So you want to go off grid or have a hybrid solution where you have some power security during a power outage. The first thing that you need is somewhere to place the Solar PV panels, and in Southern Africa you need roof areas facing in a Northerly direction or you can make use of an East / West configuration. Why Northerly? Our Sun in South Africa travels from East to West and because we are south of the equator, the sun is positioned North of South Africa as it travels. In winter the sun is lower or closer to the horizon and if you used a roof with a steep southerly slope, you probably would harvest very little to zero energy in winter. Of course you can tilt panels on brackets, this all adds to the cost of the installation. Next you can build structures, like a carport to mount panels or if you have a lot of land you can build structures to mount the pv panels onto. These structures can be simple as the rails for the PV panels can be laid on top of these structures, now you can build your structures with the perfect tilt towards North to have maximum energy yield. The structures must be concreted into the ground so that wind does not tip the structure and destroy the pv panels. There are mounting brackets for most roof types, from asbestos, tiled, metal, aluminium and bare frames.
Cables from pv panels, although rated for direct sunlight should be shielded from the sun.
Load= We normally install a power logger on site for a minimum of one week to understand the customers load profile, how much power is used, Kwh or kilowatts per hour per day. We use this data to correctly size the system, in an off grid scenario the PV panels KWp compared to inverter KVA has to be oversized in order to charge batteries and power the load, even in overcast weather conditions. In grid tie solution or a hybrid solution this is not as critical although there are benefits. If you can feed back to the grid with compensation then oversizing your solution could be advantageous to you. With all of the above solutions we design in such a way that the customer can start small and increase the solution size over time without having to replace equipment, but rather adding to the existing solution.
Types of solutions based on your need.
Grid Tie Solution = saving on electricity bill, no batteries, can include generator integration.
Hybrid / Off Grid = Power security where you may or may not have electricity supply from ESKOM or your power utility. Battery backup and you could have wind turbines connected and a generator.
Why wind and or generator if you have batteries? With only battery backup if we have two weeks of solid rain, the PV system will produce some power but this may not be enough to charge the batteries and power the load in an off grid scenario. Wind can blow during rainy season, and at night to assist in charging the batteries. The generator we can set to start when the batteries a low, that could be 40% or anywhere below that, and the generator would then charge the batteries, this means that the generator is more of an emergency appliance. In a hybrid solution we must ensure that we have large enough battery storage to power the essential loads for a minimum of 2 hours (based on load shedding outage hours).
Energy Storage= Li Ion Battery backup, well proven technology that does last, used in electric vehicles for a number of years. Design using a generator as backup to charge batteries as the cost of batteries for 3 days autonomy (no electricity and no sun) could be too expensive to start. Generator charges batteries when they reach a low pre-set level. OR if in an area that receives regular wind, then add a wind turbine to the mix as an alternate source to charge the batteries.
Summary:
Roof Space for PV Panels
Load requirement for premises
Type of solution – Grid Tie – Hybrid or Off Grid.
Dive into various options and see which solution will be the most cost effective and the most practical for the customers application.
Backup energy and what loads are essential, spend a lot of time looking at what is required as this is where a lot of money can be saved or wasted.
Any questions, please contact us as this is just an overview and is in no way exhaustive.
