自建了一个小型光伏发电站，3块太阳能板日发电量4度

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I built a small photovoltaic power station on my rooftop with three solar panels generating 4 kWh daily.

Two 350W monocrystalline silicon solar panels + one 350W polycrystalline silicon solar panel connected in parallel, through an MPPT solar charge controller and grid-tied inverter. Energy is stored in four 12V20AH lead-acid batteries (2 parallel x 2 series). The grid-tied inverter is set to fixed output of 400W (my home network cabinet typically consumes around 400W, effectively offsetting this portion of electricity usage).

No anti-backflow system was implemented since installing it would require running wires from the rooftop to the ground floor electrical box, which would be inconvenient.

Daily generation is about 4 kWh on sunny days, and 2 kWh on cloudy days. Total cost was over 2000 yuan, with an estimated payback period of 3-4 years.

Equipment Purchase Links:

Photos

Three solar panels:

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MPPT controller and photovoltaic inverter:

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MPPT controller app screenshot showing maximum power of ~707W from three parallel panels:

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Photovoltaic inverter web management interface:

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Additional current transformer installed on inverter AC output cable:

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Home total power consumption waveform showing significant reduction in phase B power consumption during daytime:

2025.6.9 Update: All three panels now use MPPT photovoltaic optimizers with connection changed from parallel to series configuration. Daily generation increased to ~5 kWh on sunny days!

MPPT Photovoltaic Optimizer is a power electronics device installed at the solar panel end. Its core function is to enable each panel to operate independently at optimal power points through Maximum Power Point Tracking (MPPT) technology. Key benefits include:

  1. Increased Power Output: Solves panel shading and degradation differences, avoiding “weakest link” effects in string configurations, boosting generation by 5-30% compared to traditional setups
  2. Optimized System Design: Supports heterogeneous panel configurations, flexibly adapting to complex installation environments (e.g., varying roof orientations/inclinations), reducing design constraints
  3. Enhanced System Reliability: Single-point failures don’t affect other panels, reducing series circuit risks and extending system lifespan
  4. Smart Monitoring & Maintenance: Real-time individual panel monitoring enables rapid fault detection and simplified operations
    Ideal for distributed PV systems and legacy station retrofits, replacing traditional centralized management with distributed optimization to improve photovoltaic system efficiency and economics.

2025.11.3 Update: Added an additional 350W monocrystalline solar panel in series, and replaced lead-acid batteries with lithium iron phosphate (LiFePO4) batteries (pre-built battery pack purchased from Xianyu marketplace with protection board, 700 yuan for 1.2 kWh capacity). Original lead-acid batteries had significantly degraded performance - their short cycle life made lithium iron phosphate the better long-term choice.

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Original Chinese article: https://blog.zeruns.com/archives/55.html

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