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Installation of PV panels east-west or south?

Nov 24, 2021Expert advice, Solar

The popularity of photovoltaic installations in which panels are installed in an east-west (EC) rather than south-facing direction is growing. The method of mounting photovoltaic panels has evolved in recent years. Until a few years ago, the angle of the ideal inclination of photovoltaic panels was assessed on the basis of latitude, so that the sun’s rays fell on the solar panels perpendicularly most of the time, and the optimal orientation of their orientation was the south (for the northern hemisphere). In this way, the yields from the panels were optimized per unit of installed power (kWh / kW), which ensured maximum production.

South facing modules produce more energy during the day. And yet, as various analyzes show, EC systems in some cases offer the possibility of greater savings, because they better fit the needs of the facility, especially in the case of households. The energy production curve of EC systems installed on a flat roof is much smoother than for panels installed facing south. It is characterized by higher yields in the morning and noon hours, and much lower around noon, if we compare them with the standard arrangement of the modules.

The absence of a sharp jump in energy production from the panels around noon, when demand is usually very low, is more beneficial to the grid. The flattening of the “peak” of the production curve also enables better selection of the inverter. It is not selected for peak production, which will take place only for a few minutes a day. Consequently, the inverter is loaded more evenly throughout almost the entire day. As a result, the size and cost of this device are also reduced.

Panels installed on a south-facing flat roof are more favorable to users with overall high energy demands. Observing the daily profile of electricity consumption, higher energy demand around noon (i.e. the peak of production with the classic arrangement of panels) occurs in the winter months. However, if we look more closely at the consumption profile, it turns out that in some facilities, EC-facing panels can produce 49% more energy during hours of higher demand than those facing south (based on a Pecan Street Research study).

When choosing a photovoltaic system, it is worth suggesting the daily profile of electricity consumption and the characteristics of the facility. Sometimes east-west solar systems can turn out to be much more advantageous than the southern systems we are used to.

You can calculate the relative energy yield in relation to the optimal position – the table below will help you with this.