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Answers to common questions about solar power

Answers to common questions about solar power
You've got questions, we've got answers. We've organized these FAQs by topic. If you don't see the answer you're looking for, please contact us toll-free at 866-GET-SOLAR (866-458-7652) or viaemail.

Photovoltaic Technology

Q: How do photovoltaics work?
A: Here's a short answer: Sunlight on photovoltaic modules produces direct current (DC) electricity which is converted to alternating current (AC) by a device called an inverter, which is then wired into your main service panel where it feeds your internal power grid. For more details, click here.

Q: I know people that have broken solar panels for their homes. How is this different and why is this more reliable?
A: Good question! The broken solar panels you're referring to are likely solar hot water panels, in many cases date back to President Carter-era tax credits, which President Reagan promptly repealed early in his first term. The resulting slack in demand put many solar hot water panel manufacturers out of business, leaving an unfortunate legacy. Photovoltaic technology is completely different, is for the purposes of making electricity, not heating water, and has a 50+year history of reliable performance. Click here for more on the history of PV technology.

Q: How long will PV modules last?
A: Based on manufacturers' in-field experience and reliability testing, PV modules will probably last longer, and are more reliable than just about any other capital investment for your business. In 2003, BP Solar published the results of their analysis of warranty claims and reported that of more than two million modules in service over nearly ten years, approximately one-tenth of one percent were reported faulty, noting "this represents one module failure for every 4,200 module-years of operation." Put another way, if your system has one thousand modules, you may experience the failure of ten modules in 40 years.

Q: Are there any major advances in technology on the horizon that I should hold out for? (e.g., plastics, nano, thin film, etc.)
A: Unlike the other major use of silicon – computer chips – photovoltaic technology is not subject to Moore's Law. According to the National Renewable Energy Laboratories, the rate of improvement of achievements in efficiency for crystalline solar cells is less than 1% per year since 1970. Additionally, today’s commercially-available PV products’ efficiency levels were achieved in the laboratory anywhere from 15-20 years ago, indicating the long lag between research gains and commercial product introduction. Net, waiting for a magic solar bullet will probably mean waiting a long time, and paying a lot for electricity in the interim.

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System Design

Q: How do I (we/you) determine how large a system I'll need?
A: The size of the system is usually directly proportional to the amount of power you use. As part of the proposal process Sunlight Electric will perform a site assessment, analyze at least twelve months' worth of utility statements, and raise the question of near-term (3-5 year) expansion and business plans. With that information, taking into account the specifications and limitations of the components, Sunlight Electric will present recommendations for your input and feedback the goal of making sure you feel the ultimate path chosen is ideal.

Q: Roof-mounted or ground-mounted?
A: It depends. Roof-mounted tends to be less expensive as they require no support structures and are most often not visible to passersby. On the other hand, ground-mounted systems can usually be oriented and tilted to optimize production. Through understanding your business and your needs, Sunlight Electric will present a solution that optimizes for your business and your needs.

Q: What happens on dark/cloudy days?
A: Unlike the early days of solar power when systems had to be sized for peak loads, a grid-connected PV system seamlessly switches to draw from the utility grid when needed. As such, Sunlight Electric uses an annual production target, averaging out sunnier days with cloudy days.

Q: Do I need batteries?
A: Is back-up power critical to your business? For most businesses, the answer is “no” and if you don't have a back-up solution today, an ordinary grid-connected PV system will leave you in the same position. However, if you require back-up power or are looking to upgrade your business's disaster preparedness, Sunlight Electric can design a battery storage solution for your PV system to automatically switchover in the event of a power outage. Most customers inquire about batteries and ultimately choose to do without based on cost.

Q: I have plans for expansion. Can I plan for this now?
A: We frequently take into account future growth plans when designing your system. The choice of inverter can be influenced by near-term expectations about power usage and in some cases it may make sense to include excess capacity now and simply add more modules later. We'll discuss this with you and explore a variety of options to meet your needs now and in the future.

Q: What will this do to my roof?
Sunlight Electric PV systems typically weigh no more than 3-4 lbs/sq ft, and most flat roofs have a 20# per sq ft 'dead load' capacity so array weight on the roof is rarely an issue. We can also design a solution to be completely non-penetrating if your municipality accepts our engineering testing documentation, as many have.

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Products

Q: I hear XXXXXXX's modules are the most efficient. Wouldn't those be the best choice?
There are some considerable performance differences between manufacturer's products and often there are differences within a given manufacturer's product line. As you might expect, greater efficiency carries a higher price. SunPower makes the highest efficiency solar modules on the market and Sunlight Electric has been a SunPower dealer since 2008. In every case, Sunlight Electric seeks to design the most cost-effective solution, maximizing your long-term return on investment while minimizing the initial investment and therefore will provide an assessment of the relative merits of all major solar module technologies.

Q: I hear XXXXXXX's modules are the cheapest. Wouldn't those be the best choice?
As with most products, you get what you pay for. Given the 25-year performance warranties solar module manufacturers’ offer, Sunlight Electric screens module manufacturers not only for product quality and performance, but also for long-term financial viability since a 25-year warranty from a company that went out of business creates a risk that can overwhelm and potential savings from using discount modules. We typically choose only diversified manufacturers who can weather the ups and downs of the business cycle to ensure long-term warranty coverage is maintained. In fact, many so-called “Tier One” manufacturers do not pass our financial health screen due to limited track record, lack of consistent profitability, or opaque financial data.

Q: I've never heard of the companies that make inverters (e.g., SMA, ABB, Schneider, etc.). How can I trust them?
A: Sunlight Electric sources inverters from only the largest, best-capitalized manufacturers for quality, longevity, and long-term financial viability.

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Subsidies & Economics

Q: How much do these systems cost and how much money will I save each year? How long will it take to pay back my investment?)
A: The size of the system is the largest determinant of the price, and the savings rise accordingly. In most cases, the payback period for the investment in a photovoltaic system is roughly 5 years with internal rates of return ranging from 15% to 25%, depending on the avoided cost of energy and the site-specific design and resulting costs.

Q: What subsidies are available?
A: Commercial solar buyers benefit from a 30% federal tax credit (though 2019) and accelerated federal depreciation. Combined, these tax benefits typically defray as much as 70% of the out-of-pocket cost of solar. Sunlight Electric will give you the most current information and include that in your proposal with detailed pro forma cash flow statements for a variety of appropriate financing mechanisms. For more details on currently-available solar subsidies.

Q: Is financing available?
A: The best source of financing is usually the bank, finance company, or mortgage company with whom you currently work. If you like, we're happy to make arrangements with a number of independent solar finance partners we've worked with on other projects.

Q: What's the impact on my property taxes?
A: Photovoltaic systems are exempt from property taxes in California.

Q: We don't own the property on/in which we operate. Can we still go solar?
A: Yes, it's relatively commonplace for property owners to allow their tenants to make improvements in their facilities and we have many customers who are tenants with long-term leases.

Q: Since the return on investment hinges on selling power to my utility, how can I be confident this will be accurately accounted for?
A: The power you generate is metered by your inverter and the utility meter tracks power in both directions – both power you buy and power you sell back to the utility. Plus, you can track your production and the power you export via our online monitoring software. Finally, you'll receive a monthly statement from your utility company. All these provide ample reassurance that the accounting will be done, as it has been done for the over 100,000 interconnected photovoltaic systems all across California.

Q: What are the critical assumptions for modeling ROI?
A: The key drivers are avoided cost of power no longer purchased, the site-specific system design and cost, and the value of the state and Federal subsidies.

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Installation

Q: Will a roof-mounted system void my roofer's warranty?
A: We frequently coordinate our work with roofers to ensure warranties remain in force and the PV system installation also comes with a 10-year warranty that includes roof integrity.

Q: My building's roof needs replacing soon. Does it make sense to integrate the installations?
A: Yes. If you're planning to replace your roof in the next few years, it may make sense to move that up and install the PV system at the same time as the new roof is going on.

Q: What if my roof needs repair after the PV system is installed?
A: Spot repairs are easily accommodated as any since module is secured with only four bolts. Non-penetrating ballasted systems can also easily be moved to accommodate repairs.

Q: What kind of county/city permits will I need?
A: We always need an electrical permit from the city or county and some require a building permit as well. Sunlight Electric and our licensed installers will handle all of this, from applications to inspections.

Q: How long will my installation take?
A: This depends mostly on the size of the system, site access, and the distance between the array(s) and the main electrical service. In general, figure one week for each two hundred modules to be installed.

Q: Will installation interfere with my normal business operations?
A: Most work is conducted on the site of the array installation (roof or ground) so your operations will likely not be impacted. We coordinate our efforts with your team, from deliveries, securing equipment, to crane usage and we always schedule site material deliveries and other electrical work that could impact operations well in advance and always get advance sign-off on these activities from our customers.

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Ownership

Q: What are the maintenance procedures and costs?
A: Solar PV systems are solid-state technology, have no moving parts and require no maintenance beyond cleaning, which can typically be done with a garden hose. Most systems should be cleaned once or twice a year, concentrated in the dry season. Systems in agricultural areas will likely require 2-3 cleaning per year.

Inverters are also solid-state and require little to no maintenance beyond regularly checking the cooling fan outlets and cleaning when necessary. Mounting hardware is either aluminum or stainless steel or high-quality ASA resin (same as car side mirrors) and is rust-proof.

Q: Does cleaning the modules require any special expertise or equipment?
A: No special skills or equipment needed. At the completion of each installation, we’ll provide our cleaning guidebook and train your team on how to clean your solar panels. We can also offer scheduled cleaning programs and referrals third-party service providers who can clean for a modest charge.

Q: What parts will break first?
A: The inverter(s), which typically have a useful life of 15-20 years, will be the first thing to fail.

Q: What about rust and oxidization?
A: All hardware is made for outdoor use and is made of either rust-proof stainless or galvanized steel, aluminum or high-grade outdoor-rated plastic.

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Myths/Misperceptions

Q: Someone told me that the energy required to make PV panels is greater than they will every produce. True?
A: Glad you asked -- we've heard this one before. Numerous studies indicate it takes 2-3 years to generate as much power as is required to manufacture photovoltaic modules, and the Environmental Working Group's Green Energy Guide reports an energy return on investment for photovoltaics of 9-to-1, greater than most other electricity sources (i.e., coal: < 8:1, wind: 5:1, nuclear: <5:1, biomass: 3:1).

Q: I hear manufacturing PV panels creates toxic by-products and waste. True?
A: Another good question. There's less documentation on this than the energy return on investment question, suggesting it's probably not an issue, but the Environmental Working Group's Green Energy Guide reports the manufacturing and operation of photovoltaics creates far less emissions than any other source of electricity analyzed.

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Photovoltaic Technology
System Design
Products
Subsidies & Economics
Installation
Ownership
Myths/Misperceptions

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