From small to large-scale purposes, the recognition of battery-based off-grid and grid-connected backup methods has grown significantly worldwide. With that, the demand for bigger, larger capability methods has additionally grown.
Though lead-acid battery banks are definitely scalable to swimsuit the wants of most residential and industrial purposes, battery applied sciences similar to lithium-ion now provide clients another with larger cost effectivity and quick discharge functionality in a smaller footprint.
The introduction of lithium-ion batteries into the residential vitality cupboard space has introduced with it a brand new set of challenges. Defective or broken lithium-ion cells can result in thermal runaway reactions which, like dominos, have an effect on adjoining cells and can lead to hearth. As the dimensions of those methods will increase, so does the danger of igniting flamable off-gasses and potential explosion.
This lithium-ion thermal runaway danger has triggered new laws that will impose extreme restrictions on residential system sizing and the placement of the vitality storage methods (ESS) in relation to the house and different system elements in addition to obligatory protections associated to fireside suppression within the occasion of thermal runaway
Whereas these concerns and protections are mandatory for lithium-ion expertise, many of those security considerations don’t apply when utilizing conventional lead-acid batteries.
NFPA 855 overview
In 2019, the Nationwide Hearth Safety Affiliation (NFPA) published NFPA 855, the primary hearth safety normal for stationary ESS. Historically, battery-based residential methods had been a lot smaller than what’s allowed beneath the NFPA 855. This newly created normal specifies the obligatory necessities for general monitoring and administration of ESS for hazard mitigation to mitigate thermal runaway dangers.
The most important modifications have been within the most saved vitality for ESS and the place they could be put in.
Contemplating the added hearth dangers, residential ESS methods utilizing lithium-ion, movement and sodium nickel chloride batteries are restricted to 600 kWh and, in lots of circumstances, ESS sized over 20 kWh would now not be put in within the house or connected storage. The brand new laws would require that bigger ESS should be put in in a separate devoted constructing with hearth detection and suppression methods, and have restricted entry for personnel accustomed to their operation, upkeep and testing.
These modifications will deal with security considerations with respect to thermal runaway and enough hearth suppression. Nonetheless, the times of basements or garages lined with massive battery-based methods will quickly come to an finish – regardless of the battery chemistry. Clients ought to anticipate to see an increase in the price of ESS installations as installers adapt to fulfill these new necessities.
The necessities for bigger ESS have modified considerably.
ESS over 20 kWh in measurement can be topic to testing in accordance with UL 9540 and UL 9540A for hearth testing and propagation. Producers should full this testing on merchandise supplied to be used on this area as they might want to comply with these new laws upon inspection.
UL 9540 points for lead-acid batteries
These new laws would apply to large-scale ESS whatever the chosen battery expertise. Though the utmost saved vitality (kWh) is limitless when putting in conventional lead-acid batteries, UL9540 and UL9540A necessities for the system would nonetheless apply.
As described, an ESS is a system that provides the flexibility to retailer vitality to be used as wanted. The system contains all the elements together with inverter/chargers in addition to electrochemical cells (batteries) used for storage.
At present, one of many key challenges confronted by conventional lead-acid battery producers is in assembly UL 9540 and UL 9540A compliance when the battery itself is just not a full ESS and can’t be examined as such.
In contrast to a typical lithium-ion battery, which incorporates an inner battery administration system to manage cell cost, discharge and monitoring of working circumstances, a standard lead-acid battery is solely that – a battery. To satisfy the brand new laws, lead-acid batteries should be examined along with different system elements – a requirement which isn’t solely time-consuming however expensive and can in the end dictate the price of vitality storage as we transfer ahead.
Deep cycle lead-acid batteries have performed a key position within the inception and ongoing progress of the renewable vitality business. Lots of the standard batteries chosen by installers immediately have carried over from different industries similar to marine, industrial and motive energy purposes. Lead-acid batteries proceed to supply probably the most economical and lowest price per kWh vitality storage resolution for many residential methods on account of their comparatively low price of producing, availability and excessive charge of recyclability. The laws of NFPA 855 might drastically change all of that, though the dangers associated to thermal runaway don’t apply.
Jeff Myles is advertising supervisor of Rolls Battery.