This article is aimed at overseas distributors, providing guidance on how to select OEM/ODM factories for photovoltaic inverters and energy storage batteries in China. Firstly, distinguish between OEM (customized according to customer design) and ODM (OEM using existing platforms), and then screen according to eight items: certification traceable to the target market (CE/UKCA/IEC, etc.), real firmware development capability (BMS communication protocol), manufacturing and QC depth, product coverage, warranty and after-sales, business terms (MOQ/lead time/payment), standardized import process, and regional reference customers. At the same time, it is reminded to be alert to red flag signals such as certificates without numbers, specifications, refusal of third-party inspection, and significantly low quotations. The DEMUDA five step import process (demand → solution → technical confirmation → production delivery → after-sales) is used as a mature case.

This article proposes a four step configuration method for off grid/weak grid hybrid photovoltaic systems in areas with unstable power grids: first, calculate the actual daily load (including household appliance start-up surges), then calculate the battery capacity based on 1-2 days of backup days and 90% discharge depth, then divide the daily electricity consumption by the peak sunshine hours and 0.75-0.8 loss coefficient, and amplify the photovoltaic array by 1.5-2 times. Finally, select a hybrid inverter with continuous power coverage for simultaneous loads, 1.5 times surge, and support for generator input. And remind to avoid common errors such as setting batteries according to optimistic values on sunny days, ignoring starting current, and reducing ratings due to high temperatures.

This article compares low-voltage (48V/51.2V) and high-voltage (160-700V) hybrid photovoltaic inverter systems: the low-voltage system has simple wiring, low cost, and wide battery compatibility, making it suitable for small apartments below 12kW, renovation projects, and budget constrained scenarios; High voltage systems have low current, low line loss, thinner cables, and flexible expansion, making them suitable for three-phase residential buildings, industrial and commercial areas above 10-15 kW, and future expansion needs. When selecting, it is determined based on power, number of phases, expansion plan, and on-site wiring distance, and once the voltage architecture is selected, it cannot be mixed.

This article explains the capacity calculation method for energy storage to reduce electricity demand in European commercial and industrial sites: electricity demand is charged based on the highest power of the billing period (usually the highest 15 minute average), while photovoltaics only reduce electricity consumption and cannot reduce demand. The battery must discharge and peak when the load approaches the set upper limit. The capacity is calculated in five steps based on the annual 15 minute load data: setting the target peak value, converting available energy (including discharge depth and round-trip efficiency), verifying the discharge C-rate, and iterating according to the actual electricity price structure. The article provides examples, key points of European compliance (carbon footprint declaration, battery passport, proportion of recycled materials), and an inquiry list.