What Photovoltaic technology is right for me?

The quick and dirty on traditional PV technologies.

What does efficiency mean in a solar panel?

Solar panels manufacturers claim efficiencies ranging from 4% to over 22%.  Efficiency refers to the ability to take solar energy and turn it into usable electricity.  It's important to understand that a 200 watt solar panel that is 10% efficient will generate as much energy as a 200 watt solar panel that is 20% efficient.  The difference is the 10% solar panel will be twice as large.  Less efficient solar panels typically are less expensive than more efficient solar panels.  So, if you have ample room for solar panels then using more affordable and less efficient solar panels will increase your return on investment.  If ROI is your goal less efficient can be more effective.

Here are the three most common technologies:

 Monocrystalline silicon cells are single wafer cells that are the most efficient in converting solar energy to electricity (15-22%).  These cells tend to be more expensive.  The wafer is cut from cylindrical ingots, meaning the cell will not cover a whole square area on a panel, and will end up with gaps.

Multicrystalline silicon are cut from square ingots and are cheaper to produce, however they are less efficient than their monocrystalline cousins.  Multicrystalline (also known as poly crystalline) cells have a square shape allowing them to take up a whole square area on a solar panel without leaving any gaps.  The typical efficiency of multicrystalline cells are 14-19%.

 

Ribbon cells is a type of multicrystalline silicon cell that is manufactured from molten silicon.  This process reduces the waste of silicon, the most expensive part of a solar panel.  Ribbon cells are less efficient than monocrystalline and traditional multicrystalline cells with an efficiency of about 13-15%.

Do you need help figuring out which solar panels will be best for your application?  Contact an expert with proven experience - PurePoint Energy


Purepointenergy.com 
203.642.4105
info@purepointenergy.com

What happens to a solar panel in a wind storm?

Modern solar panels are built to withstand harsh conditions and most come with 20-25 year warranties. They can last much longer than that if properly installed, it is important to have a trained technician doing your installation. So how do I prevent solar panels from being damaged in high winds? You don’t have to do much. Most panels have a hard, clear plastic coating. Investing in a sturdy bracket and proper installation will pay off in the long run, and prevent the wind from having any effect on your solar array. Anything that hits the solar panel like hail or small tree limbs should bounce right off without doing any damage. The durability of PV solar has been proven in outer space NASA’s oldest solar panels are over 30 years old.

It’s February, it’s cold and there’s snow on my solar panels. What do I do?

Most people in the northeast don’t believe that solar is a viable option. Here at PurePoint Energy, we want to make you aware of the advantages and disadvantages of solar in the North Country. This month we’ll blog once a week about New England solar specific topics.

Having solar panels in the north with shorter days of sunlight, colder temperatures, and snowfall might seem like a bust; we aren’t saying that Portland, Maine will generate more solar power than Albuquerque, NM – but solar is still effective. PurePoint Energy would like to explain to you the facts about solar energy in the winter. These facts will answer your questions on how snow melts off your panels and how lower temperatures can actually increase power output.

The low down on snow.

If the snow completely covers your solar panel the panel will not create any energy. Your thinking: Do I need to go up on my roof and scrape it off, risking life and limb to make sure I’m getting a good return on my investment? No.

The solar panels will typically create enough heat to melt the snow off by mid afternoon.

This graph was found at http://www.solardave.com/

Snow is translucent and will heat your dark solar panels. This graph shows the result of snow melting from morning until about 1:00pm. Typically snow will fall off in one sheet (so make sure to be careful that neither you nor your car is directly underneath). This is apparent in the graph above with the sharp increase in energy production. So when it snows be patient, just wait for the snow to melt off and think of the upside.

Yes, there is an upside:

Temperature can drastically effect the energy production of a panel, for those of us that live in the north that’s a good thing. Colder temperatures increase the efficiency of a panel while warmer temperatures decrease efficiency.

  This is a spec sheet from a GE PVp-200-M solar panel.

 

For example: this solar panel looses ½ a percent of efficiency for every 1°C increase. So if we look at the first week in February, the high in Miami FL will be 24°C while in Norwalk, CT (Pure Point Energy’s Headquarters) the high for the week will be 4°C. That’s a difference in 20°C, or 10% more power generated by your solar panels at solar noon.

So even though we live in the north we can still make solar work for us.