Solar Builder

JAN 2018

Solar Builder focuses on the installation/construction of solar PV systems. We cover the latest PV technology (modules, mounting, inverters, storage, BOS) and equip installers/contractors with tips and tools to make informed purchasing decisions.

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Page 40 of 47

SOLARBUILDERMAG.COM | 41 Lesson specifically for the solar industry to prove this point. At the high end, Trojan's Industrial grade lead-acid batteries can last up to 17 years, delivering 3,600 charge/discharge cycles at an average 50 percent depth of dis- charge (DOD). In comparison, Trojan's solar absorbed glass mat (AGM) lead-acid battery lasts eight years, delivering 1,700 cycles at a 50 percent DOD. You need to consider how much your cus- tomer wants to participate in the storage process. Less-expensive flooded lead-acid batteries — costing from $100/kWh to $200/kWh — provide between 600 and 1,200 cycles and require water refilling main- tenance, but AGM or gel chemistry lead-acid batteries, which are 20 percent more expen- sive, can provide about 1,700 cycles without requiring the extra maintenance, according to Erguen Oezcan, senior sales director for renewable energy at Trojan Battery. The safety and environmental story of lead-acid is tricky. On the one hand, flooded batteries carry the extra costs of a venting system needed to draw off the hydrogen gas that is formed over time as well as a contain- ment basin to guard against spills (a code requirement). But, on the plus-side, lead-acid batteries are 99 percent recycled — one of the most recycled products in industry today. Lithium batteries are not yet recyclable. There are some relatively new additions to basic lead-acid chemistry to consider. Carbon-enhanced anodes limit the forma- tion of sulfate deposits, which hamper perfor- mance and decrease battery life. Other inno- vations include the use of metallic agents to enhance the electrolyte, layered insulating wrappings for AGM mesh and so-called moss shields that limit internal shorts. Up and comer: Lithium-iron phosphate When lithium-ion batteries came into common use, they seemed destined to cap- ture the bulk of the battery market. But high prices — which thankfully are falling rapidly — combined with fire concerns have encour- aged manufacturers to experiment with a variety of other lithium chemistry variations. One that's emerging is lithium-iron phos-

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