Monitoring and logging voltage, power, power factor and vars essential in network fringe areas. Let’s look at one aspect – that of Solar PV Inverter Installations to see why this is important?
- Solar PV inverters particularly in remote areas are susceptible to being switched off due to excessive voltage rise or fall. This is part of the design and protection mechanism for the inverter and requirements from the network operators to avoid excessively high voltages been put into their grid. Excessive voltage rise will most likely occur when the sun shines brightly, and the temperature is at its highest (known as high insolation) and electrical energy usage in the home is low because the occupants of the house have gone to work.
- Because of this it is good practice to monitor Solar PV installations for voltage regulation to 254 volts single phase and low voltage down to 207 volts to see what’s happening on your installation. Solar PV installations will switch off when these high or low voltage values occur. This means you are not generating electricity for internal usage, selling back to the grid or charging your batteries if you have battery storage installed.
- In remote areas especially the distribution grid is considered weak (low reactance to resistance (X/R) ratios), because the power generation stations are located far away from the consumption points. Therefore, significant penetration of solar PV installations as we see happening can cause voltage issues such as voltage rise and dip. In certain parts of country Victoria, the switching off Solar PV installations happens continually.
- In addition to monitoring voltage levels it is also good practice to monitor Power factor and vars as Solar PV installations are sometimes required to provide network support by way of vars injection. Both high voltage and the injection of vars into the grid affect the efficiency of the inverters and therefore slow down the cost recovery of your Solar PV installation. High voltage will shut down the inverter and vars injection lowers the useful power output, resulting in loss of feed-in recovery and/or reduced battery charging if you have them installed. High line voltage can cause an inverter to suffer relay chatter with eventual breakdown of the PV Inverter and manufacturers coping the cost of repairs or replacements, not to mention a bad name.
- High voltage in your installation equates to higher electricity bills. This is a fundamental principle of Ohms Law. Power (Watts) equals Amps (I) times Voltage (V) P = I x V. If you are drawing 20Amps at 254V you are using 5.08kW of power. Our electricity bills have a component that charges against kW/hr usage. However, if you are controlling your voltage at 230V you are using 4.6kW of power a saving of 21.95% (Voltage ratio’s squared) on your electricity bill. Control your voltage at 220V then you are saving 33.3% of your electricity bill. The irony of this is you could be having higher electricity bills now, even though you have a Solar PV installation fitted. How is this possible? Experience has shown us that in remote areas the Voltage can rise as high as 275V for long periods typically where no auto transformer tap changing exists. This means your Solar PV inverter installation has switched off and your installation is being subjected to high voltages from the grid. Using the formula above, 20 Amps times 275 Volts equals 5.5kW which equates to a 42.9% higher electricity bill. The moral of this story is you have to control your voltage levels. Trust me no one else is going to do this for you as there is no commercial interest in them doing this for you.
- Low power factor in your installation also equates to higher electricity bills. Typically, not an issue in domestic installations but can certainly be a big issue in Commercial installations such as a McDonalds Restaurant and Industrial installations if not corrected. A component in our electricity bills called Demand Charges penalizes us for wasting good usable power supplied by the network operators by not addressing our low power factor problem.
Our experience shows the Acksen power loggers are simple to use and ideal for measuring and recording the power output of;
- Solar PV inverters.
- Neutral to Earth voltage monitoring especially in areas where earth resistivity is high because of the use of plastic water pipes. A broken neutral can cause dangerous touch potentials.
- Neutral Current monitoring is important where Solar PV installations causes unequal power distribution in the phases
Acksen makes the task of monitoring more efficient by providing combination models, which measure voltage, current, power and power factor in one unit.
When the Acksen loggers have finished recording they can be directly downloaded to PCs using (free supplied) Electrosoft software allowing the data to be viewed immediately on-screen and to be saved or exported for later analysis.
Datapro Communications now located in the Echuca Moama border towns has extensive knowledge in Power Logging and Power Quality Analysis and can provide the report and recommendations on what to do to control Voltage and other electrical parameters effecting your installation and pushing up your electricity bills. For more information please email firstname.lastname@example.org or go online www.dataprocomms.com.au for equipment sales or hiring.