How this Brooklyn condo ensures its solar panels work at max efficiency

One sunny day in the middle of summer, after he’d led the project to install rooftop solar panels on his building, Lucas Parra noticed that the inverter — the device that converts solar energy to useable elec­tricity — wasn’t capturing all of the energy gener­ated. He had a moment of panic: Had some­thing gone wrong with the installation?

Accord Power, the contractor that did the instal­la­tion, reas­sured him that what he was witnessing was ​“clip­ping,” a stan­dard prac­tice done during the peak season to improve solar panels’ effi­ciency through the rest of the year.

Clipping has to do with the rela­tion­ship between photo­voltaic panels and inverters. Inverters are the middlemen of a solar energy system, converting the direct current (DC) elec­tricity produced by solar panels into alter­nating current (AC) elec­tricity so that it can be used to power devices and tech­nology, and connect to the broader elec­trical grid infra­struc­ture. In the solar panel project at 430 Clinton, selecting and sizing the inverter correctly proved crucial to achieving maximum energy effi­ciency and long-term performance.

A key design choice in this project was inten­tion­ally under-sizing the inverter so that the power the panels produce exceeds the maximum capacity the inverter can process at any given time. While this may seem coun­ter­in­tu­itive, it’s a strategic approach that enhances the system’s overall performance.

This method, referred to as ​“energy clip­ping,” is designed to create steadier, longer-lasting energy output. 

If the solar panels produce more energy than the inverter can handle, the excess energy is ​“clipped,” meaning it isn’t converted to AC elec­tricity. This surplus energy dissi­pates as heat or remains unused because the inverter does not process it. This loss is often a trade-off worth making, because solar panels rarely operate at their peak capacity all the time, except on the sunniest days of the year.

While sizing a solar array and inverter for clip­ping isn’t bene­fi­cial in every circum­stance, this design ensures that even during less-than-ideal condi­tions in loca­tions like New York City, such as early morn­ings, late after­noons, or cloudy days, energy conver­sion occurs. Instead of over­spending on larger-capacity inverters that would only be useful during occa­sional peak perfor­mance moments, projects like 430 Clinton prior­i­tize consis­tent energy yield throughout the day.

“By designing your system this way, you have a lower acti­va­tion threshold for the inverter to start converting solar DC energy to usable AC energy. So there’s much more poten­tial throughout the day to generate energy, maxi­mizing solar yield,” explains Patrick Owusu, Senior Solar Program Manager at Solar One.

As a means of achieving this maximum effi­ciency, the engi­neers at Accord Power used a tech­nology called Maximum Power Point Tracking (MPPT). This algo­rithmic tech­nology uses elec­tronic compo­nents in the inverter to opti­mize power output from solar panels by contin­u­ously moni­toring the voltage and current produced by the panels, and iden­ti­fying the combi­na­tion of the two that gener­ates the maximum energy.

Most inverters today come with built-in MPPT tech­nology, but Owusu says it’s always a good idea to double-check when choosing equip­ment for a project. This feature is espe­cially useful for systems like 430 Clinton’s, where the goal is to opti­mize energy produc­tion while staying within budgetary or phys­ical limitations.

“At first I was upset, because I thought we have these solar panels that can produce more elec­tricity, but the inverter is under-dimen­sioned,” said Parra. ​“But they told me not to worry, because in order to really get those few days a year where you can go higher, you would have to get a bigger inverter, which costs a lot of extra money. So for a few days a year, it’s not worth it.”

The under-sizing of inverters at 430 Clinton, combined with energy clip­ping and MPPT tech­nology, demon­strates a care­fully engi­neered approach to achieving consis­tent, effi­cient, and cost-effec­tive energy production.