Today we will introduce a design of 5kw solar system off grid for small fish farmer including the configuration and some calculation methods step by step.
There are some basic data to be clarified for the preparation of solar power system design.
First of all, the user’s voltage & phase should be identified, either to be the single-phase AC 110V, 120V, 220V, 230V, or 240V or the three-phase AC 380V, 440V, 480V, etc. It decides the output specification of the solar inverter.
Second, the load type should be confirmed to be either inductive load or resistive load, because the load type can decide the inverter’s on-load power and output waveform.
Third, the full-load operation time, namely average daily electricity consumption, should be determined. In case of the grid-connected photovoltaic power generation station, there are no energy-storage devices, then only a reasonable power of the photovoltaic module is needed. In case of the off-grid solar photovoltaic power system, the battery capacity should be calculated, including the system’s self-stored power when there are no photovoltaic power generation conditions during successive overcast and rainy days.
Design of 5000W off-grid solar power system
Now we take a design of off-grid solar power system for a small-scale fish farmer near a lake as case study. Due to long-distance power grid construction, not only the cost is high, but also the conductor power loss and voltage loss are huge. Meanwhile, the stability of power use can not be ensured due to the typhoons, and the accidental power failure happens on a frequent basis, which can affect the power use for production and life. Therefore, the off-grid solar power system is adopted. The sunlight radiation intensity in the daytime is high, and the power generated by solar power system is directly provided to the solar inverter output to support the operation of electric devices. At the same time, the batteries are charged, and provides the power for the devices via the inverter at night.
1. Survey on electricity demand
Here is some basic data to be known before. The voltage here in daily life is AC 220V 50Hz, and the commonly used appliances or devices mainly include:
Ten sets of fishpond pump oxygen-generating machines (300W).
One set of Television + Satellite receiver (200W).
One electric cooker (750W).
One induction cooker (2,000 W).
One small refrigerator (100W).
Lighting (100W).
These devices are not used simultaneously. The pump oxygen-generating machine operates in the daytime when there is sun radiation but rests at night. The power of other devices is around 3000W, and their daily electricity consumption is around 10 kilowatts. Since the lake surface illumination is adequate, the self-stored electricity on overcast and rainy days is not taken into consideration.
2. Solar inverter.
According to the data provided by users above, at this off grid solar PV system design, the all-in-one solar inverter with MPPT charge controller is adopted. This 5000W solar inverter with MPPT charge controller has 48V 7kV power capacity, power factor ≥ 0.8 and conversion efficiency ≥ 85%. The actual on-load power can reach 5000W, which can satisfy the requirements of user’s devices output power.
