Sizing Morningstar Suresine Inverter and SunSaver MPPT Charge Controller

tanout · July 2017

I want to take the opportunity of my next month vacation to install my first solar system in my sunny town of Niamey (NIGER West Africa ).

I will leave this installation to serve as showcase for educational purpose:
I am making a theoretical projection to use the Suresine at it maximum (300w load/24h).
But I found the battery bank too big for this tiny inverter.
Am I making wrong calculation? 1304 Ah battery bank at 12V seems too huge for tiny $250 inverter

Niamey, NIGER West Africa

Location : 13° 30' N 2° 12' W

insolation average 6.13 kW-hrs of insolation per square meter

Inverter Morningstar SI-300-220V > SureSine 300 Watt /12V Inverter (international) (Oversea project 50Hz/220v)

Charge Controller: Morningstar SS-MPPT-15L > SunSaver MPPT 15 Amp 12/24 Volt MPPT Charge Controller

>> Max load 300w for 24h

300wx24h = 7200 Wh

>> .92 efficiency inverter

7200/0.92=7826 Wh

>>50% of discharge

7826/0.5 = 15652 Wh

> 1 day of autonomy (lof of sun at Niamey)

15 652 Whx1 = 15652 Wh or 1304Ah bank at 12V

Estragon · July 2017

You need to start with actual load requirements, for which the will be two numbers. The first is the largest instant current required, like pump or fridge starting. The second is total wattage needed over time.

If you do have a constant 300w load 24x7, your numbers are about right. That's actually a fair bit of power daily. I use a bit over 1/2 that in my cabin most days. Another missing bit of info is charging capacity. During the day you may be able to charge batteries and also run loads.

Sizing Morningstar Suresine Inverter and SunSaver MPPT Charge Controller

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