Record maximum demand before installing solar and/or battery system.

Before installing a Solar PV plant and/or a battery system is it useful to assess the peak demand (current) of the premises, which in turn will help to calculate the business case and the payback period, which is important for any business investment.

We need to determine when the maximum demands happen and how often, are they hourly, daily, weekly. Carrying out an energy audit will give you this information.

The term Energy Audit is now common currency, with most understanding what it means but perhaps not knowing and how to perform one; the aim of this document is to explain an ‘Electricity Energy Audit’ using the Electrocorder range of data loggers. 

The first thing in any energy audit is to look at the information or data that you already have to hand, this usually takes the form of utility bills, invoices and meter readings, maximum demand meters and payments, this can tell you an lot historically, what it will not tell you is where the energy went, which equipment, circuits, buildings or divisions consumed the energy and when. To answer these questions you have to recorder data over a period of time, you’ll need an Electrocorder.

Circuit Diagrams:

Before you record electrical data you’ll need to know the electrical layout of the system or premises to be audited, ask an electrician to explain the wiring diagram for the premises, if you don’t have one, perhaps you’ll need to create one. The diagram will show you the various circuits and connections of your system, in turn this may help you to determine the best logging points and where to get access for recording.

Pragmatist versus Purist:

There is no need to be a purist; to correctly measure power and energy you need to measure voltage, current, power factor and time however for many situations measuring only current will do!

The voltage you receive from your utility is not constant, generally you have no control over it, those variations will be fairly cyclic over the period of a day or even a week, so in essence voltage can be treated as a ‘constant’ there is therefore no need to record it. For the purposes of a comparative test or audit (before and after) you can robustly use only current. This makes life a lot easier for logging, no direct connection to voltage terminals, simply clip the CTs or Rogowski Coils around the conductors and press the start button to record.

What to Record:

Start at the top (where the power comes in) and record the total usage profile for a period of time, normally a minimum of a week is recommended, if you are happy that each day is going to be the same as every other day then you can log for one day on each of the nodes rather than a week. Generally the longer the recording period the better as you can see if the profile changes much over time and what the changes are linked to, weather, production, shift patterns or other.

You will need to allow time to perform this logging exercise, generally a week for the premises incoming supply feeder. 

Quick Double-Check:

It is always wise to check your results, to make sure there are no fundamental mistakes, check your results against the bills. If you log for a period, say a week, Electrosoft will extrapolate the data and give you estimated power/energy figures for a month, quarter and year, it is always wise to check these figures against the bills.

It is always advisable to document the audit, where you logged the data, as well as a brief summary which should include weather data (temperature, wind, rain, snow) and/or production or other business related data over the logging period, this will help you to correlate the information (in the future) and spot things which may have caused anomalies.

Current only recorders:
EC-3A-RS (5A - 3kA).
CT-3A-RS (1A – 400A).

Power Loggers and Energy Loggers (Voltage & Current recorders):
EC-7VA-RS (5A - 3kA @ 600V).
EC-2VA (300A/300V).
CT-2VA (60A or 400A/300V)

Related guides and products

For energy audits, load profiling, appliance checks and before/after savings proof.

Application guides:

• Energy Audit Loggers: for energy audits, load profiles, peak demand and before/after savings proof.
• Load Survey and Current Loggers: for feeder checks, current logging, load surveys and capacity planning.
• All application guides: choose an Electrocorder by the job or problem you need to investigate.

Relevant products:

• EC-7VAR-RS: Electrocorder EC-7VAR-RS Three Phase Voltage, Current & Power Factor Recorder.
• EC-2VA: Electrocorder EC-2VA Power Logger and Energy Recorder.
• CT-2VA: Electrocorder CT-2VA Power and Energy Recorder.
• AL-2VA: Electrocorder AL-2VA Energy Logger for Domestic and Light Commercial Appliances.