What to Look for When Buying a Residential Solar Panel System

This guest post was written by the team at Infinite Energy. They have a list of 10 questions to ask a solar panel salesman before you commit to buying anything.  Mapawatt also has an introduction to Residential Solar PV installation in our Education section!

Solar panel systems – also known as solar photovoltaic systems – convert the natural energy from sunlight into a source of electricity. Today’s system designs work alongside utility company electrical grids to provide ongoing power supplies throughout the home.  Different product brands and system designs can vary greatly in quality and efficiency. Anyone considering installing a solar panel system in their home may want to take some time to get acquainted with the different types of products on the market. In the long run, being able to tell one from the other can mean the difference between buying a reliable energy source versus one that causes more problems than it’s worth.

Pros and Cons of Solar Panel Systems
A well-designed, properly installed solar power system can provide years of service with minimal maintenance involved. Ultimately, it’s the quality of the solar panels that determine how reliable and efficient a system will be. That being said, today’s solar panel technology still carries a mixed bag of pros and cons.

Solar panel systems can work for a variety of purposes, be it to power certain areas of a home or as the sole source of electrical power to a home.
•    Once installed and working properly, these systems allow homeowners to be energy independent

•    Solar power sources help to preserve the environment

•    Solar systems carry a high initial cost compared to conventional electrical providers

•    The cost savings value of installing a system takes a couple years to materialize before a system starts paying off

•    Regional difference in sunlight availability can hamper a system’s efficiency

Types of Solar Panels
Solar cells and solar panels make up the core components of a solar power system. Solar cells are the actual units that convert solar radiation into electricity whereas a solar panel contains an array of cells.
In general, any one solar panel will contain one of three types of cells –
•    Mono-crystalline
•    Poly-crystalline
•    Thin-Film

Much like the name implies, a single silicon crystal goes into the making a mono-crystalline cell. Actually, it’s only a slice of a crystal. When viewed inside a panel, these cells have a smooth texture. The intricate process involved with manufacturing each cell makes them the most expensive to produce; however, of the three types, mono-crystalline cells are the most efficient energy converters.Poly-crystalline cells are made from many crystals that sit inside a slice of a block of silicon. These cells have a sparkly appearance. They’re less expensive than mono-crystalline and also less efficient, energy-wise.  Thin-filmed cells are made from non-crystalline silicon materials. In effect, these cells consist of a thin-film of silicon spread across an underlying surface. As the least expensive and least efficient of the three types, their non-crystalline content allows for a flexible panel frame whereas the other two types require rigid frames.A great new innovation around colored solar panels is ideal for the more discerning consumer who may be put off by the aesthetics of blue and black solar panels, means panels can come in more ‘earth tones’ to match the existing roof.

Why Quality Matters
When shopping for a solar panel system, the importance of selecting quality panel materials cannot be overstated. Reputable manufacturers will be well-known names within the solar panel industry. Buying from a reputable manufacturer not only speaks to product quality, but also warranty support in case a system malfunctions. Likewise, solar panels imported from overseas may have little to no warranty support, especially in cases where the manufacturer goes out of business.  Poorly constructed solar panel systems tend to discolour and peel over time. System performance is also known to degrade and even breakdown with ongoing use. If you’re dealing with an overseas manufacturer, getting replacement panels often involves multiple mailings of panels overseas.  An accreditation seal or accreditation information is another thing to look for when selecting a solar panel system. Accredited product designs are backed by the Clean Energy Council or CEC.

Mapawatt Note: Quality is one reason we don't recommend building your own solar panels like the guys behind Earth4Energy or Power4Patriots do.  To get most incentives for solar you also need UL certification, and if you make your own panels you wont have this!

Solar Panel Outputs & Tolerances
Solar panel outputs and tolerances have to do with the amount of wattage a panel can generate from oncoming sunlight versus the amount it can vary in wattage output. The manufacturer lists output and tolerance amounts on product labels. Of course, the higher the output the better; but the amount of tolerance listed can affect a panel’s overall output in general.
Tolerances are listed in percentage amounts on the positive or negative side. For example, a panel with an output of 200 watts and a minus 10 per cent tolerance may actually only generate 180 watts on a regular basis. Another panel with an output of 180 watts and a plus 10 per cent tolerance will generate a minimum of 180 watts on up to 198 watts maximum. Just remember to always choose solar panels that have positive power tolerances.

Solar Inverters
Though solar panels make up the meat of a solar panel system, a system’s inverter device can greatly affect its overall cost-savings capacity as a whole. As many systems work along with a home’s utility grid, the inverter device converts the system’s DC electricity output into the AC electricity used in the home.
In cases where a system generates more than enough energy to power a home, the excess energy discharges into the utility system’s grid. When this happens, homeowners can actually receive cash rebates from their utility companies. Depending on the brand, efficiency levels for inverters can range anywhere from 89 to 96 per cent. In effect, the higher efficiency converters can earn homeowners hundreds of dollars more in rebates than the lower efficiency models.

Mounting Components
Solar panel systems rest on top of a mounting rack that attaches to the roof. A mounting rack must remain intact during periods of high winds, heavy rain, snow or whatever types of weather conditions ensue. For this reason, mounting rack materials should be professionally engineered to withstand these conditions for the life of the panel system. This means a quality mounting rack will consist of heavy-duty materials designed to withstand moisture, heat and pressure on an ongoing basis. This is something to watch out when a solar panel system is being installed.

Five Questions to Ask When Talking with a Salesperson
While there’s much to stay on the lookout for when shopping for solar panel systems, here are five key questions to ask when talking with a salesman (or woman) –
1.    Is the manufacturer of the panel a Tier 1 brand name?
2.    Does the solar panel manufacturer have an office presence in your country?
3.    What’s the inverter’s efficiency rating?
4.    What’s the solar panel’s efficiency rating?
5.    Does the system come with a professionally manufactured mounting rack?

Mapawatt Note: Also ask this person to give you a total life cycle cost analysis and payback information.  Make sure they include all state, federal, local incentives and any utility rebates, but make sure you qualify for all of them and DO NOT just take their word for it.  Get any guarantees in writing!

With this information in hand, you’ll easily be able to distinguish the good from the bad when it comes time to buy a solar panel system.


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"Are the panels manufactured on-site?" - I've never heard of anyone doing this. Is that a real thing? (Can I have more than 255 characters?) ;)

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