An off-grid solar power system - providing reliable continuous power to industries

Image Credit: IRENA - Solar Off-Grid System, Mali

Conversion of sun energy into an electric current is one thing, getting your factory equipment to use that power is another. As larger firms continue to accept solar power alternatives, they will need to consider equipment that can generate enough clean power for heavy machinery. To support industrial activity, solar power outputs will need to align to expectations of supporting current industrial machine use which often uses 3-phase A.C power that is more cost-effective, easy to transmit, manipulate, and whose generating and transmission equipment turns out to be smaller and more efficient when compared to single-phase. 

Such a system can help unconnected communities yearning to develop economically according to Jesse, from systems design at Knights & Apps Ltd  who recently spoke to Cleanleap. According to him, these systems carry the potential to help phase out power outages, connect remote schools, villages, remote tourist hotels, remote government security posts and administrative units, wildlife conservation sites, village workshops, distant campsites, manufacturing firms, and medical facilities that requires uninterrupted power throughout.  

Knights & Apps Ltd is a Kenya-based company that designs home and industrial solar power supply systems and other environmentally friendly solutions and one of their industrial solar supply solutions, which was exhibited at an International Trade Fair recently held in Nairobi. It is a smart scalable 3-phase off-grid PV power system. The Nairobi Agricultural Show went under the banner "Enhancing Technology in Agriculture and Industry for Food Security and National Growth," and these 3-phase systems can be helpful in powering agriculture to support medium and large-scale farming. 

Clients can use the system to power their equipment and in future, as an income generating endeavour (by selling excess power) once the government passes laws that allow such microgrids to hook to national grid. Producing up to a maximum of 12Kw, 3-phase solar power system can be used to run industrial equipment and any other heavy-power operations while eliminating downtime at night when there is no sunshine.  

"The whole system is able to provide continuous 3-phase power ... without any break or blackout," said Jesse. 

The firm is planning to start selling power to the national grid power utility once the necessary pending grid-tie feed-in bills are passed into law. Currently, it installs these systems for private entities and homes. They begin by analyzing consumer needs for power before designing any system. This allows the client to only get and pay for the amount of power they need.  

"Once a client indicates they would like to have solar power, we do a site visit whereby we conduct a detailed survey," said Jesse. The company uses equipment to determine daily power consumption patterns and usage for all loads, and discusses with the clients about their preferences. Such data is then analyzed and used in the design process. They also select the right designing software based on the customer's power consumption needs.  

The outcome of design is the basis of cost estimation and the customer is informed of the estimates, after which they may decide to discuss further the project scope (for instance if they want phased implementation). The company takes over each process after the client approves the project.  

The off grid solar system is comprised of: a PV array of interconnected solar modules, PV grid-type 3 phase inverter, bidirectional battery inverters, battery bank and communication and monitoring equipment.  The system converts solar power to DC current of about 400 - 800 V, which is fed into PV grid-type inverters. The excess power from PV inverters is used to recharge the batteries, which will be the source of power at night after convection to AC by the battery inverters.  

 

 

 

 

 

 

 

 

 

 

 

 

It is expected that related technologies will become more advanced, which will make solar alternatives more affordable and acceptable. Already, the world is warming to another innovation with regard to off-grid system batteries - Lithium-Ion batteries, which have a longer life than lead-acid batteries which reach natural limits faster especially in extreme temperature environments.

Calculation of the amount of power to be used by each device - termed as load analysis - is the first step towards the off-grid system design. 

There is no doubt that 3-Phase Off-grid power systems can help in powering far-fetched rural areas, as well as reducing environmental damage from fossil fuel sources. Poor access to funding, low awareness of solar capabilities, and a delay in putting into place the legal framework that allows development of solar (grid-tie feed-in bill) are some of the hurdles standing in the way.