Typical Design of Small-scale PV Off-grid System

Due to the difference in the level of economic development, there are still a large number of remote areas that have not solved the basic electricity problem and cannot enjoy the convenience brought by modern civilization, while PV off-grid power generation is mainly to meet the basic electricity demand of residents in areas without electricity or with little electricity.

500W Off-grid PV System Solution

The customer's electricity demand:

3pcs 20W lamps, working 5 hours a day on average,

50W TV, working 4 hours a day on average.

The location is a herdsman's house within Inner Mongolia.

Demand analysis:

The total power of the load is 110W, all are resistive loads, and the average daily power consumption is 0.5 degrees.

Equipment selection:

According to the type and power of the load, a 12V20A PWM controller and 500W pure sine wave inverter are selected, a 320W monocrystalline PV and a 12V 100AH lead-acid battery is used for the solar system. The controller, inverter and battery are made into an integrated cabinet, which is convenient to carry.

5kW PV off-grid system solution

Customer's electricity demand:

lighting 200W working 6 hours a day,

refrigerator 50W working 24 hours a day,

two one-hp air conditioners working 12 hours a day,

TV 50W working 10 hours a day.

There are also washing machines, desktop computers, rice cookers, electric fans and other home appliances, and the customer's installation site is in Liangshan, Sichuan.

Demand analysis:

First of all, the total load power: lighting 200W, refrigerator 50W, air conditioning 1500W, TV 50W, washing machine 300W, desktop computer 200W, rice cooker 1200W, electric fan 100W, a total of 3600W.

Then statistics of daily electricity consumption: lighting 1.2 degrees, refrigerator 1.3 degrees, air conditioning 5 degrees, TV 0.5 degrees, washing machine 1 degree. Desktop computer 0.5 degrees, rice cooker 1 degree, electric fan 0.5 degrees, an average total of 11 degrees, most of the electricity consumption is in the evening, about 8 degrees.

System Design:

The total power of the load is 3.6kW, so the inverter with 5kW power is chosen to give the air conditioner a margin to start; the light condition is good in Liangshan, Sichuan, and it is counted 4 hours a day on average,

so 3.8KW components are chosen for the design, which can generate 15 degrees a day on average, the efficiency of the off-grid system is low, generally about 0.8, and 12 degrees of electricity is available on average every day,

so it can basically meet more than 99% of the electricity demand. The battery is designed to generate 10 degrees of electricity to meet the demand for electricity in normal weather, because the customer has a limited budget and does not consider the weather conditions of rainy days and bad light in winter.

Equipment selection:

Guravat SPF 5000ES control inverter with an output power of 5KW, 10 monocrystalline 380W modules and 8 12V150AH lead-acid batteries.

Electrical scheme:

All 10 modules are connected in series to the PV input of the inverter, and 8 12V150AH lead-acid batteries are connected to the battery input of the inverter in the way of 4 series and 2 parallel.

The electrical diagram is as follows.

12kW PV Off-grid System Solution

Customer's electricity demand:

lighting 300W working 18 hours per day,

refrigerator 50W working 24 hours per day,

2 sets of 3 HP air conditioners working 20 hours per day,

TV 50W working 6 hours per day,

1.5kW water pump working 1 hour per day.

There are also desktop computers, electric fans and other home appliances.

The customer's installation site is in Guilin, Guangxi, which is a small store with more power consumption during the day.

Demand Analysis:

The total power of the load is about 8kW, of which the inductive load is 5kW. Calling the customer's electricity bill list, the electricity consumption is more in summer, about 40 degrees, and about 20 degrees in winter.

System Design:

Considering that most of the users are inductive loads, the inverter selects the frequency isolated control inverter integrated machine, the component design is 11kW,

which can generate 40-50 degrees of electricity in summer and 20-30 degrees of electricity in winter, basically meeting the customer's needs, and the battery uses 20 degrees of electricity.

Equipment Selection:

SPF12kW HVM control inverter, the inverter supports PV 7kW access, so add a 48V100A PV controller, the modules are 33 pieces of 340W, the total power is about 11kW. 12 pieces of 12V200AH batteries are used, the total capacity is 28.8 degrees.

Electrical scheme:

18 modules are connected to the inverter, 3 series and 6 parallel, 15 modules are connected to the PV controller, 3 series and 5 parallel, and 12 batteries are used in the way of 4 series and 3 parallel.

The electrical diagram is shown as follows.

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