Another off-grid solar energy installation completed by the renewable energy experts at SPECIALIZED SOLAR SYSTEMS for a client living completely off the grid on a small holding located between Karatara and Rheenendal in the Garden Route, South Africa.

The off-grid energy systems supply electricity to the household and workshop and is completely isolated from the public electricity network.

These systems are independent power stations capable of powering a wide range of applications with dependable and reliable electricity that is no different to that supplied by the national electricity grid.

Whether it be for a small or large new or existing home, a station, business or an entire community that depends on large diesel generators, off-grid stand-alone power systems are commonly the reliable, clean, hassle free, cost competitive answer!

It is our recommendation that energy saving principles are put into practice and taken into consideration before such a system is purchased i.e. low wattage lighting, gas stove/geyser etc…

Summary of Equipment used for the installation:

  • 2250 Watt Array of Solar Modules [10Year Guarantee, 25Year 80% Yield]

  • 1380Amp hour 2V Cells at 24V with take-off leads, battery floats, log book, distilled water x 20L drum, interconnecting cables and hydrometer [1Year Guarantee, 10-15Year Lifespan]

  • 85Amp MPPT (Maximum Power Point Tracker) [5Year Manufacturer Guarantee]

  • Victron BMV700 Precision Battery Monitor [5Year Manufacturer Guarantee]

  • 5KVA 24V 120 Victron Multiplus Inverter/Charger [5Year Manufacturer Guarantee]

  • System Programming and Maintenance/Owner Training    

Breakdown on supplied equipment for the off-grid installation:

Solar Module Arraytajaard 2016 batts

To have an average input of 12kWh/day from your solar modules in George, South Africa. Solar module arrays totalling 2250Watt were used. These solar modules have a 10year manufacturer’s product guarantee and a terrestrial 25year 80% yield.
NB. Solar yield is determined by location, orientation, shading and panel surface condition, system usage and weather condition.
34° Tilt Angle Facing North with full day exposure to the sun i.e. no shading.

Battery Storage Capacity

1380Amp 10-15year Lifespan, 2V Millennium Deep Cycle Batteries with interconnecting cables were used. These batteries have the capacity in storage at 9kWh’s usage per day and cycle the system at 27% maintaining system efficiency and battery lifespan, please note that actual cycle ratio’s may vary from installation to installation depending on system use.
Please note during daylight hour’s system runs off PV as Primary, Battery as secondary.

BMV-700 Precision Battery Monitoringbatts

The essential function of a battery monitor is to calculate ampere-hours consumed and the state of charge of a battery. Ampere-hours consumed is calculated by integrating the current flowing in or out of the battery. In case of a constant current, this integration is equivalent to current multiplied by time. A discharge current of 10A during 2 hours, for example, amounts to 20Ah consumed. All our battery monitors are based on a powerful microprocessor, programmed with the algorithms needed for precision monitoring.

Standard information and alarms:
- Battery voltage (V).
- Battery charge/discharge current (A).
- Ampere-hours consumed (Ah).
- State of charge (%).
- Time to go at the current rate of discharge.
- Visual and audible alarm: over- and under voltage, and/or battery discharged.
- Programmable alarm or generator start relay.

Solar Charge Controller - MPPT (Maximum Power Point Tracking)battery monitor

PV voltage up to 150 V
The Blue Solar MPPT 150/70 and 150/85 charge controllers will charge a lower nominal-voltage battery from a higher nominal voltage PV array.
The controller will automatically adjust to a 12, 24, 36, or 48 V nominal battery voltage.

Ultra-fast Maximum Power Point Tracking (MPPT)mppt

Especially in case of a clouded sky, when light intensity is changing continuously, an ultra-fast MPPT controller will improve energy harvest by up to 30% compared to PWM charge controllers and by up to 10% compared to slower MPPT controllers.

Advanced Maximum Power Point Detection in case of partial shading conditions

If partial shading occurs, two or more maximum power points may be present on the power-voltage curve.
Conventional MPPT’s tend to lock to a local MPP, which may not be the optimum MPP.
The innovative Blue Solar algorithm will always maximize energy harvest by locking to the optimum MPP.

Outstanding conversion efficiency

Maximum efficiency exceeds 98%. Full output current up to 40°C (104°F).

Flexible charge algorithm

Several preconfigured algorithms.
One user programmable algorithm. Manual or automatic equalisation. Battery temperature sensor. Battery voltage sense option.

Programmable auxiliary relay

For alarm or generator start purposes

Extensive electronic protection

Over-temperature protection and power derating when temperature is high.
PV short circuit and PV reverse polarity protection.
Reverse current protection.

CAN bus
To parallel up to 25 units, to connect to a Color Control panel or to connect to a CAN bus network
PV short circuit and PV reverse polarity protection. Reverse current protection.

Pure Sine Wave Bi-Directional Inverter/Chargerinverter

1 x 5000/24/120 Victron Multiplus Inverter/Chargers
•    Continuous output power at 25’C (VA) per unit 5000
•    Continuous output power at 25’C (W) per unit 4500
•    Continuous output power at 40’C (W) per unit 4000
•    Peak Power (W) per unit 10 000

Multi-functional, with intelligent power management

The Multiplus is a powerful true sine wave inverter, a sophisticated battery charger that features adaptive charge technology, and a high-speed AC transfer switch in a single compact enclosure. Next to these primary functions, the Multiplus has several advanced features, as outlined below.

Two AC Outputs

The main output has no-break functionality. The Multiplus takes over the supply to the connected loads in the event of a grid failure or when shore/generator power is disconnected. This happens so fast (less than 20 milliseconds) that computers and other electronic equipment will continue to operate without disruption. The second output is live only when AC is available on one of the inputs of the Multiplus. Loads that should not discharge the battery, like a water heater for example can be connected to this output (second output available on models with 50A transfer switch only).

Virtually unlimited power thanks to parallel operation
Up to 6 Multi's can operate in parallel to achieve higher power output. Six 24/5000/120 units, for example, will provide 25 kW / 30 kVA output power with 720 Amps charging capacity.

Three phase capability
In addition to parallel connection, three units of the same model can be configured for three-phase output. But that’s not all: up to 6 sets of three units can be parallel connected for a huge 75 kW / 90 kVA inverter and more than 2000 Amps charging capacity.

Power Control - Dealing with limited generator, shore side or grid power

The Multi Plus is a very powerful battery charger. It will therefore draw a lot of current from the generator or shore side supply (nearly 10A per 5kVA Multi at 230VAC). With the Multi Control Panel a maximum generator or shore current can be set. The Multi Plus will then take account of other AC loads and use whatever is extra for charging, thus preventing the generator or shore supply from being overloaded.

Power Assist - Boosting the capacity of shore or generator power

This feature takes the principle of Power Control to a further dimension. It allows the Multi Plus to supplement the capacity of the alternative source. Where peak power is so often required only for a limited period, the
Multi Plus will make sure that insufficient shore or generator power is immediately compensated for by power from the battery. When the load reduces, the spare power is used to recharge the battery.

Four stage adaptive charger and dual bank battery charging

The main output provides a powerful charge to the battery system by means of advanced ‘adaptive charge’ software. The software fine-tunes the three stage automatic process to suit the condition of the battery, and adds a fourth stage for long periods of float charging. The adaptive charge process is described in more detail on the Phoenix Charger datasheet and on our website, under Technical Information. In addition to this, the
Multi Plus will charge a second battery using an independent trickle charge output intended for a main engine or generator starter battery (trickle charge output available on 12V and 24V models only).

For more information on how to get off the grid, please contact us at This email address is being protected from spambots. You need JavaScript enabled to view it.


Posted in: Off-Grid Installations