This quick guide twill help you to design PV systems with SolarEdge optimizers and inverters. With a few basic principles, you can easiliy design systems with SolarEdge. Just remember to design for power watts, not voltage or current, and you will be on your way to simplifying PV designs. To design residential systems with SolarEdge, there are 3 top things to consider.
SolarEdge Power optimizers are designed for most high power modules today. The specifications make it easier than ever to match them to your PV modules.
P300 is the baseline model designed for standard 60 cell modules up to 300 watts DC STC rated power input, operating at less than 48 Voc or open circuit voltage
P320 is the model designed for High Power 60 cell modules up to 320 watts DC STC rated power input, operating at less than 48 Voc or open circuit voltage
P400 is the catch all model designed for 72 cell, 96 cell and other modules like with high power LG, Panasonic or Sunpower modules, up to 400 watts DC STC rated power input, operating at less than 80 Voc or open circuit voltage
P405 is a catch all model designed for 72 cell, 96 cell and other modules like with high power LG, Panasonic or Sunpower modules, up to 405 watts DC STC rated power input, operating at less than 125 Voc or open circuit voltage
P600, P700 are for commercial, three-phase systems with each optimizer connected to two solar panels with combined total output of 600 or 700 watts DC STC rated power, operating at less than 96 Voc or 125 Voc open circuit voltage, and up to +5% power tolerance allowed
Design SolarEdge module optimizer strings to power and not to voltage. With SolarEdge, there is no need to perform voltage calculations to determine string length. You just need 2 numbers: minimum and maximum string length:
240Vac single phase has minimum of 8 optimizers, maximum of 5,250 watts per string for each DC input
Example: For 260 watt modules we divide 5,250/260 = 20.2. Then round down to 20 for a maximum of 20 modules per string.
Each inverter allows input of 2 or 3 strings, with PV+ and PV- input connectors. For larger systems or when practical for system layout, the strings may be combined in parallel using a string combiner box like the MidNite Solar MNPV4. The use of string combiners must conform to the inverter specifications and NEC code.
SolarEdge offers up to 135% oversizing of its inverters. That means that for a 10,000 watt AC inverter, you can add 13,500 watts of DC power. For minimum sizing, while there is no set requirement, SolarEdge recommends sizing of the inverters down to 50% of nameplate (e.g. 5,000 watts of DC power using the 10,000 watt AC inverter).
While it is a common practice to oversize traditional string inverters, this is less important for SolarEdge. Technically, the system will always keep the voltage fixed at 350Vdc, meaning that there is no efficiency loss for undersizing. Financially, the inverters are very low cost and the optimizer costs scale directly with module count.
If you ever want to install batteries, the SE7600 inverter can handle from 3,800 watts DC to over 10,000 watts DC, and it will be upgradable to StorEdge in the future.