This system was designed for an old Solarkobo client who wanted a system at a second residence. SolarKobo is a stockist of batteries, solar panels, charge controllers and inverters. Our clients mostly depend on us to recommend brands to use in designing their systems. This project however, was an installation-only project as the client provided all the components.
Nine (9) 300W CSun monocrystalline solar panels was used in designing the system. The panels in three strings with three panels per string. Expected output from the panels was estimated at 2,700W.
Inverter and Battery
The battery that was used was a 160Ah Felicity Li-ion battery. This would decide the brand of inverter. The client initially provided a Xantra inverter but was advised against using it by our engineers because, charging-wise, it was incompatible with lithium-ion batteries. He decided to procure a 5kVA Felicity inverter.
In comparison with other battery technologies, Li-ion batteries charges extremely faster than other rechargeable batteries. The reason is because while lead acid batteries require a three stage charging profile where each stage progressively lowers the charge current and can be bulk-charged up to 80%, then absorption-charged from 80% to about 95% and then float-charged to 100%. Li-ion batteries however do not have such a similar three-stage charging and can be bulk-charged all the way up to 100%.
Also, li-ion batteries can withstand very rugged power conditions than other type of batteries. They can supply electricity to very high power appliances. Lithium-ion batteries are maintenance-free for life. This removes concerns by the clients about any regular maintenance procedures.
They however cost a premium. They also require an on-board protection circuit to maintain the battery voltage. This makes them even more expensive than they already are because of their manufacturing costs. The goal of the protection circuit is to limit the peak voltage of each cell during charge and prevent the cell voltage from dropping too low on discharge. In addition, it helps to monitor the cell temperature to prevent temperature extremes. With these precautions in place, the possibility of metallic lithium plating occurring due to overcharge is virtually eliminated.
Learn more about lithium-ion batteries here.
A special feature of this installation is the voltage regulator or stabilizer. AVRs are considerations for users that use their systems on auto-mode or charge it with generating sets or depend on grid power from NEPA. It serves to help keep the input voltage at the required level. For instance, when grid power is available and is below 180V, the inverter will not internally bypass to allow charge and NEPA usage simultaneously. So as to make up for the discrepancy, the output supply will be from batteries both while NEPA is present and when it is absent. This increases the chances of the battery bank always been drained and/or overused.
The system incorporates an 80A Felicity MPPT charge controller. Of the two types of charge controller technologies, the MPPT solar charge controller is the ultimate in solar controllers. Though relatively very expensive and larger in size, they can help users save considerable money on larger systems since they provide 10 to 30% more power to the battery than the PWM and have efficiencies reaching up to 98%.
In addition to the protection features provided by the inverter against reverse current, overload and overcharge, the system incorporates extra protection features including AC and DC circuit breakers and surge adapters. They offer additional protection to the client's investment. They also make it easy and safe to disconnect the system from the panels in the case of emergencies like lightning that could damage the inverter or solar panel fires.
Designed for residential use, the solar panel were mounted on the roof and the batteries, charge controller, voltage stabilizer and inverter installed in a non-living area of the house.
SolarKobo helps its clients in Lagos and everywhere in Nigeria figure out their power needs and make the best possible choice of all solar products including batteries, solar panels and charge controllers. We also have university-trained engineers who provide the best possible installation services on order.