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AC Coupling Versus DC Coupling
Sep09

AC Coupling Versus DC Coupling

It is becoming more popular to install batteries with solar power systems on new installations and as retrofits. One of the questions to be answered when planning the battery installation is how will the battery system tie in with the solar. The answer will be either AC coupling or DC coupling. Solar panels produce DC power and inverters are used to convert this DC power to AC power. The terms AC coupling and DC coupling are used to describe where in the system the batteries are connected. An AC coupled system has the batteries tied into the AC output of a grid-tied solar inverter while a DC coupled system has the batteries tied in before the inverter where the DC power is flowing from the solar panels. Deciding which way to do your install, depends a lot on what other equipment you plan to use or what equipment is already in place if you are retrofitting. For example, if you are using microinverters, these microinverters are changing the DC power from the solar panel to AC power right at the solar panels themselves. Because the DC power from the solar panels is being converted immediately under each solar panel, it would be difficult to tap into so you would definitely go with the AC coupling option where you hook up your battery-based inverter to the AC output of the microinverter system. If you are working with a string inverter, then you have DC power coming from the solar array to the inverter and you can easily use it. There are few different ways to do DC coupling. One way would be to connect the output of the solar panels to a charge controller which charges the batteries and then you would have a battery-based inverter that changes that battery power to AC power. This is a very typical set-up for an off-grid system like the Outback SystemEdge Villa or Cabin Series packages. Another way to DC couple is to use an inverter like the SolarEdge StorEdge that will take the DC power from the solar panels and allocate it to the batteries or convert it to AC as needed. This gives the system a much higher efficiency than most other battery systems because every time the power is conditioned or converted, there is a small loss. If you run from solar panels to a charge controller to the batteries to the inverter. You will have a loss at the charge controller, a loss at the batteries and a loss at the inverter while the StorEdge system manages the power from the solar array in the most efficient way possible...

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Best Battery Types for Solar
Aug06

Best Battery Types for Solar

Installing batteries with solar is necessary on off-grid systems if you want power at night and also becoming more popular on grid-tied systems. Choosing what type of batteries to install can be a bit complicated so this article will cover the basics for you. The batteries that are most commonly used for solar are lead acid and lithium chemistries. No matter what, you will want to choose a “deep cycle” battery that is rated in amp hours (AH) and not a starting battery that is rated in cold-cranking amps (CCA). Car batteries are great for providing a lot of amps really fast to start a motor but they don’t do well with the long, slow draw of running the lights, TV and refrigerator in your home or off-grid cabin. If it is the zombie apocalypse and car batteries are all you can find, they will work but they aren’t the best choice for the application. Let’s start with lead acid batteries which can be broken down into the two basic types of flooded and sealed. Flooded batteries will be less expensive but they require maintenance and ventilation. When you purchase flooded batteries you are committing to adding distilled water to the batteries on a monthly basis. Without the added water, they can run dry which means they lose all charge and are likely to never hold a charge again. If you are not good at regular maintenance, buying these batteries can be a costly mistake. Even if you get the self-watering kit that does the work for you, you still need to maintain water in the reservoir and check to make sure the kit is correctly maintaining the water levels high enough. The ventilation requirements are also very important to consider because these batteries will vent hydrogen gas which is poisonous and flammable. Installing these batteries in your living space or anywhere there might be an open flame could have some nasty results. Sealed lead acid batteries are a little pricier but solve the unpleasant issues of the flooded batteries. You do not have to add water to them, they do not vent large amounts of poisonous, flammable gas and they can also be installed on their sides without worries about hazardous chemical leakage. The most available types of sealed batteries are gel and AGM. These are also often referred to as VRLA for Valve regulated lead acid batteries. Even within the categories of sealed and flooded lead acid batteries, there are different technologies being employed. For example, the Outback EnergyCell Non-Carbon batteries are a type of enhanced sealed lead acid batteries that have improved charging efficiency and a...

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Solar Panel Certifications Demystified
Jul17

Solar Panel Certifications Demystified

With dozens of brands of solar panels on the market, choosing which one to buy can be a conundrum. One of the things you that may help you navigate this field is to understand the various certifications that are given to solar panels and all the acronyms that go with them. UL (Underwriters Laboratories) is a global independent safety science company with more than a century of expertise innovating safety solutions. The first thing you need to know is the difference between a “standard” and a “certification”. Standards are design qualifications written by entities like Underwriters Laboratories (UL), International Electrotechnical Commission (IEC) and International Organization for Standardization (ISO) whose acronym makes better sense in other languages. When a solar panel receives a certification, it means that a recognized, approved lab has tested that solar panel to make sure it meets certain standards.  UL 1703 is the set of standards for safety for flat-plate PV Modules Let’s look at UL 1703 as an example. Officially published by Underwriters Laboratories, UL 1703 is the set of standards for safety for flat-plate PV Modules (aka the commonly used solar panels with the glass on the front). Cities and counties in the United States will only provide installation permits for systems that have solar panels that have the UL 1703 certification. This means that a manufacturer must send their solar panels to a Nationally Recognized Test Laboratory (NRTL) like Underwriters Laboratories, Intertek, TUV or CSA Group to have it tested. If it passes the test, that lab will provide a certification that the solar panel meets the UL 1703 standard. This process is also called UL listing and when the solar panel gets its official certification the manufacturer can say it is UL Listed. A UL Listed solar panel will have a special “mark” on its label from the NRTL that certified it. TÜV Rheinland is the leading provider of product testing and certifications for the worldwide marketplace.  While getting the UL 1703 Listing is a requirement, the solar panel manufacturers can step up their game and have the lab also test for other standards like IEC 61215 standards for durability and performance for standard monocrystalline and polycrystalline PV module. The IEC 61646 is a similar set of durability and performance standards for thin film PV modules. There are also very specific standards like IEC 61701 that includes salt mist corrosion tests (which you should look for if you are installing your solar panels on your beach house) or IEC 62716 that includes ammonia corrosion tests (in case you are installing your solar panels in agricultural environments).    PVEL is the independent lab for the...

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QCell Q.Peak DUO-G5 Advantage
Jan03

QCell Q.Peak DUO-G5 Advantage

Everyone knows solar panels are a good idea but are there certain ones that are a better idea than others? The answer is a resounding yes. Let’s take a look at the new QCell Q.Peak DUO-G5 as an example of a superior and award winning PV module. There are many innovations that have gone into improving the power output of the Q.PEAK DUO-G5 solar panels.  One is that the solar cells are interconnected with wires instead of flat ribbons on cells. These wires take up less surface area allowing the sunlight to hit more of the cell area. The innovative design also allows light reflected off the wires to be redirected back onto the module surface. This alone increases power production by 2.5%. Another design advantage was QCell’s choice to use six busbars on each cell. This decreases the space between busbars which means that the individual electrons have a shorter path to the busbar, decreasing losses to resistance. The extra busbars also allow better electron flow as there are more busbars to carry them. The six busbars result in a 1% increase in power production. Half-size solar cells in the Q.PEAK DUO G5 module increase power production by 3% by reducing the current which reduces the resistive losses within the cells. The half cell design also increases stability against pressure on the module, reducing the risk of the cell cracking. The chance of cracking is further reduced by the way the cells are cut with a smoother edge than typical solar cells. Plus, with the if a cell does crack, the six busbars mentioned above help mitigate the effects of the cracks causing resistive losses. Creating a much more stable design over all. This more stable design means a lower degradation rate of only .054% annually. QCell offers the guarantee of at least 85% production after 25 years on these innovative solar panels. The DUO-G5 PV modules are also different in their cell interconnection design. The upper and lower sections of the modules are connected in parallel instead of series. This results in higher power production when the module is partially shaded because the unshaded half of the module can still perform at 100%. Other technology that increases the performance of these solar panels is the Anti PID technology that reduces losses in wet climates. Hot-spot Protect (HSP) eliminates cells that have a high risk of creating hot spots from the production line keeping the modules hot spot free. As a matter of fact, all the solar cells on the production line are tracked with laser markings that are part of QCell’s TRA.Q traceable quality system. Anti LID...

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Solar Battery Showdown: Tesla Powerwall vs Blue Ion
Nov01

Solar Battery Showdown: Tesla Powerwall vs Blue Ion

If you’ve been looking to buy a battery to store renewable energy you might have noticed something strange — the shelves are nearly empty. The energy storage market, which up until recently had more than a half-dozen varieties to choose from, has gone through a bottleneck and drastically reduced in size, leaving only two competitors with any product left to sell. The reasons for the shortage are no mystery. With the portent of next year’s tariffs looming on the horizon and a narrowing window on government incentives, 2018 saw a rush to purchase energy storage units, such as the sonnenBatterie eco and LG Chem RESU, which were selling at record low prices. Now that the dust has begun to settle, the only two companies left standing are the Tesla Powerwall and the Blue Ion 2.0. The first might not come as a shock. The Tesla Powerwall is one product in a suite of Elon Musk’s renewable innovations, which enjoyed the advantage of first mover in the marketplace back in 2015. Tesla is also a larger company, and has the industrial infrastructure to create enough supply to satisfy market demand. The Blue Ion 2.0 was a bit later to the energy storage game. Reasons for its available stock most likely have to do with the fact that its founder, Henk Rogers, also happens to be the innovator of the pop-video game franchise Tetris, affording the company with enough startup capital to create more products than its competitors. Another possible reason for its availability is its price-point. Costing nearly twice the amount of a Powerwall, the Blue Ion 2.0 might seem more pricey at first glance. However, a side by side comparison of the two products reveals some noteworthy differences that might help justify the higher price tag for consumers shopping for the best deal.   BATTERY COMPOUNDS POWERWALL Powerwall runs on lithium manganese cobalt batteries, the same sort of stuff that’s used for power tools and powertrains on vehicles. Because the battery is made partially of manganese, the raw material cost is lower than other options as cobalt can be expensive. BLUE ION 2.0 Sony’s lithium ferrous phosphate batteries, which power the Blue Ion 2.0, are a high-end battery compound allowing for more efficient power storage. These batteries aren’t plagued by the same thermal runaway that traditional energy storage units are. The company claims its batteries are safer than Tesla’s, with the difference in material quality affecting all its other performance facets down the line. CHARGE POWERWALL It takes approximately 2 hours to charge a Powerwall using either peak sunlight or grid power. The battery has a leg up on...

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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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