100 Day Challenge #94: If you have a sunny roof, consider going solar
Renewable energy has made huge strides in the last decade, and solar is no exception. As you can see in the SEIA graph, in the last ten years the cost of solar has plummeted and the annual installation in the U.S. continues to rise. Depending on the electricity rate you pay and your roof's sun exposure, solar can be an amazing investment that not only reduces your carbon footprint but also gives your energy independence and adds tremendous value to your home!
Optimal panel placement
Before diving into the solar panel deep end, you first want to determine if you have the right roof for panels. The two main components to keep in mind when searching for an optimal panel placement are:
Access to plenty of sunlight. I know it may seem obvious, but if your house is surrounded by trees and your roof gets hardly any sunlight, then you're not a candidate for solar. Trees are awesome, and we would never encourage anyone to cut one down to go solar. If you live in (or near) a major city in the U.S. then checkout Google Project Sunroof. Although it's not 100% accurate and isn't very updated, it can give you an idea if you have a good roof for solar. In their images, the lighter the roof color, the better solar potential that surface has. As you can see, our house is unfortunately not a solar candidate because of all the surrounding trees. We love our trees though!
A favorable roof orientation. The main thing to keep in mind is that if you're in the northern hemisphere, you want to orient your panels as close to south as possible (if you're in the southern hemisphere, then you want to orient your panels north). In Dallas for example, we're in the northern hemisphere so the sun is always tracking south of us regardless of the time of day or the season. A western orientation is a good second option with an eastern orientation coming in as a close third.
Tip: when you're receiving solar quotes, ask the providers for a shading report. Any reputable provider will run a shading report to accurately estimate your expected annual solar production. This ensures that they're taking into consideration any obstacles that might cause shading including trees, chimneys, vents, and even adjacent buildings. If they don't offer this report to you from the beginning, make sure to ask for one and definitely get your hands on it before you sign anything!
What to look for in a solar panel
There are so many panel options out there, and it can be overwhelming choosing the panel that's right for you. Because the technology changes so quickly, find a solar provider that you trust to give you the most up to date information about the market and your best options. However, here are a few thinks to look for in a solar panel; these are great points to bring up with any solar provider who is presenting you with a quote to ensure that they're giving you a full picture of the product they're offering.
Product warranty: we wouldn't recommend purchasing a panel with a warranty that's less than 25 years. Panels are meant to last a long time, and if the manufacturer is a reputable one, they will have no issues warrantying their products for at least that time period.
Production warranty: this is the second aspect of the warranty that you want to look at closely. The production warranty tells you what percentage of the panel's original production is guaranteed over the warranty period. In the market today, top-tier panels will guarantee around 90% of the panel's original production over the 25 year warranty period. This is key because you want to make sure you're getting a panel with a low degradation rate.
Panel efficiency: in today's market, a good solar panel will have an efficiency in the high teens or low twenties. Even though seeing an efficiency of 20% may seen low, it's actually really good for today's technology.
Power output: good residential panels today have an output of over 300W. The panel's output is also a good number to use when you're comparing costs during your research process; breaking comparisons down to a $/W basis is helpful!
Cell technology: we won't go too much in depth on this, but the main takeaway is to go with monocrystalline, not polycrystalline cells. Monocrystalline is the newer and more efficient technology. You can visually tell which cell type it is because a monocrystalline cell will look black, whereas the polycrystalline will have several shades of blue.
Pros and cons of inverter types
Panels are the first (and sometimes) only element that people associate with a solar system, but the inverter you choose can really make or break your solar experience. The two main categories when it comes to inverters are microinverters and central (or string) inverters. There are pros and cons to both, but here is a simple breakdown.
String inverters: these convert the direct current (DC) that your panels produce into alternating current (AC) at the inverter. String inverters are cheaper, but not recommended. When your panels are connected to a string inverter, you run the risk of lowering overall production because your system will only be as productive as your weakest panel. In other words, the production of each panel is capped by the least productive panel in the system. For example, if one panel is shaded, then the production of all the other panels will decrease to match it. You can imagine how much production potential is lost with this setup! String inverters were used back in the day when the microinverter technology wasn't developed, but if a solar provider is trying to install a string inverter today, they're just going the cheap route! Another disadvantge with a string system is that you aren't able to monitor your system's production at the panel-level.
Microinverters: this is generally what is recommend for residential projects. These devices convert DC to AC at each individual the panel. Each panel in this setup is unaffected by its neighboring panels and it will produce at its maximum potential. You can monitor your production at the panel-level, which is key for diagnostics throughout your system's lifetime. Enphase is one of the best manufacturers for microinverters in the market today.
Central inverters with power optimizers: this is a hybrid scenario that is newer to the market. You still have a central inverter but a power optimizer is connected to each panel. With this setup, you get panel by panel optimization and monitoring (like microinverters) but your power is converter from DC to AC at the central inverter. For larger systems, this option is typically cheaper than microinverters. SolarEdge is a great company if you're considering this product.
Monitoring: this is tied to the type of inverter you have, and although you might not think of it when choosing your system, lifetime monitoring is extremely important. Make sure it's included in your quote! Even if you don't want to be super hands-on and vigilant regarding your system's production, panel by panel monitoring is still important for diagnostic purposes and tracking solar output.
Check what buyback programs are available to you
Even if your system is sized to perfectly offset 100% of your annual energy usage, there will be times throughout the day when you're producing more energy than your home requires and that given moment. When this happens, that excess energy is sent back to the grid through a meter that is able to track both incoming and outgoing electricity. Because of this, it's very important to check if you have a solar energy buyback program available to you through your electricity retailer. Many different factors will play into this such as your state's laws, whether or not you're served by a co-op, or if you're in a deregulated energy market.
Call your energy retailer and ask them if they have a solar buyback program and what the details are. The jargon can get pretty technical, but the two main details to clarify (if they have a solar buyback program) are:
At what rate to they buy the solar energy back? You want to know how much money you'll get for every kWh you send back to the grid. Your retailer can either pay a wholesale rate for it (while still charging you retail for the electricity you consume), a retail rate, or give you a 1 for 1 credit for any energy you send back to the grid.
Does their buyback rate apply to excess energy produced over the course of the month, and do their credits roll over month to month? Not only will you have excess production at certain times of the day, but in months when you're not running your AC very much and you have peak solar production, it's quite possible that you can have an overproduction over the course of the month. It's important to clarify what your retailer would do in this case and if your solar credits from one month would roll over to the next.
If you don't have access to a solar buyback program where you live, then this definitely changes the financials for going solar. In that case, you can consider investing in battery storage so you can take advantage of all your solar production on-site, or install solar to offset a lower percentage of your electricity usage and minimize the amount you're sending back to the grid.
This is the perfect time to look into going solar because 2019 is the last year that we're under the 30% Solar Investment Tax Credit (ITC) program in the U.S. This means that you can subtract 30% of the total cost of your system (materials and installation) from what you owe in taxes at the end of the year (always check with your CPA to confirm your personal tax situation). Next year it begins to scale down and drops to 26%, so you still get a great incentive even if you don't install your system by the end of the year.
If you want to read a full and candid account of someone's experience going solar in the Dallas Ft-Worth area, check out Lindsey Perkins Wade's article "Going Solar? Here's What We Went Through From Start To Finish." It's an awesome read, and Lindsey does a great job at describing the entire process.
Going solar is not a small decision; to do it right definitely requires time, research, and most likely a little bit of patience. However, if you have the right roof for it, then going solar can be one of the most rewarding home improvement projects for both the environment and your pocketbook!