Run on Sun answers frequently asked questions about solar power

solar faq

Frequently Asked Questions About Solar

Technical questions about solar…

When people start to think about solar, many of their first questions are technical: how does solar work, is my home or business a good candidate for adding solar, and so forth. Here are our answers to those questions (terms in italics are further defined in the glossary below)…

How does a solar power system work?

Glad you asked! At its most basic, a solar power system consists of a collection of individual solar panels (collectively called an array) connected to one or more inverters, which are then connected to your building's electrical service.
Let's look at each of these components in more detail.

Solar Panels (also called solar modules) — convert sunlight into electrical power. Not all solar panels are alike; at Run on Sun we use LG solar panels for their superior performance and reliability. You can click here to learn more about why we use LG solar panels.

Like a sun-powered battery, solar panels only produce power when exposed to light, and the power that they produce is Direct Current (or DC). (Which just means that the leads coming from the panel have polarity, plus and minus, just like a battery.)

However, the electrical loads in your home or business — like lights, computers, TVs, pool pumps, air conditioners, etc. — all operate on Alternating Current (or AC) and that is where inverters come into the picture.

Inverters or Microinverters — the job of the inverter is to convert DC into AC. If multiple solar panels are connected to a single inverter, then that inverter is referred to as a string or central inverter. On the other hand, if each solar panel has its own inverter, that device is called a microinverter, and microinverters have a multitude of advantages over string inverters, including greater reliability, better performance in shady areas, and more sophisticated monitoring abilities.
You can click here to learn more about why we use Enphase Microinverters.

Interconnection — in order to actually power your loads, the output from the microinverters has got to get connected to your electrical service, and that can be a bit of a limiting factor. We will install a disconnect switch (so the local utility or the fire department can shut the system off if they need to in an emergency) along with a performance meter (so you can tell at a glance that your system is working) and then connect to a circuit breaker in your main electrical panel.

Due to something known as the 20% Rule, the size of your electrical service (measured in Amps) can limit how big a system we can install.

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Will a solar power system work on a cloudy day?

Yes, but not as efficiently as it would on a sunny day. The important thing to keep in mind is that solar panels produce power by converting sunlight (i.e, photons) into electricity (i.e., electrons). The more photons hitting the solar panel, the more electrons produced and thus, more power.

On a cloudy day, the amount of sunlight is reduced, so less power is produced. But not all cloudy days are alike. Some days, particularly in the late spring, have a high overcast layer that tends to burn off as the day wears on. The bright overcast might actually produce a substantial amount of light, even though there is no direct sunlight. In that case, your solar system would produce as much as 70% or more of its rated capacity.

On the other hand, dark, stormy days (the sort we rarely see around here) will greatly reduce the output of your solar system.

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How can I know if my house is a good candidate for solar?

This is an important question to ask since, sadly, not all homes are a good candidate for solar. Putting a solar system on a house that is "bad" for solar will only result in an underperforming system and an unhappy consumer.

To really answer the question, check out our blog post: Assessing My Home's Solar Potential: Step-by-Step.

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How is the solar power system attached to my roof?

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Will it leak?

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How long will a solar power system last?

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I heard that the technology is always improving — shouldn't I wait?

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Okay, I'm ready to start, how long will this take?

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Financial questions about solar…

Financing a solar power system is a key question for pretty much everyone before they can decide to go solar. How much does a solar power system cost? Should you buy it or (heavens forbid) lease it? Fear not, we've got you covered.

How much does a solar power system cost?

The short answer is, it varies - depending on the size of the system that you need, the nature of your roof, the condition of your electrical service, and so on. As a general proposition, larger systems benefit from economy of scale, whereas smaller systems are made more expensive by fixed costs that are not tied to system size (such as engineering or permitting). Steep roofs, tile roofs, or arrays far from the electrical main service panel will all cost more for the labor needed to build them.

There are two ways that the cost of systems are described: cost per Watt, and the Levelized Cost of Energy (LCOE). Sadly, cost per Watt is the most common way to talk about solar system costs, but it tends to be misleading since it is nothing more than the total system cost divided by the power (nameplate) rating of the system. So, a system with fifteen 300 Watt panels that sold for $18,000 would have a cost per Watt of $4.00 ($18,000 ÷ (15 * 300)). The problem with that calculation is that it tells you nothing about the quality of the components used (e.g., how well do those panels perform at temperature, or how efficient are the inverters being used?), nor does it take into consideration site factors that affect the yield of the system (such as shading or orientation). LCOE takes all of those factors into consideration and gives you a much better understanding of what a proposed system will actually save you compared to the energy you are buying from your utility.

All of that being said, we are currently installing residential systems that range from $3.90 to $4.75/Watt, with an LCOE of 9¢/kWh to 12¢/kWh.

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Should I buy or lease my solar power system?

We really do not like solar leases! Check out our Top 5 Reasons to Stay Away from that Solar Lease!

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Okay, leasing is out, but I cannot afford to pay cash. Are there any other options?

We know that not everyone can afford to pay cash, but you have lots of other (better) options, as we explain on our Solar Financing page.

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What about rebates and tax incentives, are they still available?

Yes and no. The really great news is that the federal, 30% solar tax credit has been extended! Rebates, on the other hand are an endangered species! You can read all about both on our Rebates and Tax Incentives page.

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What is net metering? I heard it's changing (Net Metering 2.0), will that affect me?

Net metering allows the owner of a solar power system to earn credits when their system generates more power than is needed by their home or business at that time. That credit is then used later when the building demands more power than the solar system is producing. And yes, it is changing (at least for SCE customers).
We've laid it all out in our post: Net Metering 2.0 Explained.

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How many bids should I get — and how do I compare them?

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Will installing a solar power system increase the value of my house? And if so, what will that do to my property taxes?

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Will the solar power system pay for itself? How long will that take?

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Environmental questions about solar…

Solar power, we are often told, is clean, renewable energy — but is it? Maybe you've seen those random posts on the Internet claiming that solar is actually dirty (it isn't), and all the environmental claims are false (they're not).
Let's set the record straight!

I heard that it takes more energy to create solar panels than they will ever produce. Is that true?

No, not even close. The National Renewable Energy Laboratory (NREL), which probably knows more about solar than anyone else, looked at this years ago and concluded that with solar panels that were only 12% efficient, the payback on energy occurred in just 4 years! The LG solar panels that we are installing today have efficiencies ranging from 18% to 20%+ so their payback is even faster. ( You can read the NREL analysis on solar energy payback here.)

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Even solar panels don't last forever. What happens to them at the end of their life?

Solar panels that are being taken out of service need to be properly handled, and not simply dumped into the nearest landfill. We are pleased that a growing number of solar panel manufacturers, including LG, are ramping up a recycling program for "retired" solar panels so that they can be disposed of in a responsible manner.

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Glossary

20% Rule — According to the National Electrical Code, the sum of the sources of current on a service panel cannot exceed 120% of the rating of the service panel bus bar. What does that mean? On a typical residential service rated at 200 Amps, both the bus and the main circuit breaker are rated at 200 Amps. Applying the 20% rule means that we can install a solar source breaker that is 20% of the bus rating, or 40 Amps, bringing the total of current sources to 240 Amps, or 120% of the bus rating. A recent development are so-called solar ready service panels which allow for higher solar connections, either by way of a dedicated connection that bypasses the bus, or by having a bus with a higher rating than the main breaker.

AC (or Alternating Current) — Electrical power where the polarity alternates (meaning that the flow of electrons reverses direction) so many times per second. In the United States AC powers operates at 60 Hertz (or cycles per second). Common appliances are designed to operate on AC.

Amp — An Amp is a measure of electrical current flow. Your electrical service is rated in Amps, with a 200 Amp service being the most common.

DC (or Direct Current) — Electrical power where the polarity is fixed, plus and minus, like with a battery or a solar panel.

Inverter — a device that converts (inverts) DC into AC power. Solar power systems use one or more inverters to convert the DC power from the solar panels to AC power for your home or business.

Levelized Cost of Energy (LCOE) — is the cost in $/kWh for the energy produced by your solar power system. It is calculated by adding up your final cost for the system over its lifetime (purchase price, financing charges (if any), maintenance costs (if any)) and dividing that by the total amount of energy that the system will produce over that same lifetime.

Loads — anything that requires electrical power to operate is considered a load. Electrical loads in a home include lights, computers, TVs, pool pumps, air conditioners, etc. The higher your total load the higher your electrical usage will be, and so to your bill!

Microinverter — a sophisticated form of inverter, designed to match up with one solar panel. Enphase microinverters are more reliable than conventional inverters, provide superior performance in shaded locations, and allow for comprehensive performance monitoring.