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Choosing Batteries for Solar
Feb18

Choosing Batteries for Solar

There has been a lot of buzz in the solar industry about batteries. They are necessary for most off grid solar applications and becoming an add-on trend for grid-tied systems. You can read our article “Should You Add Batteries to Your Solar” to find out if installing batteries is a good idea for you. If you do decide you want them, the next step is to choose which batteries are right for you.  One of the factors involved in this decision is what other equipment you will be using. From a technical standpoint, the inverter you will use will determine the required battery voltage. For example, the Outback Radian inverters typically need a 48 volt battery bank which means you are likely going to buy batteries that are 2, 6 or 12 volt and wire them in series to get a 48 volt battery bank. On the other hand, SolarEdge inverters require a 300 volt battery so you will typically use something like the LG Chem batteries that output that higher voltage.  From an install perspective, there are advantages to the higher voltage batteries. The higher voltage means lower amperage so the wires from the batteries to the inverter can be smaller and can be run much longer distances. Typically, with a 48 volt battery bank, your wires are going to be 2/0 AWG or 4/0 AWG and less than 10 feet. With the 300 volt batteries, it would be 10 AWG or 8 AWG and a 50 distance is no problem.  Battery ventilation requirements are also something to consider as this varies with the different battery chemistries. The least expensive batteries are flooded lead acid chemistry. They vent hydrogen gas and must be installed in a well ventilated area away from sparks or flames and separated from living spaces. Other battery chemistries, like sealed lead acid and lithium, do not vent any nasty gases and are much more flexible on where they can be installed. The physical space needed for batteries is also a consideration. If you have room for a lot of batteries on the floor or large battery cabinets or shelving, you can get the batteries that are shaped like boxes and spread them out on the floor, install them on sturdy shelves or put them in cabinets that are designed for batteries. They make almost all battery chemistries in this box shaped style. If you don’t have a lot of space, you should consider the lithium batteries like the LG Chem that are a slim box that hangs neatly on the wall. This will be the more expensive option and you won’t get as much...

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Service Panel Upgrades for Large Enphase Systems
Jan27

Service Panel Upgrades for Large Enphase Systems

When planning your grid-tie solar installation you have to consider some things about your main service panel because that is where you are going to make your connection to the grid. The larger the solar system, the more likely it is that you will have to make some adjustments or upgrades to your service panel in order for the installation to be code compliant. There are also a few tricks that may get you out of doing that extra work. First, let’s discuss 2017 NEC 705.12(B)(2)(b) and 705.12(B)(2)(d). These code sections are the reasons why you may have to alter your main service panel in order to install your solar. These code sections describe what is lovingly referred to by solar installers as the 120% rule. The 120% rule says that for load side interconnections, 125% of the maximum solar output plus the rating of your main service breaker must be less than or equal to 120% of the busbar rating. This is true for all solar installations but we are going to do the math with the popular Enphase microinverters so we can get very specific. Example 1: You are installing 16 Enphase IQ7 microinverters which output 1 amp each. Your total maximum solar output would be 16 amps.125% of your maximum solar output would be 16 x 1.25 = 20 amps.Your main service breaker is 100 amps and your main service panel busbar is 100 amps.120% of the busbar would be 100 x 1.2 = 120 amps.Your main breaker plus 125% of the solar output would be 100 + 20 = 120 amps.120 amps is equal to 120 amps so you are just barely okay to install as is. Example 2:You are installing 45 Enphase IQ7 microinverters which output 1 amp each. Your total maximum solar output would be 45 amps.125% of your maximum solar output would be 45 x 1.25 = 56.25 amps.Your main service breaker is 200 amps and your main service panel busbar is 200 amps.120% of the busbar would be 200 x 1.2 = 240 amps.Your main breaker plus 125% of the solar output would be 200 + 56.25 = 256.25 amps.256.25 amps is not less than or equal to 240 amps so you can’t do a load side connection like this. If example 2 is your situation, let’s review your options. You can de-rate your main service breaker to 175 amps. This changes the math to 175 + 56.25 = 231.25 amps which is less than 240 so you are good to go as long as you can do some load calculations to prove that your house will be okay with only...

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Where Should You Install Solar?
Jan21

Where Should You Install Solar?

Everyone knows solar panels can save you money, but where should they go?  First, let’s discuss location on a larger scale. There is no place in the United States where solar wouldn’t work. You might think you it is too rainy, too cold or you live too far north and don’t get enough sun but let’s drop those excuses.  There is no location that gets too much rain. Even in Seattle with 226 cloudy days and 38 inches of rainfall per year gets enough sun for solar panels to be worthwhile because solar panels will still produce electricity on cloudy days, just not as much as they would on sunny days.  Too far north is not a problem, but there are things to consider. Unless you are at the equator, solar is going to produce more power and in summer and less power in winter because of the angle of the sun and the amount of daylight hours. The further north you go, the more extreme this is. In Alaska, solar works great in the summer but it won’t do much in the winter. In the continental US, you will still get solar power in the winter and with most grid-tied systems you would be on yearly net metering billing with your electric company so it doesn’t really matter what month the power was produced. Many people think solar panels don’t work when in the cold, but they actually work better when it’s cold out. Cold temperatures can increase solar production by as much as 10%. The other side of that is really hot temperatures will lower production by 10% but that still means your getting a lot of free power from the sun, so don’t sweat it. So now that you know you are in the right geographic location for solar, let’s talk about where to install solar panels on a smaller scale. If you have a few acres of land you will probably have plenty of room for a ground mounted solar system. Even a half acre yard might have enough space that isn’t shaded by the house, depending on the layout. Ground mounts have advantages in that they are easier and safer to install (no lugging solar panels to the roof or worries about fall hazards) and you also have more options on orientation. You can check out our article on ground mounts vs roof mounts to get a better understanding of whether or not ground mounted solar is right for you. If your yard is small, then your roof will be the best place for the solar panels. Solar panels facing south will produce the...

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How to Pass a Solar Inspection
Jan07

How to Pass a Solar Inspection

If you are going to install your own solar, you are going to have to deal with the city or county inspector. This can be easy or it can create a lot of extra work after you thought you were done with your installation. Some of it depends on the inspector, but most of it depends on you. Let’s talk about the things you can do to make the solar inspection a breeze. First, do your installation correctly. You would think this goes without saying, but it often happens that corners are cut during the installation or substitutions are made for equipment that you don’t have on hand.  Also, there are times when you may not know what “correct” is. One of the more confusing parts of installing solar is grounding. To make this aspect even more difficult, different cities and counties often have different rules. You should read our previous article that gives an overview of grounding for solar but just to cover some basics, make sure your solar racking is grounded per the racking manufacturer’s instructions and make any splices in your grounding conductor with permanent crimps instead of using wire nuts.  You will also want to know ahead of time what the city or county is expecting for your existing house grounding. The rules have changed over time and the older your home is, the more likely it is that you will have to upgrade or modify the existing grounding system. For example, you may have to add a second grounding rod that wasn’t required when your house was built, but now the inspector wants to see it. Your best bet is to ask questions about this at your local building department before you schedule your inspection so that you can have any necessary modifications completed before the inspector arrives. The other thing you should do before the inspection is document any “as built” changes to your installation. For example, the plans that were approved by the building department show the solar panel layout but you had to make a change to the layout when installing because there was a roof vent in the way. Sometimes inspectors can approve these “as built” changes on the fly, but more often than not, the inspector will want these changes submitted to the building department and approved so that the system they are inspecting matches the approved plans exactly. On the day of inspection, make sure you are there to walk through the system with the inspector. Before the inspection appointment, take the covers off all the equipment so the inspector can see the wiring inside. Set up a...

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DIY Solar Monitoring
Jan02

DIY Solar Monitoring

So you have all the solar panels installed on your roof, your wiring is completed and the system is powered on but are you done yet? No, there is one more important thing to do. You have to hook up the PV system monitoring.    You solar will work without monitoring but the monitoring is how you know it is still working. In general, solar doesn’t require a lot of maintenance, but once in a while, things go wrong. A breaker could trip, someone could turn off the solar disconnect by mistake, an inverter can have a fault that prevents it from working until it is reset, a squirrel could chew through a wire on the roof – you get the idea. Without a monitoring system, you may not realize you have a problem until you get an electric bill as high as they used to be before you installed the solar. With monitoring, you can catch a problem and fix it well before you rack up a high bill with the electric company. To install the monitoring, the first step is to get your solar hooked up to the internet. Fortunately, most solar monitoring is pretty easy to install these days so you don’t have to be an IT genius to accomplish this. When purchasing your inverter (or microinverter) equipment make sure the distributor knows you intend to install the monitoring so they can make sure they include all the parts you will need. These parts will also include instructions and if they don’t you can easily find them on the manufacturer’s website.  The one thing you will want to do during the installation process is capture the serial numbers of each microinverter or DC optimizer in your system before you install the solar panels over them. They usually have stickers that you can pull off and stick to the layout in your solar plans (or any piece of paper). This creates a map so that if one of these devices fails, you know right where it is. Without this map, you can spend a lot of time hunting through your system trying to find the optimizer or microinverter has failed. The rest of the magic happens after the system is installed. One of the biggest challenges can be that your wifi signal is too weak at the inverter or system monitor location. This can be easily solved by purchasing a wifi extender and installing it between the router and solar device. Many of these just plug into any outlet between the router and the solar monitoring device and boost the wifi signal so that it will be strong...

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Choosing Roof Attachments for Solar
Dec17

Choosing Roof Attachments for Solar

Choosing equipment is one of the bigger challenges for do it yourself solar installers. Roof attachments seem like a minor part of the system because they don’t cost much compared to the solar panels and inverters but choosing the right ones is very important. It all starts with what kind of roof you have. The type of roof you have determines the type of solar attachment you’ll need The most common residential roof material would be composition shingle, so we’ll start with that. The best options will have a flashing that is at least 12” long so that when you slide it up under the shingles, it reaches the third course above the hole that you are making. There are many brands out there, but one industry staple is the tried and true QuickMount PV. There are other options available for shingle roofs that don’t include that 12” long shingle flashing but it should be said that just because someone makes something and sells it as a solar roof attachment doesn’t automatically mean it is a good option. Tile roofs are common in places like southern California. There are many different styles of roof attachments that can be used on a tile roof. One of the more popular options is a tile roof hook. This is just want it sounds like, it is a hook-shaped pieces of metal that is lag screwed into the rafter and then hooks up around the edge of the tile so you can bolt your racking to it. What you have to keep in mind here is that the paper that is under the tile is the real waterproofing so that is where you need a flashing so many companies (but not all) include a low profile flashing that sits under the tile and provides flashing for the hole in the paper. If you don’t get the flashing with the tile hook, you can buy them separately. Another common option is the tile replacement mounts. There are made in different styles to match S-Tiles, W-Tiles or Flat tiles. The handy thing about these is that they do actually replace the tile so you end up with a few extra tiles that you can use in case you break some tiles during the solar installation process.  Finally, there are universal tile mount kits that include a small flashing for the paper and a large malleable flashing to flash the tile layer. The up side on these is that they will work with any style of tile and are especially useful if you have non-standard shaped, low profile tiles. The down side on them is that...

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