Energy Demand Analysis

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A significant proportion of the income from your investment in a renewable energy system like solar PV comes from the money you save by using the electricity you generate on site. Every unit (kWh) of electricity you generate and use yourself is one that you do not purchase from your electricity supplier. On sites like chicken sheds, dairies and holiday accommodation it is essential that you match your electricity demand profile as closely as possible to your generation profile to maximise your savings on purchased electricity.

Whilst the output from a hydro unit is relatively stable over a 24 hour period, the output from a wind turbine is much more variable from hour to hour. The generation output from a solar PV installation is quite predictable from week to week and subject only to weather variations.

3ph  >  1ph

Most solar PV systems over 10kW will be generating at 3ph. That means that the electricity being generated is split equally over the 3 phases, L1, L2 and L3.

The majority of the demand loads in a typical chicken shed will be single phase. especially the lighting. Some 3ph motors may be employed on muck and egg belts and in chiller units but as they are relatively low powered they too are often single phase. The electrical distribution design for a chicken shed that has a 3ph electricity supply requires that the single phase loads are distributed as evenly as possible over the 3 supply phases to minimise "phase imbalance" on the incoming supply.

At any moment during a typical day the solar PV system might be generating an output of 90kW equally over the 3 supply phases. Depending on the electrical distribution design in the shed and the activities at that moment it is quite possible that phase L1 has a demand of 25kW and is therefore using most of the electricity being generated on that phase with only 5kW being exported. Phase L2 might have a demand of just 5kW and is therefore exporting 25kW whilst phase L3 has a demand of 35kW and is importing 5kW.

If the site had an export Power Purchase Agreement in place the exported power on L1 and L2 might be earning the client around £0.06 per kWh whilst the imported power on L3 would be costing closer to £0.14 per kWh.

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Demand Analysis

To improve your consumption of on-site generation and reduce the cost of purchased electricity it is important to start with an analysis of how and when you are using electricity over at least a typical 2-3 day period. This will identify both the electricity used in a defined period on each supply phase as well as the peak demand and time of day.

We use sophisticated non intrusive logging equipment to capture this data and build a profile of your electricity use. Analysis of this data can result in fairly minor changes to when you undertake specific activities during each day, or alternatively modifications to your distribution wiring to provide a better balance of your loads over the 3ph generation and supply. The objective is to maximise your use of generated electricity and minimise your purchase of purchased electricity with a corresponding reduction in your costs.