The inverter is the “brain” of your solar system. It’s job is to flip the DC current made by the panels to the AC current you need in your house. It also reports to the monitoring how your system is doing. Inverters come in two types. Each variety has pros and cons.
Central or String inverters: One inverter controls the whole system. If it’s a really large system or the group of panels face in different directions, each group may have its own inverter. This can cost a bit less up front (less equipment) and makes the install pretty straightforward. It’s also easy to service since it’s on the wall instead of your roof. However, if the inverter or any one panel has a problem, the whole system stops making power – just like an old string of holiday lights stops working if one bulb burns out. Least efficient power conversion of the two types. Limits system power output to whatever the least performing panel is putting out. This configuration also sends high voltage current from the panels on the roof to the inverter on the garage wall. Lifespan is about 12-15 years.
Micro Inverters: Each panels is equipped with its own small inverter. The current is flipped right at the panel so only low voltage AC current is traveling across your roof and walls. This type of inverter has the highest conversion efficiency because the electricity travels the least distance before being converted to AC. Because each panel has its own inverter, each panel can perform to maximum output no matter what the rest of the panels are doing. If there is a failure or shade on your system, it means that only those panels that have an issue or are in the shade are impacted. It also means you can easily expand the system without worrying about string sizing limits or having to add another central inverter. This is the type of inverter Rabo installs exclusively. The reason for that is pretty simple. They install quickly and they last a long time without problems. Central inverters last 12-15 years on average. Microinverter lifespan is 25 years. In over 21,000 micro inverters we’ve installed in the last 5 years, we’ve only had 59 need replacing. That’s a 0.2% failure rate. As a company, we like things that work reliably for a long time without us sending a truck out to make repairs. When you’ve been around for over 20 years, you know that servicing an existing job is not the best use of your employee’s time. As a customer, we think you might also a trouble-free clean energy solution.
Central inverter with Optimizers: This set up tries to get the benefit of micro inverters – where individual panel performance is not capped by the lowest performing panel, but still has the handicap of a central inverter. If the main inverter goes, the whole system goes down. Lifespan is about 12-15 years depending on what brand of central inverter is installed.
This is an old myth that has been debunked over and over again, yet still gets repeated. Think about it. Why would a profitable company with a sterling reputation install exclusively a product that failed in the only market they operated in? If this rumor was at all true, wouldn’t you be seeing something like “Robco installed crappy inverters that died in the heat!” over and over again in our online reviews? Microinverters failing in the heat is not being mentioned in any review for Robco (or for any company that installs microinverters in any of the hot places in the world) because this idea that they fail in the heat is just not true. We installed several thousand microinverters in 2017 and 2018 -the two hottest years ever recorded in Las Vegas. In the last 5 years, we have installed over 25,000 microinverters. They are deployed all over Las Vegas, Henderson, Pahrump and Mesquite. The older systems have been through multiple punishing summers. The hardware failure rate is currently .27% or less than 100 out of 25,000. The internal operating temperature on Enphase microinverters is 185 degrees. You roof gets hot, but it’s not 185 degrees up there. Extreme heat poses no issues for microinverters.
Solar panels have no moving parts to wear out or need maintenance. On premium panels like the LG ones installed by Robco, unless there is impact to cause physical damage, they very rarely fail once installed. If a part of the system is going to die, it will be the electronics in the inverters. Central inverters with or without optimizer are far more heat sensitive than micros.
We have selected LG Neon2 panels for three reasons:
- #1 LG is a very established company with a huge variety of precision manufactured products – dishwashers, TVs, phones, refrigerators, etc. Unlike companies that just make solar panels, their future is not dependent on just solar. A dip in the solar market or a change in solar incentives will not cause them to go out of business.
- #2 Due to that manufacturing expertise, LG offers one of the highest efficiency panels with the lowest degradation rate in the industry.
- #3 LG has one of the highest market shares in the solar industry. Unlike Panasonic, which has tied their future fairly tightly to one particular company, if one installer selling LG panels or batteries was to go out of business, LG will still be around to back their warranty.
When your system makes power, it either has to be used in your house or go out to the grid for your neighbors to use. There are no batteries attached by default to store that power for later. If your system is not making as much power as you need (it’s cloudy, it’s the middle of summer or it’s night time), you’ll get power from the grid, just like you do now. At the end of the month, NV energy will record how many kilowatt hours they sent you and how many you sent to them. They bill you for the difference between what you sent back to the grid and what you used – the “net” in net-metering.
You will always have a bill to NV Energy after you go solar. They are acting as your “virtual battery” and that service does not come free. If everything works out perfectly, your new monthly bill should average about the same amount as the lowest power bill of the year. If you’d like to look at adding batteries to your system, we can help with that.
Example month 1: It’s April and the weather is sunny and clear but it’s not really hot yet so you haven’t fired up the AC. Your house made 2,000 kwh from your solar. You used 1,500 of that in your house and sent 500 kwh to the grid. You pulled another 300 kwh from the grid for your night time use. 500 sent back – 300 used = 200 over. NV Energy gives you credit for 95% of that amount, so you’d bank 190 kwh to use later. For this month, you’d get a bill from NV Energy only for the basic connection charge, taxes and fees – about $18.
Example month 2: Now it’s May and it’s starting to get hot. Your house made 2,200 kwh from your solar. You put it off as long as you could, but toward the end of the month, the AC had to go on. Your house used all 2,200 kwh you made this month, so no power was sent back to the grid. You also pulled 500 kwh from the grid for your night time use. For that month, you use from the grid was 500kwh. You had 190 kwh in the bank, so NV Energy would bill you for 310 kwh plus basic connection charge, taxes and fees – about $53.
How many panels we suggest for your solar project is based on how much power your house used in the last 12 months. That’s why someone living in the same exact floor plan, facing the same direction as your house, might only need 14 panels (they don’t have any kids and you have 4) or they might need 30 (someone in the house works at home and runs a lot of power tools all day). NV Energy has us take the annual use total for your home (obtained off your power bill) and run it through a formula. That tell us the maximum number of panels we can install under the current incentive program.
If you have not been in your home for a full 12 months, we have to use the square footage formula dictated by NV Energy.
It’s all math, not preference on our part. Every installer has to size systems the same way, so if you got two quotes that are wildly different in size, you should ask more questions.
With all the companies flooding into Nevada to get in on the solar gold rush, a little homework can REALLY pay off. Here are some things to look for in any contractor you are seriously considering.
- Verify they have a Nevada Contractors License
A lot of companies are coming in from out of state. They don’t know how our rules work and they often try to cut corners and make promises they simply cannot keep. It’s illegal to sell a solar system or install solar without a valid C2, C2-G NV Contractor’s license. Make sure you only deal with a licensed contractor. Here’s where you can check their license status. Their license number must be on all their materials by law. No license number on the quote or business card is a red flag. If you did decide to do business with an unlicensed contractor, you’ll be unable to make a claim to the Residential Recovery Fund if something goes wrong.
- Check their power production projections
Use PVWATTS.NREL.GOV to verify that the system will produce what they promised you. If that production is overstated, that means you’ll have a longer payback and get less value for your money.
- Check the review sites.
What do other customers say about them? Check Yelp! Angie’s List, Facebook, Google and the Better Business Bureau. You can also check with the Contractor’s Board for Disciplinary actions.
- Watch for Misleading Claims & Pushy Sales Tactics
Going solar is not like buying a pack of gum or shopping for a washing machine. Most people take a few weeks to a few years to decide to go solar. Misleading claims such as “you’ll never have a power bill again!” or ” the Nevada government pays you to go solar” are all over the internet. If the sales person is hounding you to make a decision as soon as they finish their presentation, telling you the price is only good for 48 hours or trying to scare you with claims like “the net metering tier is almost full” or “we’re raising prices next week,” these are all red flags. At the same time, be on the look out for too good to be true offers. If their
- Ask about the company and their experience
Questions you should be asking about the company and how they do business include:
- How long has the company been in business?
- Is the company profitable?
- How many installs have they done? How many of those are in Las Vegas?
- How long have they been installing solar in Las Vegas?
- Do they service & install their own systems?
- How long have their installers been with them?
- What are the warranties they provide? State law requires a minimum 10 year workmanship and roof penetration warranty for solar.
- Is there an install in your area you can see in person?
- Can you speak to one of their customers without the sales person present?