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Does Tilting Solar Panels Make Sense?
Oct08

Does Tilting Solar Panels Make Sense?

A solar power system will generate the most energy if you optimize the orientation of the solar panels. But, does that mean it worth it to tilt the solar panels on the roof? First, let’s talk about the best orientation for solar panels. In the northern hemisphere, you will get the best annual energy output if your solar panels are facing due south at a tilt angle just under your latitude. This means if you are in the southern part of the US at a latitude of 35, your system will give you the most kilowatt hours (kwh) if you face the panels south and tilt them at about 33 or 34 degrees from horizontal. Most roofs do not provide this ideal orientation. Your roof might south but the pitch is only 17 degrees. Your roof might not face south at all. It could also just be flat. Should you add hardware to tilt your solar panels to achieve that optimal production? Adding tilt legs to the solar racking will require more racking equipment and more labor to install it. Wind uplift loads are also a factor. When the solar panels are tilted, they are like a sail on your roof and more roof attachments would be required to ensure the solar panels stay put in gusty winds. All of this means higher upfront costs. Another consideration is that if the solar panels are tilted, the rows must be spread apart to avoid the solar panels in the front row shading the solar panels in the row behind it. Last but not least, there is the aesthetic factor. The purpose of solar is to save money not look pretty, but your system still shouldn’t be an eyesore. For the roof that is pitched at 17 degrees to the south, tilting the panels will generally not pay off. It would probably only gain about 5% annual output which will generally not be worth the added cost of the tilt hardware, extra roof attachments and labor. This is especially true if you are on a “time of use” or TOU electric rate pay more per kwh in the summer. If your solar panels are tilted at the lower 17 degree angle, they will actually produce more in the summer when the sun is higher in the sky to hit the lower tilted panels at a better angle. So, while you lose a little kwh over the period of the year, you will be generating more in the summer when kwh are worth more. Also, imagine for a moment how those tilted solar panels would look on your roof. Your neighbors would...

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What Solar Can and Can’t Do
Sep25

What Solar Can and Can’t Do

People have a lot of misconceptions about solar, often due to misleading marketing tactics by solar companies. If you are going solar, you should know the facts so you have realistic expectations. Solar can save you money. A standard grid-tied system feeds energy to your house so you don’t have to buy as much electricity from the electric company. But this is generally where it stops. Solar will not make extra money for you. Unless you are lucky enough to live in a place where you can sell Renewable Energy Credits (RECs), you are limited to saving what you normally spend on electricity. If you generate most of the electricity you use, you can reduce your electric bill to almost nothing. But if you generate more electricity than you use, you will get little or nothing back from the electric company for the excess kilowatt hours.   Solar can be used to provide backup power during a power outage, but this functionality typically costs extra and/or is very limited. The least expensive way to get back up power from solar is to use an SMA inverter that can be installed with a special power outlet that works during power outages. The limitations are that it only provides power when the sun is out and even then, it is only 1800 watts. So, if the power goes out at night or during a thunderstorm, that outlet won’t be much help until you have sun again. But, once you have sun, you will be able to power small devices, charge your phone or laptop and possibly even run your refrigerator. Beyond that special outlet, solar backup systems with batteries are available but they are pricey. They generally start around $7,000 for a small one. The more appliances you want to run during the power outage, the more the system will cost. It is usually cheaper and less limiting to purchase a backup generator that runs on diesel or propane. Solar can be used to run remote devices like well pumps and signal repeating towers. These systems can be set up two different ways. One way is to install solar directly to the device and when the sun is out, the device will work, when it is cloudy or dark, the device will not work. The other way is to install the solar with a battery system that stores the power when the sun is out so you can run the device any time. These types of systems are great options to run something that is too far away from the power grid. But, if everything you want to run is near...

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Chinese Vs American Solar Panels
Sep17

Chinese Vs American Solar Panels

Yes, you should buy solar panels, but… Should you buy solar panels that are made in America or solar panels that are made in China? We live in a modern world that operates on a global level. Things are made all over the world and solar panels are no exception to this. Even if a solar panel is labeled and marketed as “Made in the USA” it is very likely that the solar cells and/or other parts of the panel were made overseas. All the manufacturer must do for that “USA” label is assemble the foreign parts here in America. There are exceptions to this, but most solar cells are made in Asian countries, even in those panels that are assembled in the US. Does being made in Asia automatically mean the solar cell is of lesser quality. No, it doesn’t. The truth is that there are poor quality products being made in every country. History has shown that even some solar panels that were fully manufactured in the United States have had issues. But, fear not, there are also high quality products being made in every country.  There are top tier Chinese panels made by public companies with world class factories and clean rooms like Trina, Canadian Solar and JA Solar. Just as there are great solar panels made or assembled in America like Sunspark, SolarWorld and Gigawatt. Finding quality solar panels is more about brand than country of origin. We have a magic word we use in the solar industry, “bankability”. When a bank decides to offer leases on solar equipment, they have a lot at stake. They will end up owning hundreds if not thousands of systems, all with contracts that guarantee the end user a certain amount of production for up to 20 years. If the solar panels in these systems fail on a large scale, it will cost the bank a lot of money. So, before investing in a particular solar brand, the bank will do everything they can to ensure they are getting a quality, “bankable” product. This assurance includes third party engineering assessments of factories and products as well as evaluation of the manufacturing company’s longevity and ability to honor warranties in the long term. The banks have a lot of resources to put into these bankability studies. As an individual consumer, all you have to do is look at what brands the banks have chosen and use those on your own projects. There is also the consideration of price. Researching Chinese solar panels will bring up many news articles about tariffs being passed and the price hikes they may cause. In the end...

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New Solar Cell Technologies
Aug22

New Solar Cell Technologies

Over the years, we have seen the standard monocrystalline and polycrystalline PV modules increase in wattage per square foot, but they are getting close to the maximum possible efficiency on these typical solar cells. But manufacturers aren’t giving up, there are a few new up and coming technologies that will continue the progress of PV efficiency. Split cell technology uses the same solar material but cuts the cells in half. The new smaller solar cells have the same voltage as the original size cells, but they have half the amps. Putting 2 of these cells together gives you the same wattage as a single standard cell, but that wattage is a higher voltage and lower amperage. Power loss on conductors like the busbars inside a PV module is caused by voltage drop which is amps multiplied by resistance. Less amps means less voltage drop which means less power loss on the internal conductors. Voltage drop also causes heat build up so lower amps means the PV module is operating at lower temperatures, further increasing the efficiency. Overall, using split cell technology can increase solar panel power output by 5 to 8 watts per module. This lower operating temperature also increases the expected life span of the module as excessive heat leads to degradation. N-type solar cells are not new, but they are gaining popularity in the industry which until recently has been dominated by the p-type solar cells. Solar cells are made by “doping” silicon with very small amounts of either Boron to make the silicon more positively charged (p-type) or Phosphorus to make the silicon more negatively charged (n-type). The p-type solar cells are cheaper to make, but the n-type cells are more efficient. Adding to this, the Boron in the p-type cells causes an undesirable effect called Light Induced Degradation (LID). LID happens in the first few days and weeks that the p-type cell is exposed to sunlight and it can reduce its efficiency by 2%-3%. The n-type cells do not experience LID, so not only do they start at a higher efficiency than p-type and they maintain that efficiency over time. Another advantage of n-type cells is they are not as sensitive to impurities in the silicon base so manufacturers of n-type cells can use lower quality silicon without impacting the efficiency. Currently n-type PV modules are still more expensive than p-type, but many people are willing to pay for the higher efficiency, so the n-type is gaining in market share. Back contact (or rear contact) solar cells are another innovation coming to the forefront. A typical PV cell is made in a way that requires...

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How Many Solar Panels Do I Need to Charge my EV?
Aug03

How Many Solar Panels Do I Need to Charge my EV?

We are still miles away from being able to produce a practical, self-contained solar powered car but that does not mean you have to give up your dream of driving on sunshine. If you have an electric vehicle, you are halfway there. All you would need to add is some solar panels to your home charging station. Before we get into system sizing, many people have the idea that the solar electric vehicle charging station must be a stand-alone system, but that is not the best configuration. If the solar panels are only connected to the EV charger and you don’t drive anywhere that day, the solar power is wasted. The way to avoid that is to install a standard grid-tied system or a system with a SolarEdge grid-tied inverter with an integrated EV charger. With either of these options, the solar power produced when you don’t need to charge your car will be used to run other loads in your house or backfeed to the grid so it would never be wasted. So how many solar panels do you need to charge your EV? That depends on how much you drive. The average EV uses about .3 kwh per mile. This means if you average 50 miles per day, you would use about 15 kwh per day to keep it charged. With solar, it always best to talk about annual production because solar panels will always produce more energy in the long summer days than they will during the winter months. So let’s look at the annual usage for the car which is just the daily number multiplied by 365 days. In our example above, 15 kwh multiplied by 365 days is 5,475 kwh. That is the amount your solar would need to generate to off set the electricity used by the car annually. We have discussed system sizing in previous articles, but to give a short summary, you can start with PV Watts at https://pvwatts.nrel.gov/. Follow the prompts which start with entering your zip code so your production numbers will be location specific. It will also ask for a system size in kilowatts (kw). A good starting point is to take that kwh number you want to reach and divide it by 1,500. In our example above where you wanted to generate 5,475 kwh it would be 5,475/1,500 = 3.65 kw. Once you see the output on that system size, you can adjust the size up or down to get to the goal. You will also need to enter the tilt and Azimuth of the system. Tilt is just the angle from horizontal. If the system will...

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How Many Solar Panels Do I Need?
Jul25

How Many Solar Panels Do I Need?

Once you have chosen to go solar, the very important question arises. How many solar panels do I need? The first part of this is to figure out how many Watts of solar you need. This will depend on how much energy you want to generate. If you are shopping for a grid-tied system, you will find the answer in your electric bills. Every month, the electric company has tallied exactly how much energy (kiloWatt hours or kWh) you used so they could bill you for it. The meaning of that kWh figure and kW is commonly confused. The kWh is merely kW over time. For example: if 10 kW is consumed for 2 hours, that is 20 kWh. An analogy is kW is like a speedometer, indicating how much power is being consumed at one point in time. And kWh is like an odometer, indicating how much power has been consumed over time. All you have to do is look at the history of kWh usage on your paper electric bills or your online account with the power company. We recommend reviewing at least 12 months of electric history. You will definitely notice a difference in usage from winter to summer and basing your needs on just one month’s bill can be a big...

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