

A simple formula is as follows: 200A buss bar (as shown on the sticker) X 120% = 240. Then, take 240 minus 200 (main breaker) = 40A. Since we need 40A of back-feed protection, we are good to go.

Check out this video to understand the amps of your panel box

Project aspects like this might sound slightly complicated, which was why Solar was founded – to ensure the consumer is protected when technical aspects of projects are laid out.

We play the role of homeowner’s advocate to make sure there’s always an unbiased solar expert to bounce questions off of.

If you are considering installing a solar system at your home or place of business, then you have many factors to consider. The paramount factor to many buyers is which solar panels (referred to as ‘modules’ in the industry) to choose. During your solar research, you will undoubtedly come across two solar module manufacturers: SunPower and LG. Both are widely recognized as high-end modules with SunPower leading the way. So which should you choose?

Cost

SunPower is more expensive. Partnered with roughly 200 solar installation companies across the nation, Solar.com sees SunPower pricing to be $0.57 per Watt higher than LG. This equates to a $3,420 on the total cost for an average sized residential solar system (6,000 Watts). This is a significant cost increase for most homeowners or business owners so it’s important to understand what differentiates the two brands and their products.

Efficiency & Nominal Power

Solar module efficiency refers to the portion of energy in the form of sunlight that can be converted via photovoltaics into electricity. SunPower modules achieve a high of 22.2% with an average of 20.6%, while LG’s current products can achieve 19.5% with an average of 18.3% on the efficiency scale.

Nominal power, rated in DC Watts, is an important characteristic of a solar module to consider. SunPower’s modules range from 327W – 360W, while LG’s residential modules ranges from 275W – 320W. LG does currently offer modules as high as 370W, but these are larger in size and are typically used for commercial solar projects. Nominal power is significant because if you are a homeowner who needs a 6,000 W system to offset your electricity consumption from the Utility, you would need 17 modules with SunPower or 19 modules with LG.

Depending on how much available space you have on your roof, this may impact your decision. Also, if you plan to increase your energy consumption in the future (e.g. plan to have kids, want to get an Electric Vehicle, etc.) you may want to choose SunPower modules so you have enough space to install more modules in the future (if roof space is a constraint).

Degradation

Degradation is another characteristic of modules and it refers to their power decline over time. Most manufacturers guarantee their modules to degrade no more than 0.7% each year for 25 years. At 0.25%, SunPower’s X Series has the lowest degradation rates of any manufacturer. LG is better than average at 0.6%. After 25 years, a SunPower solar system is guaranteed to produce 92% of the electricity that it did at the time of installation while an LG solar system is guaranteed to produce 83.6%. The difference here may seem insignificant, but over the course of 25 years, this can add up.

Aesthetics

Homeowners and business owners who are concerned with aesthetics, often choose an “all black” module with a black frame and black back sheet. SunPower and LG both offer this style. However, SunPower’s all black module has a nominal power rating of 335 Watts, while LG ‘s is rated at 305 Watts. With a similar appearance, your decision to choose SunPower or LG should rely more on available roof space and the solar system size you need.

Warranty and Bankability

These two factors are closely related and should be discussed together. Warranties provide both security and peace of mind to consumers, but if the manufacturer goes belly up, their warranty is meaningless. SunPower leads the industry with their 25/25/25 warranty, covering performance, product defects, and labor. LG covers the performance for 25 years and any product defects and labor costs for 12 years. If you have a defective solar module after 18 years, SunPower will send someone out to replace the module at no cost to you, however, LG will not. That said, If you chose an installation company that has a 25-year bumper-to-bumper workmanship warranty, then this is a moot point.

Now let’s take a look at the bankability of these two companies. Everyone has heard of LG. You may have a microwave, television, or refrigerator in your home that is made by LG Electronics. Unless you’ve looked into going solar, you likely have not heard of SunPower. Looking at the NASDAQ, SunPower’s stock price has steadily declined over the past year from $24 in March 2016 to roughly $8 today. LG stock prices have remained steady during that time period and have even risen slightly from $10 to $12. The solar industry is still relatively immature and changes in policy and advancements in technologies can have a direct impact on manufacturers. Soon after Congress extended the 30% federal investment tax credit for solar in December 2015, SunPower announced 1,200 layoffs and shares quickly dropped over 30% in trading. The diverse portfolio of LG protects itself from any changes specific to the solar industry, arguably, making them a more stable and bankable company.

Coming Soon from LG

LG has developed residential solar modules that seem to truly rival SunPower. The LG NeON® R modules appear to close the gap and even exceed many of the advantages that SunPower currently has over other products. If LG keeps the price point near the current modules they offer, homeowners and business owners may have a tough time justifying SunPower’s higher cost.

Going solar can be a daunting task to many as there are many things to consider. The solar modules you choose are an important consideration, but many other factors deserve more attention. Contact Solar.com who will analyze everything for you. If you’re ready to go solar and deciding between SunPower and LG is the last piece of the puzzle, Solar.com will find you the best bids for both brands in your area so you can make an informed decision. 

Have more questions or want to speak to someone regarding the best solar panels for your home? Please call (888) 454-9979. 

Still, want to do more research? Continue reading our blog here or click here to see your custom savings estimate. 

This article was updated on October 20th, 2017 to reflect SunPower’s latest degradation rate and power warranty.