The Fronius inverter will be covered here since it’s one of the most popular inverters. These are widely used with excellent track records and easy to maintain. There are many different manufacturers to choose from and they can mounted in accessible locations. Check out the other recommended inverters on this site as well.
They do however have some disadvantages. Because panels are arranged parallel and series strings shading can become a problem. If one panel is “shaded” the whole string pays the price which causes the enrgy output for that string to degrade.
Now these specs are important:
The Maximum recommended PV input power: This rating should never be exceeded by your panel’s output. If it does your inverter will run inefficiently. You need to match your panels with the inverter.
PV Start Voltage: Let’s you know the starting voltage when your inverter begins to operate. All inverters need a minimum amount before they start outputting their own power into the grid. So when the sun first comes up or is setting there is less panel capability to produce power. This spec is a measure of the overall efficiency of an inverter. You obviously want your system producing as much power as possible for as long as possible.
CEC Rated Power output: Let’s you know the maximum output watts from your inverter which changes with the inverter’s operating temperature. So where you mount your inverter is important (out of the sun!).
Maximum Power Point Tracking (MPPT) range: These circuits allow the inverter to capture the most amount of energy over the course of a day.
Fronius, an Austrian firm that started in the welding and battery charging industries, makes the reliable Fronius inverter line. The German solar market has been thriving for some time, and Fronius began making grid-tie inverters in 1995, so they know what they are doing. Their U.S. residential line is comprised of 2,000, 3,000, 4,000, and 5,100 watt models, and they generally run lighter than the competition thanks to some unique features.
By installing high frequency transformers that are smaller than those in the average solar power converter they drastically reduce the weight of the unit, to an average of 42 pounds versus the average competitor's model with similar output weight of 130 pounds. Also, these transformers allow for greater adaptability, and extended life fans kick in when higher levels of cooling is needed. Environmental sensors, remote monitoring devices and other possible add-ons are all user friendly via the computer-like slide in expansion slots under the housing lid, and let you upgrade your unit easily.
Another nice feature is the conformal coating that every Fronius IG-series solar power inverter receives that protects against corrosion, moisture and other unwanted intrusion. Sadly, many manufacturers just coat the back side of the solar power inverter and leave it at that. But as you know, moisture can seep in everywhere, so these are really great units to use in humid environments, and this NEMA 3R housing is rated for indoor and outdoor use.
The Fronius inverter also has several other nice features like full-featured LCD display, easy-wiring connectors, quick mount capability and pass all FCC compliance regulations for radio/TV noise levels. It is also very easy to add an optional computer display at a remote location through the Ethernet or wireless access.
When you purchase either the 4,000 or 5,100 watt solar power inverter, you receive two energy channels. When there is a lower level of incoming energy, lower production, only one channel is needed to handle the load. When production increases, longer periods of bright sunshine, the second channel kicks in to ensure you are getting the most power possible. These two channels switch their role as master and backup every two days. This means a more efficient system, and longer life since the unit is not running wide open when it does not need to.
The Fronius inverter harnesses German engineering excellence and cutting edge technology to produce reliable units that retail for a very attractive $.80 to $1.00 per watt. CEC efficiency is a more than acceptable 93 to 94.5%, and the entire line is covered with a 10 year warranty.
No matter which solar panel inverter you choose, make sure price per watt is around $1.00, ideally less, it comes with a 10 year warranty, and is at least 93% efficient. When these qualities are present, you know that your grid-tie solar setup is being handled by the best solar power inverter money can buy.