3kW Off Grid Solar System In Kenya

Munene Kasina asked me a question about his system through email.

He wanted to run his farm completly off grid because there are no power lines available.

These are the loads Munene wants to power:

• 2 Fridges: 250W x 8hours x 2 fridges = 2000Wh
• 2 TV’s: 150W x 4hours x 2tv’s = 1200Wh
• 2 Laptops: 50W x 8h x 2laptops = 800Wh
• 12 LED Lights: 5W x 8h x 12 lights = 480wh
• Inverter idle draw: 25W x 24h = 600Wh

We have a total daily power consumption of 5080Wh.

Munene’s farm is located in Kenya with the following sunhours:

I then used my off grid solar calculator to determine how many batteries he needs to run this system. Using the following metrics:

• 48V battery
• 1 day of autonomy (budget constraints)
• 4 sunhours (worst case scenario)

We need a 48V 134Ah lithium battery and 1300Watts of solar panels to support the loads with one day of autonomy.

Munene has chosen a 3kW Growatt hybrid inverter (SPF-3000 TL HMV-48).

Here is the diagram of the system:

We can see that the solar panels are wired in a 2S2P configuration, this means 2 panels in series and then in parallel.

From there it goes into a DC breaker and there is a SPD (surge protection device) that’s installed if there is an over-voltage from a lightning strike. This will protect the inverter from over-voltage.

We can see that we have an AC breaker in the same box, according to European and united states electrical regulations, these need to be separated. But this could be legal in Kenya. The installation was done by a company, so i assume they know what they are doing.

The DC solar power goes into the hybrid inverter’s MPPT input. Cables then go into the battery and AC out goes to a change over switch. I’m not sure what the change over switch does, But i assume it turns off the AC power. It then goes into an AC breaker before going to the consumer unit.

The system upon completion:

4 pieces 435W solar panels are used in a 2S2P configuration. They are monocrystalline from Jinko for a total of 1740Watts.

Bill of materials

• • 1  Felicity Lithium 5kW Battery = Kshs 170,000
  • 1 Growatt 3kW hybrid inverter = Kshs 55,000
  • 4 Jinko 435W solar panels = Kshs 64,960 (Kshs 16,240 each)
  • 2.5 Kw Aluminium Solar Mounting Structure = Kshs 31,250
  • 6sq. Mm Solar DC Cable = Kshs 9,000
  • 4 Meters DC Battery Cable = Kshs1,800.00
  • 63A Suntree Suntree DC breaker = Kshs 3,900
  • 80A Suntree Battery Fuse c/w Holder  = Kshs 4,500
  • 40A Manual Change over switch = Kshs 3,500
  • System Installation cables and accessories = Kshs 8,000

TOTAL = Kshs 368,110 = $2,825 (per todays exchange rate)

Additional feedback after several months of running:

Runs great, added 50W of 24/7 loads and 100W of night load (12hr). On average the battery is at 25-30% at sunrise and fully charged by 1pm.

If you have questions about the system, feel free to ask them in the comments below so we can get a discussion going.