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Aug 16 2018
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Does Solar Panel Temperature Coefficient Matter?

By How Does Solar Power Work on a House? Your Questions Answered No Comments

 

If you are trying to maximize the amount of energy that your solar panel system can generate, then your solar panel’s temperature coefficient is something that you want to be familiar with.

Your solar panel’s temperature coefficient has to do with the influence that the panel’s temperature has on its productivity. In this post, we will look at exactly what a solar panel’s temperature coefficient is and whether or not you should focus on it when planning your solar project.

Solar Panel Temperature Coefficient

The temperature of your solar panel has a direct effect on its ability to generate electricity. This has to do with the laws of thermodynamics and how heat limits any electronics ability to produce power.

For solar panels, this impact is reflected through the temperature coefficient, which is expressed as the percentage decrease in output for every 1-degree Celsius (°C) increase in temperature from 25°C (77°F). Solar panels are tested for their efficiency at 25°C, and that is why this is used as the reference point.

Most solar panels have a temperature coefficient of around -0.3% / °C to -0.5% / °C. For example, SunPower’s solar panels all have a temperature coefficient of -0.37% / °C.

What this means is that for every 1°C above 25°C, SunPower’s solar panels decrease in efficiency by 0.37%. So, if your panels are at 35°C (95°F) and have an overall efficiency of 17%, then their true efficiency at that temperature will be closer to 16.4%.

Temperature coefficients for top panels on Solar.com

Solar Manufacturer  Temperature Coefficient Range 
Q CELLS -0.42 to -0.37
Hyundai -0.45 to -0.41
LG -0.42 to -0.3
SunPower -0.38 to -0.29
Panasonic -0.3 to -0.29

Though this decrease might seem negligible, when you consider the fact that a solar panel can reach up to 65°C, this number can start to add up.

Does it Matter For Your Solar Project?

A solar panel’s temperature coefficient is not the only factor that influences a panel’s overall power output, but it is a good starting point for calculating a more realistic level of production for your specific setup.

When you are choosing the best solar panels for your home, you can think of how hot your panel may get and use that to estimate how efficient they will be on your rooftop. The good thing is that unless your solar panels are exposed to an exorbitant amount of heat, the decrease in efficiency will likely be negligible, even on a hot summer’s day.

If your roof is designed to absorb a massive amount of heat, and you are also living in a location that can see temperatures of 110°F or higher frequently throughout the summer, the loss will be greater, but still not so severe that it will make a long-term impact on your energy savings.

Having your solar panels on top of a heated vent will cause issues, so that is definitely something to watch out for while planning your solar panel array.

How to Minimize Solar Panel Efficiency Loss

Within the scope of the solar panel’s temperature coefficient, the primary way to mitigate loss in efficiency is through the reduction in the temperature of your solar panels. Here are some of the factors that influence the panel’s temperature:

  • The type of solar panel installation has a direct effect on the panel’s temperature. For example, if an angled, roof-mounted system is at 30°C, that same system, but mounted flat on the rooftop, maybe at 35°C.
  • Thin film solar panels have a lower temperature coefficient than traditional monocrystalline or polycrystalline panels. Thin film panels can see temperature coefficients closer to -0.2% / °C.
  • The material of your roof can have an impact on the solar panel’s temperature. Certain rooftops absorb more heat than others. Make sure to take into account your roof type when making your analysis.
Solar-Power-Power-Generation-Roof-Solar-System-2939551

Solar Temperature Coefficient is… Generally Insignificant

When you think of the long-term production goals for your solar panel system and then account for the losses that come from the panel’s temperature coefficient, the impact is quite insignificant for the majority of homeowners.

In most areas of the country, your solar panels will likely stay around 25-35°C throughout the majority of the year. The exception is with places that can reach extreme temperatures during the summer months, like Phoenix, Las Vegas, and many other cities, especially when considering the recent heat waves.

To get all of these details and more for your specific solar panel project, you can get started with our free service at Solar.com and talk with one of our personal energy advisors today!

Aug 10 2018
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The Pros and Cons of PACE Solar Financing

By Solar Loans: Financing Rates, Loan Terms, and More No Comments


You may have heard both good and bad things about PACE financing. Solar financing can be a good fit for some people, but not everyone. Here’s a deep dive into the advantages and things to be aware of with PACE.

What is PACE financing and where is it available?

Property Assessed Clean Energy (PACE) is a financing option for home energy improvements.

Not everyone who wants to make energy upgrades can afford a big upfront investment. For these people, PACE financing offers a new option. It allows homeowners to install clean energy systems (such as solar) or make other energy efficiency improvements with zero initial costs.

The PACE program is currently available in California, Missouri, and Florida for residential homes. The loan is paid off through an increase in property taxes. Here’s another article with a general overview of PACE.

Positive Aspects of PACE Financing for Homeowners

1. No Upfront Cost

zero-money-down-loan-1

PACE loans don’t require an initial investment, but the benefits start right away. Efficiency improvements can reduce monthly expenses. Clean energy generation, such as a solar panel system, can put a significant dent in energy bills or eliminate them. This is especially important in places like California and Florida, where energy costs are high.

2. Loan Stays with Property

Another positive aspect for homeowners is that they are not technically responsible for the loan should they decide to move. So, even if a homeowner installs energy upgrades and wants to move a year later, the loan stays with the property. Plus, the home is more valuable (thanks to those upgrades) and will likely sell for more money.

3. No Credit Check

This is very different from personal loans, second mortgages, home equity loans or other financing options. These typically require a down payment, or for the loan to be paid in full if the homeowner moves.

PACE loan assessments are based on property equity rather than credit score, employment history, monthly income, and debt. This could be a double-edged sword. It makes these loans easier to acquire, even if you don’t have a credit score in the 800s, but it could also spell trouble for a homeowner who doesn’t have a solid grasp on their finances.

What are some concerns with PACE financing?

1. Additional Property Taxes

taxes

While you might be able to ask for more with your home’s improvements, there’s also a chance you could have trouble selling it with additional property taxes attached.

2. Property Lien

Another possible selling roadblock is that a PACE loan is a first lien on the property. This means if a borrower (your potential buyer) can’t make the payments, the PACE lenders must be paid back before the mortgage lenders in the case of foreclosure or default, which is risky for lenders. This means mortgage companies might not lend the money to your potential buyer.

3. Complicated Structure

The major caution for homeowners is if they do not fully understand the details of the loan and can’t afford the increase in property taxes. If this happens and payments are missed, homeowners could be at risk of losing their homes.

There have been instances of contractors not clearly explaining the process and how the loan would be paid back. This lack of clarity is perhaps the most off-putting aspect of PACE financing. In the wrong hands, a PACE loan could be used by dishonest, or at least pushy, salespeople to manipulate homeowners into signing up for something they don’t fully understand and might not be able to afford.

How are PACE issues being solved?

This is not to say that customer experiences have been bad overall. In fact, most homeowners are happy with their PACE loans. DBRS, a credit rating agency, recently released data showing that foreclosure rates for houses with PACE loans are low (1.4 to 1.9 percent) compared to combined tax delinquency rates (1.9 to 2.3 percent).

As the system matures, the process is being improved. Two new laws were passed last year in California to protect homeowners.

The laws ensure that:

  1. Homeowners are fully aware of the stipulations, terms, and agreements in the loans.
  2. Loan providers perform due diligence to confirm that homeowners are financially able to repay the loan.

These laws hold PACE lenders to similar standards of transparency to those of traditional mortgage lenders. Hopefully, similar laws will be passed in other PACE states.

Pros and Cons of PACE Solar and Energy Financing

In summary, here are the main pros and cons of PACE:

Pros:

  • No upfront cost – the loan is repaid over 10 to 30 years through the property tax bill
  • Potentially reduces monthly utility expenses
  • Possibly eligible for energy tax credits and rebates
  • Loan passes onto next homeowner
  • House could sell for more money with improvements
  • No credit check

Cons:

  • The increased property tax bill
  • Often a higher interest rate than other energy efficiency mortgage alternatives
  • Lack of understanding or ability to pay an increase in property taxes could result in foreclosure
  • Many major mortgage lenders do not allow PACE financing
  • Possible difficulty in selling

In conclusion, do your homework!

  • Make sure you understand the details of what you’re signing up for
  • Shop around and get several quotes from different contractors and loan providers
  • Know the interest rate of the loan, project costs, fees, and payment terms
  • Be sure that you have the income to cover the increase in property taxes
  • Know yourself! Do you have the discipline to make the payments on time?

If you’re confident that you’ve found the best rate and understand your PACE loan, you could benefit. When in doubt, talk to your financial advisor or tax professional to get their insight into your unique situation.