Are you referring to connecting to the inverter by wifi or lan, a third party device, or a service provided by energy providers?
If the first one, the wifi app is completely useless but we do have a spare lan cable in the ceiling which another electrician cut too short to reach our bedroom but will be long enough to reach the connection point on the inverter.
If the electrician who installed the system ever returns to connect the pump and electronics on our solar hot water system to the backup box so it will still work when the mains is off, I will ask him to also connect the lan cable to the inverter.
We have been waiting less than 8 months so it should be getting close now.
If the last one, the only service Ergon provides is the rough end of a pineapple.
Iâm talking about a device completely separate to the inverter which utilises current transducers on various cables to measure gross PV system output and gross household loads, enabling you to see the full picture at reasonably high accuracy, much better than what the inverter can tell you (which is only showing the PV system, not loads).
You wont find this sort of monitoring for grid connected systems, but this is the monitoring I have on the DC side of things here, reduced to 5 sec intervals instead of the recorded 1sec so my computer doesnât get too bogged down with calculations. 17280 lines is better than 86400 in a spreadsheet!
Here are a couple of the various graphs I prepare each day
Data from 25th June 2019
Click on the graphs to display them clearly.
NET charge/discharge, showing PV output, state of charge and voltage
The standard Sungrow hybrid better and inverter system should have included a digital AS clamp type meter device that monitors outgoing as well as oncoming power. It is a necessary part of the installation which enables the home owners to control when and how battery power is exported or limit battery use to self consumption.
As @gordon suggests many of the supplied systems reduce logging to 5 minute averages.
The Sungrow install should include the following, assuming as you suggest there is also the ability to power the home when the mains goes off.
See system with EPS overview on pages II and III
The cloud based data recording system should provide all of the data indicated in the user guide. Excuse the fuzzy content. However you do need to set up an account and complete configuration of the connection.
Included with the inverter, the wifi connection, or for hybrid inverters the optional wired ethernet connection should have been set up and made operational by the installer. It is part of the product provided by Sungrow. Every owner has paid for it! That is what I received with both the systems we have!
P.s.
Power tidal flow charts are accessible from the web app or a PC. Refer p11,12 for an overview.
For Qld Energex and Ergon have a joint standard for the performance of small scale PV systems connected to the grid. (10kVA single phase 30kVA 3 phase).
As a consequence grid connected PV Inverters are required to be set to operate at a set pf of 0.9 lagging or alternately to adjust the power factor progressively in response to the line voltage. This is irrespective of the level of DC power being provided by the PV array to the inverter. Up to 10% of the PV panel output, of the maximum rating of the inverter is not available for household consumption or export.
Table 2 and Fig 1 nominate power factor settings for their respective networks. In non technical terms power factor (pf) is a ratio between Real Power measured in kW and Apparent Power measured in VA. At a pf of 1.0 the Real Power exported is the same as the Apparent Power. Setting an inverter to operate at a pf of 0.9 reduces the power exported by 10% of the PV Inverter maximum rating. Hence a 5kVA system will operate at a max of 0.9 x 5kVA = 4.5kW.
Inverters may also reduce output on hot days to protect their internal electronics, reduce generation to stay within supply authority export limits, or shutdown in response to high or low line voltage. The scheme implemented in Qld by Ergon and Energex may be different to how other states and supply authorities require PV inverters to adjust to changes in line voltage.
note: Hybrid Inverters
Depending on configuration hybrid (grid and battery connected systems) can typically charge the battery at the same time as supplying power to the house and or exporting any surplus to the grid. As for the example provided by @Fred123 the DC power reported for the roof panels (6.6kW DC) can be greater than the AC power rating of the inverter (5.0kVA - 4.5kW at 0.9pf) generated and reported in the graph if power is being diverted to battery charging.
As an aside, it can also be difficult to identify when an inverter is operating in a power limiting mode if there is no user visible alarm issued by the inverter monitoring. Every product is different.
One other factor that may also mask high grid voltage; considering how Sungrow Inverters derate their output as the air temperature inside the inverter cabinet increases. This is also not unique to Sungrow products. Each manufacturer needs to manage the heat output by the inverter.
The Sungrow data sheets for several different models indicate that power derating commences at 45C ambient air temperature, although I have not found any details of exactly how the derating is applied, and how this affects generation.
The caution here particular to Sungrow is their marketing appears to misrepresent the environmental specification of their products.
The temperature measured by the inverter is not the outside air temperature, which is ambient. It is the internal air temperature that the inverter reports and would appear to respond to when reducing power generation? Observation suggests that on a sunny day the 5KVA (nominal 5kW) inverters reach their 60C internal maximum temperature with only a 30 C ambient air temperature. Not ideal for a large portion of Australia.
Notes:
The data sheet is from the manual for a Sungrow SH5K-20 hybrid grid connected inverter manual.
Some of the settings or characteristics of PV inverters are specified in Australian Standards or the network managers connection manuals. In general all inverter manufacturers minimise the need to publicise that their products may perform at less than full power. A simple reference of compliance with the listed Australian Standards etc in the fine print covers all options.
The CEC accredited designer of each installation should take all these factors into account in providing the minimum annual generation a system will deliver. It is one of the CEC approved retailers quoting commitments. There are two caveats. One with shading, and the other as @gordon reminds us, system generating losses due to poor grid voltage management by the distribution authorities.
(Edited comment, correction)
Off grid or isolated systems may maximise generating potential. Actual not. As @gordon points out in the next post, you loose out when you canât consume or save any excess PV generated energy.
Blowing a fan over the heat sink fins, or other parts of a hot inverter will delay or prevent output limiting in many cases.
For off-grid, the generating is managed by charge controllers, and maximising potential PV system output is generally only likely until the battery is 70-80% charged (Bulk charging stage, unless you have a load to make up the difference), after that the charge controllers limit PV output so that the battery voltage doesnât go too high.
I donât believe that the output is being affected by temperature as once the output gets to maximum in mid to late morning, it stays like that until mid afternoon apart from interuptions by passing clouds.
The temperature is lower is the mornings than in the afternoons and the in-built fan only occassionaly operates.
The inverter does not display its own internal temperature but it does display the temperature of the LG RESU10 battery which is currently 30 degress whilst the inverter is currently outputing 4.5kw.
It definetly appears to be solely due to the Ergon PF of 0.9 preventing 10% of the rated output not being provided.
The best analogy I can think of would be if all the state transport departments demanded that all new vehicles be re-programmed to produce only 90% of their specified power on a pretext of making the roads safer but still costing the same for fuel consumption.
That may be in your circumstance. For Choice community readers in other states or locations I added the alternate information. They may not have the power factor limitation, but still need to look for other explanations of observed reduced output. It was convenient to draw attention to the Sungrow example.
To demonstrate it is not a unique situation One Fronius product advertised by one retailer as a 5,000W inverter contradicts the rating when you go to the data sheet and note it is rated at only 4,600W if it is the Australian model. Buyers need to look past the basic specs. This is not how it is supposed to work. The technical depth required of a purchaser is more than the average consumer will reasonably have. Choice members might be the exception, as they desire to know more.
Fronius inverter advertised on an Australian suppliers online site as a 5,000W inverter.
Why donât they install low power PC type fans to these inverters as a standard. The draw would be very minimal and the air movement would be substantial enough to reduce the internal temp. How hard would it be and I imagine it wouldnât add a lot to the cost.
As an example of these fans rated at over 200 cfm see:
That or perhaps another kg or so of heatsink and fins?
The Sungrow inverters and from my observation the current model Fronius which I was also offered for our Solar have a stylish? public face. Both ranges are typically IP65 rated, hence well sealed (zero ingress) against dust and against entry of low pressure sprayed water.
Part of the sealed assembly for both is a rear/side facing heat sink with extruded fins. And for a nominal 5kVA inverter, around 150W max of heat to waste if the Euro efficiency specs are to be believed. Less than my stereo at half power!
The Fronius âActive Coolingâ design uses two cooling fans. One inside the IP65 enclosure to circulate the air internally to cool components not mounted to the heat sink. A second fan mounted in the ventilated rear compartment is used to force increased airflow across the external heat sink fins.
A similar solution already built in, as suggested
The Sungrow inverter enclosure does not extend to the rear. It relies on natural convection of airflow between the inverter and wall mounting plate to carry heat away from the heat sink, which is part of the rear frame of the inverter. Sungrow also use an internal circulating fan similar to the Fronius solution. This design option might have benefitted from a more substantial heat sink with more fin area. However the effectiveness of this solution also depends on the heat sink getting hot enough to ensure good airflow. The hotter the heat sink the greater the airflow due to convection.
Itâs worth a simple experiment for the Sungrow or other brand inverters which are sealed units and use convective external cooling. A spare pedestal fan might be one way to test this out.
Footnote:
The Sungrow nominal 5kVA and 3kVA inverters (SG5K-D and SG3K-D) are packaged in identical enclosures. Interestingly the 5 is only around $100 more expensive than the 3! The data sheet Indicates the same weight for each.
Thatâs exactly what I have! A direct wired connection via the RS 485 port to a serial to USB port on the computer. Excellent software by manufacturer shows it on screen.
Just on 2 weeks ago Essential Energy had a planned outage for our street and would not comment on what is was for. Now I have solar and my inverter would shut down every now and then and may up to 2 times a day. I have been monitoring the grid voltage since our system was installed in 2010 and that was at 5 minute intervals ( a lot of data to now). Grid voltage now only rises to around 250 instead of at times 261 and now there is no inverter shutdowns. From what I can gather people who had solar installed around me in the last year or two were frequently having there inverters shutdown more than me and my system probably had settings set higher as it was installed many years ago
Thatâs good news E4, it will be interesting to compare your next bill with previous ones at the same time of year to gain some idea of how much Essentialâs high grid voltage was costing you.
I suspect the real issue is the impact of solar residential generation on the management of the local grid. Typically a residential neighbourhood transformer serves 150 dwellings. If the solar at these dwellings pumps a lot of surplus energy into the local grid the sorts of issues discussed previously arise. Current partial âsolutionâ is to collect surplus in a residential battery. Possible solution is to develop a âneighbourhoodâ battery that acts in conjunction with the adjacent transformer with the objective of achieving neighbourhood supply and demand balance . It comes back to using control technology to assist the supply/demand balance in the local area. Not sure that such technology is available or could be cost-effective. However recent indications are that grid operators may be looking for contributions from residential solar panel owners to offset grid costs related to surplus solar generation impact on grid stability. It seems we jumped into residential solar ahead of the grid planning necessary to cope with the advent of distributed generation on a system designed for traditional centralized generation.
There is the alternative that grid planners chose not to jump in to upgrade the grid to cope better with increased local generation. It was not an inadvertent decision.
Whose head was in the sand at the time is open to debate? The regulator, distributors, generators, States and Commonwealth all have roles and are up to their proverbials in it. I wonât mention the failures of leadership in all of this any further. There are too many for a productive discussion.
Note that local generation increases are due to more than just household PV. There are now large numbers of commercial properties, schools, industrial and farm sites. These can be from 15-30 kW with minimal approval and up to several hundreds of kW. All are high powered PV 3phase systems reducing local demand or adding to local generation. Add to this Solar PV farms, wind turbines and big batteries which can be modest in output to large scale.
That is only part of the issue, as I was able to show to Ausgrid, high grid voltages were happening at night, when there could be no possible contribution from PV systems.
That said, the grid was designed for centralised, not distributed, generation, so that transformer taps were set to allow for voltage drop along the wires out to the loads at the ends of the lines. Plenty of skimping on transformer capacity and cable diameter meant that even before PV systems became popular, many rural locations suffered from voltage variations well outside reasonable limits. Brownouts and blown light bulbs were some of the symptoms.
Agreed. I think you will find that simultaneous fascination with renewables and supply system privatization resulted in disruption of traditional system planning . Unfortunate but that is where we are now. My suggestion about suburban neighbourhood batteries is simply to address local imbalances not the wider implications of commercial and rural situations.
