The next article was despatched by the cost controller specialists at Morningstar Corp. We’re internet hosting a Morningstar webinar on Nov. 17, masking off-grid improvements. Sign up here to join us stay or to observe on-demand.
The “massive format” 72 cell nominal 24 V photo voltaic module has been a staple of commercial and different off-grid photo voltaic system design for a number of a long time. Over a lot of that point, cell and module sizes have been rising. Whereas these will increase traditionally have been linear and incremental, in recent times they’ve been accelerating. A significant component driving this pattern is the truth that grid-tied utility-scale residential and business photo voltaic designers who additionally deploy 72 cell modules want bigger cell sizes to extend the photo voltaic module’s whole energy output.
As a result of they enhance energy extra cost-effectively, bigger cells and modules can accommodate bigger hundreds, and may supply better photo voltaic “autonomy” in areas with extra restricted sunshine (decrease insolation). Along with upfront price financial savings, the additional energy from these bigger modules can enhance battery well being at off-grid websites by producing increased common battery state of cost (SOC) when the load the system is working isn’t elevated. Since batteries are sometimes the most costly element in an off-grid photo voltaic system, this vastly improves ROI by way of battery prices and the effort and time to exchange them.
Know-how, competitors and economies of scale have pushed module costs decrease through the years, reducing the fee per watt. Module manufactures have additionally been dialing within the Voc and Isc of those bigger modules to assist massive residential, business and utility-scale grid-tied tasks profit from diminished prices related to combiner packing containers, racking, basis, cabling and set up. These advantages outweigh any destructive penalties that large-cell modules may need on massive grid-tied system designs.
Nevertheless, most off-grid techniques, usually consisting of just some modules, are unlikely to see those self same price financial savings. This implies bigger modules current the next potential destructive penalties for off-grid designers:
Module weight concerns. Heavier modules can enhance transportation and set up prices, in addition to racking wanted. Module weight will increase may have an effect on deployments as a result of OSHA and different rules (and simply practicality) may require two individuals as an alternative of 1 to raise bigger, heavier modules into place. Though grid-tied tasks may also be affected by heavier modules, off-grid tasks are extra delicate to them as a result of they oftentimes deploy fewer installers (typically only one particular person), and off-grid techniques usually tend to depend on mounts and helps that aren’t as massive and steady as these related to massive utility-scale grid-tied photo voltaic techniques.
Elevated floor space results. Potential issues right here contain areas with increased wind speeds, heavy snowfalls, and extra. That is particularly a priority with cellular telecom and site visitors signaling/warning functions, the place techniques modified with new modules are moved to new places that will encounter increased wind velocities.
Different potential downsides
- Newer modules typically have totally different Voc rankings and totally different Voc temperature coefficients than the older, smaller modules they’re changing. A system designed with elements (cost controllers, breakers, fuses and wire sizes) that have been initially able to dealing with most array voltages may not meet the brand new necessities, particularly in chilly climate, after a number of years of swapping out new bigger modules within the design. If the modules that make up the array of an off-grid system produce voltage in extra of the photo voltaic cost controller’s Voc score, the cost controller will probably be broken and trigger the complete system to fail.
- Bigger modules may enhance the array present output past acceptable ranges for an off-grid system’s photo voltaic cost controller. Whereas this usually is not going to completely injury the controller, it’s not good for the controller’s well being, and it’ll trigger the cost controller to close off charging till the present drops right down to acceptable ranges. Within the meantime, the system doesn’t obtain energy to cost batteries in periods of the day when the solar is providing essentially the most energy.
- Bigger enclosures could also be wanted to accommodate bigger controllers and different upgraded BOS.
- Shading issues. Arrays that previously managed to flee close by shading may now be subjected to partial shading at sure instances of the day, as soon as bigger modules are swapped-in.
- Provide chain and sourcing points may pop up if new BOS elements are wanted. Provide chain and sourcing points can relate to the brand new modules themselves and likewise to new BOS elements which can be essential to help the brand new modules. Costs for brand new elements could be increased, and extra importantly, the lead instances to obtain the required BOS elements could be a lot better.
- BOM modifications in addition to design drawing/documentation modifications.
- Designers may wish to proceed to deploy older, smaller modules in a few of their techniques, however these modules may not be obtainable as a result of the trade has moved on from them. Therefore, designers may be compelled to make use of bigger modules and establish and handle any destructive impacts.
- Producer and design firm reputations may very well be compromised. It is crucial for producers, distributors, and designers to teach their clients to assist them know concerning the penalties and errors to keep away from when contemplating module upgrades. Designers’ reputations can both be broken or improved, relying on how properly they convey and assist clients plan for the consequences of recent modules.
Due to the sturdy demand from the utility scale grid-tied trade, the pattern for bigger modules will proceed. Because the off-grid market is a lot smaller than the grid-tied photo voltaic market, it’s straightforward for module producers to miss considerations associated to off-grid system designers. Happily, in the long term, as the worth of those new bigger modules continues to fall, the bigger module pattern will even profit off-grid designers, so long as designers establish, perceive, and regulate accordingly to mitigate the potential destructive penalties.
Within the quick run nevertheless, off-grid designers ought to pay attention to the potential pitfalls of bigger modules and ensure to design their techniques round them. Modifications in module electrical traits from yr to yr, which was small and predictable, will now must be scrutinized extra rigorously.
For corporations missing devoted photo voltaic design assets, step one is to think about the advantages of further schooling/coaching and on-line assets, comparable to off-grid string calculators, in addition to in search of assist from skilled third events to navigate by these modifications.
Mark McHenry is the advertising supervisor for Morningstar Corp., a pacesetter in photo voltaic cost controllers and inverters.