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Choosing the Right Solar Inverter

Choosing the Right Solar Inverter

This guide will help you to choose the best solar inverter for your project. Use this handy reference table to compare the facts. Quickly see the difference in features, performance, warranty and more. Make an informed decision so you know what you are buying. However, these products are ever-changing, with new models or capabilities being added all the time. We'll do our best to keep you up to date with the industry.

TYPE STRING
STRING + OPTIMIZER
MICRO-INVERTER  HYBRID
DESCRIPTION Most common and economical option, works great in direct sun. Add device to back of each panel to "optimize" performance. Each panel operates independently. Add device to back of each panel to "optimize" performance AND convert from DC to AC power. String inverter that works gird-tied or off-grid; Connects solar + optional backup battery to the house.
         
GRID-TIED
Yes Yes Yes Yes
OFF-GRID
No No No Yes
BATTERY READY No No No Yes
RAPID ROOF
SHUTDOWN
Optional Integrated Integrated Optional
         
PERFORMANCE
IN DIRECT SUN
Up to 98% Efficient about 2% more about 2% more Varies
SHADE
MANAGEMENT
Each string Each panel Each panel Varies
PANEL OUTAGE
Affected string non-operational Each panel operates independently Each panel operates independently Varies
MONITORING Whole system or each string Each panel Each panel Varies
         
WARRANTY
STANDARD
10 years 12 years 10 to 25 years 5 to 10 years
WARRANTY
EXTENDED
20 years 25 years N/A 20 years
         
COST Most economical Add 6% to 10% to system cost Add 6% to 10% to system cost Add 10% to 25% to system cost
         
COMMON
BRANDS
SMA
Fronius
Delta

SolarEdge
Tigo Energy
SMA
Fronius
Delta

Enphase Energy
APSystems
Chilicon
Generac PWRcell
Outback Power
Panasonic EverVolt
Schneider Electric
SolarEdge Energy Hub
Sol-Ark
         
WIRING
CONCEPT
Panel output cables are wired together to form a string, up to a dozen or so panels. Inverter has input for 2 to 4 strings. The inverter then combines the output and converts to AC power connected to the electrical box.

Panel output cables are wired to a small optimizer device mounted to the back of each panel. The optimizer's are then connected together to form a string, usually 8 to 15 panels. Inverter has input for 2 to 4 strings. The inverter then combines the output and converts to AC power connected to the electrical box.

Panel output cables are wired to a small micro-inverter mounted to the back of each panel. The micros are then connected together to form an AC circuit, with up to 11 to 16 panels. Each AC branch circuit can then be combined, or wired to it's own circuit breaker connected to the electrical box. Similar to String or string + optimizer wiring.
         
  sma-sunny-boy-us-inverter-cropped.jpg solaredge-inverter-optimizer.jpg enphase-iq7-micro-inverter.png generac-pwrcell-combined.jpg

What to know about solar inverters

There are FOUR basic types of solar inverter: String, String + Optimizer, Micro-inverter, and Hybrid.

A grid-tied, string inverter is the most economical approach. Works just fine in direct Sun when shade is not an issue. Multiple strings, or groups of panels, are wired together, and then connected to the inverter. Each string operates independently. The string inverter may need replacement in 15 to 20 years. Ideal for ground-mounted systems or buildings where rooftop shutdown is not required.

A string inverter with Optimizers has a small device added to the back of each panel to "optimize" performance. Each panel operates independently, it can be monitored, and includes rooftop shutdown capability. Optimizers help minimize shade losses and improve overall performance.

Micro-inverters also adds a device to back of each panel to "optimize" performance AND convert from DC to AC power. Each panel operates independently, it can be monitored and includes rooftop shutdown capability. Micro-inverters help minimize shade losses and improve overall performance. The smaller electronics have a longer lifespan, and a brand like Enphase has a 25 year warranty.

Finally, a Hybrid inverter can work both on-grid, or off-grid with optional batteries. The solar panels and storage batteries are connected in one unit. The hybrid inverter also has an internal power transfer switch to deliver power during an outage. Some customers buy a hybrid inverter to be battery-ready and future-proof the system in anticipation that battery prices will decrease over time. Can add rooftop shutdown or optimizers as needed. Some hybrid inverters even let you connect a fuel generator as another power source to charge your batteries and power your home or business.


The value of good design

Most of the solar kits include an up-front design in the price. We want to make sure you get the right kit, with the right parts, for your project. The design covers topics like the power consumption, system sizing, the electrical connection and the structural mounting. Once the design is complete and the order placed, we will prepare a custom permit plan blueprint for the project. You you can provide the plan to the local building authority and utility for net metering approval. This value-added service is unique to SunWatts. The solar design can be ordered separately to get the project started. Then you will get credit for the design fee with solar kits that are 5kW size or larger.


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