How to work out if your solar system is performing properly.

a ruler

Stop guessing, start measuring!

I got an email from Dec in Melbourne this week who is very worried that his solar installers have sold him a lemon:

Hi Finn, Since my last email, my 4.0kw solar has been independently checked and I have been told it was found to be installed correctly. At this time it is producing only 1800w on a clear sunny day. It seems that no one has an answer as to why the production is low as the system is only producing an average of 7.2kwh/day. Do you have any idea as to what I can do to try and resolve this as I am really struggling with getting this sorted out.

So has Dec been sold a heap of junk? Is his solar power system producing enough power for its size, location and the time of year (June) ?

How many kWh should your system produce over 1 year?

Averaged out over any one year, your system should perform to within at least 90% of these daily kWh outputs per kW installed (based on Clean Energy Council Guidelines) :

Adelaide 4.2 kWh
Alice Springs 5.0 kWh
Brisbane 4.2 kWh
Cairns 4.2 kWh
Canberra 4.3 kWh
Darwin 4.4 kWh
Hobart 3.5 kWh
Melbourne 3.6 kWh
Perth 4.4 kWh
Sydney 3.9 kWh

 

If you have had your system for more than 12 months then most good inverters should be able to tell you what your daily average has been over the past 12 months.

So if that is you – go check it! And see how your system is performing. Let us know in the comments below!

(If you don’t know how to get this information out of your inverter then give your friendly installer a call and ask them for instructions!)

But what if you have had your system for less than 12 months?

Dec, who sent me the email, has only had his system installed a couple of months. And I get the vibe that if I tell him to wait another 10 months to find out if his system is a dog he may not be thrilled with my response!

You can see why he is worried. The table says that Melbourne solar systems should get an average of 3.6kWh per day per kW installed average. So that works out at  14.4 kWh per day for Dec’s 4kW system. His last reading was 7.2kWh/day.

(If all this talk of kW and kWh is confusing you then here’s a really simple explanation of what they mean)

The thing to remember is that the table is average values over a whole year. And at the moment it is June, i.e. midwinter in Melbourne – and Dec’s panels are also facing West whereas these numbers are for optimal North facing panels.

How to check your solar power system output for any month of the year.

Here’s how we can definitively work out if Dec’s current daily reading is acceptable or not. One of my favourite tools on the web is a solar power calculator called PVWatts. It has been developed by the National Renewable Energy Laboratory (NREL) in the USA. The international version can be found here:

http://rredc.nrel.gov/solar/calculators/PVWATTS/version1/

So here’s how I used PVWatts to answer Dec’s concerns:

1. Go to PVWatts and select Melbourne as the location in the bottom RH corner:

Select your location in PVWatts

Select your nearest city.

 

2. Click to the next screen and enter the following values

a) DC Rating = 4 kW (the size of Dec’s solar power system in kW)

b) Array Tilt = 22 degrees (Dec didn’t tell me the angle of his roof – but most Aussie roofs are 18-22 degrees)

c) Array Azimuth = 270 degrees (Dec’s panels face West – this is an “azimuth angle” of 270 degrees because North = 0 degrees.

I left the other options as defaults. The “derate” factor is an estimate of the solar system losses and 77% is a little pessimistic – but will do for this calculation.

configuring PVWatts

Enter your system size, tilt angle and direction.

3. Click ‘Calculate’

And here is what we get:

PVWatts Results

The results!

The table on the RHS is showing you how many kWh per month your solar power system should produce for every month of the year. I’ve circled the column so you can’t miss it!

To translate this into a more intuitive form, I simply cut and paste the results into an Excel spreadsheet and divided the kWh/month column by 30 days to get an approximate “kWh per day” for each month of the year – along with a pretty graph for better visualisation:

the results presented in Excel

The results formatted for kWh per day per month

You can immediately see that, in Melbourne, with its miserable winters (hey – I’m from Adelaide and they stole our Grand Prix!) , there is a huge variation between power outputs throughout the year.

So for Dec’s West facing panels, right now (June)  he can expect only 4.3 kWh per day.

So good news Dec! Your system is actually performing very well based on your winter readings of over 7kWh per day!

Assuming that it can also pump out 19kWh per day when summer finally arrives, your installer is off the hook!

About Finn Peacock

I'm a Chartered Electrical Engineer, Solar and Energy Efficiency nut, dad, and founder of SolarQuotes.com.au. My last "real job" was working for the CSIRO in their renewable energy division.

Comments

  1. brian woods says:

    hi finn what u say is true as i live in bowen nth qld and with a 4kw system and having them flat on the shed roof i still get what you say

  2. This sounds like a great tool and will save me from having to do all the calcs myself. We are having our inverters installed tomorrow (2*2000kW systems) and the advantage there is that we can compare them to each other too…

    Thanks for all your hard work on this!

  3. Neil Watson says:

    Hi,

    Last summer I had a solar system fitted i.e. an 1520 watt system consisting of 8 x 190 watt panels connected to a 1700 watt SMA inverter. When the original quote was given to us it stated at a later date that the system can be upgraded by adding 2 more 190 panels. My question is would the 2 extra panels have to be connected in series and added to the original 8 panels that are connected in series and would the invertor be able to handle this set up ? OR would all the panels on the roof have to be reconfigured to 2 groups of 5 panels connected in series, and each group then connected in parallel ?

    • Hi Neil,

      To answer that question definitively I need to know the panel models and the inverter model number.

      Then I can check the specs and get back to you.

      Cheers,

      Finn

  4. Hi Finn,
    May I once again ask you another question or two?
    1. We have just installed 13 x 250W panels with a Samil Power/solar River SR3K3TLA1 Inverter with two strings per MPP tracker (2 x DC positive terminals and 2 x DC negative terminals). The 13 panel open voltage is quoted at 338V. We wish to separate the solar panel array into a ‘six’ and a ‘seven’ because the ‘six’ receives more shade from a neighbour’s pine tree. With the inverters start-up voltage at 100V, is this doable and beneficial?
    2. Our house is wired 3 phase with one 3 phase meter. The solar inverter is wired into phase 1 (or at least that’s where the 25amp circuit breaker is). We have been told that any solar power not used in phase 1 will flow over into phase 2 and then to phase 3? I am not sure that our present 3 phase meter (EDMI Atlas 2000-1010, EDY004013) will serve as a net meter for Energy Aust here in Sydney.
    Any insights would be most welcome.
    Thanks
    mike t

    • Mike, your excess power from phase 1 will definately not flow to other phases. You could try splitting your load up. Eg put your lights circuit on a phase not connected to the inverter as you probably won’t be using them whilst your producing solar power.
      With the Samil inverter you mentioned, it has 2 inputs but only one mppt. Also, your “start up” voltage rating of your inverter is very different to your “mppt voltage”.
      Regards JB

  5. graham chambers says:

    Hi Finn
    Could you advise me on the quality of the CMS2000 inverter.
    Thank You
    Graham

  6. Victor Vella says:

    Hi Finn,
    I found this string very interesting. We are just moving in to another house which faces approx 250ºW.
    AS the information I am reading all point to a North facing setup, which we don’t have, is it not possible to have an array set up on brackets of, say 45º, towards North to improve the peformance? The house is situated on the Central Coast NSW, approx 31º South.
    Thanks,
    Vic

    • Yes it is possible.

      Advantages:
      Assuming your roof angle is about 30 degrees, you’ll get 30% more power facing your panels North.

      Disadvantages:
      You usually need planning permission for racking
      It will cost quite a lot extra
      It will be damn ugly!

      How to decide:

      For every kW installed, you’ll generate 3kWh per day of electricity from the West facing panels.

      If they face north you’ll get 4kWh per day per kW installed. That’s worth about $100 per year in electricity savings. Compare that to the quote for the racking and decide if it is worth it.

      Also you may find a few extra solar panels are cheaper and more attractive than the racking!

      Finally: West may be better despite the lower power for this reason:

      http://www.solarquotes.com.au/blog/solar-panel-orientation-is-west-the-new-north/

      Hope That Helps,

      Finn

      • Victor Vella says:

        Thanks Finn,
        thats certainly worth considering & the extra panels would continue to benefit us for years to come.
        Vic

  7. Kevin McKenna says:

    Hi Finn

    Hopefully, last question. We are considering a pv system (3kw) 12 Renesola Panels and Enphase microinverters. (M215s). After asking some questions of our prospective installer here in WA (Solgain) I am disappointed to find that the readout on the enphase gateway envoy monitor only provides a readout of unit or kw hours of the whole system at any given time of the day, nothing to sat if an inverter is doing its job or not. Yes, we can purchase the MyEnlighten software direct from Enphase at a cost of $300 (so our prospective installer said), but we have to deal direct with Enphase for this and handle all of the set-up ourselves which I find daunting. Are there other (even string inverters) with better owner-diagnostic tools? Even though these panels/micro inverters have warranties of 10 years, after two years we will have to pay $65 call out fee on inverters and $165 callout on Panels. How do they get away with customer paying out during warranty periods? Also, thank you for your past responses – unfortunately the link in the message wont work for me to respond.

  8. Hi Finn,
    I had installed 12 panels with micro-invertors last year. I had someone over from AGL and connected to the meter and I see others have saved much more than me. I check nearly everyday the monitor and sometime shows tha5t is there energy but when I go to the meter , the arrow shows me that takes energy from the street, even I have just the fridge on. Other times I have tv, washing machine and PC on and the arrow id to the propriety . Is something with the solar panels or something wrong with the meter. I called AGL and they said to call United energy but I want first to ask you about it.
    Thank you

  9. Hi mate, i had a 5.0KW system installed over 12mnths ago n everything was fine, i was actually getting credits for putting power back into the grid, now my service provider,AGL(the robbing bastards) are hitting me up saying i owe them over $100 a month for power,now i live on my own in a shed with just the normal things using power,fridge,wash machine,hot water system etc, what is going on here,truly im at wits end ,can you help please,Thanks, Selwyn,

  10. Sorry forgot to add that i have 22 solar panels on this set up

  11. Praashekh B says:

    Hi Finn,
    Im planning on installing a solar system at my house and recently got a quote for solar panels and inverters for 5kw. brand named ET panels 265W, Trina Mono 290W and Canadian 260W . The ET panels are cheapest and have a free upgrade (5kw to 6kw). The company originally used GCL but now using ET till the time they have the free upgrade scheme going on.

    The inverters they wanted to use was a brand named Goodwe(they said it has a better output than SMA and similar warranty) but i asked them to Install either an SMA or Fronius.(read that you suggest a good inverter is more importnt than premium panels hence asked them). SMA is about $100 more than the Fronius.

    What panel brand should i go for? Also, this company is a relatively new (unknown) company in Perth and doesnt have many reviews.
    Is it ok to go with a company thats new and gives a better pricing than a more known company that charges higher for the same panels and inverters?

    Thank you.

    Regards and Happy New Year.

    • Hi Praashekh,

      A new company is a risk compared to more established ones with lots of good reviews. The installation is very important – perhaps see if you can inspect an existing install of theirs so you can see the tidiness of the install?

      SMA or Fronius is better than Goodwe – good call. Frionius have a 10 year warranty – they’d be my choice. ET panels are a mid-range Tier 1 panel:

      https://www.solarquotes.com.au/panels/et-solar-review.html

      All those 3 brands should be fine. If I had to choose, I’d personally go with Trina:

      https://www.solarquotes.com.au/panels/trina-review.html

      Hope That Helps,

      Finn

      • Praashekh B says:

        Hi Finn,
        Thank you so much for your reply.

        The name of this company is Perth Solar Force. Dont know if anyone has heard of it. The other ones i was recommended was EuroSolar(recommended by workmate, USG panels and SMA or Zever inverter option) and TrueValueSolar(recommended by mum-in-law, also the most expensive of the lot so far using Jinko panels and Bosch inverter) .

        The price difference between Euro and TrueValue is about $200. (5200-5400) . PerthSolar is quoting 4300 (Fronius + Et panels) . Fronius and Qcell goes more expensive than the other companies.
        The Trina panels they are providing are Monocrystalline panels hence i wasnt sure if i should go for it as the seller recommends Polycrystalline for Perth conditions. Would that be better than Poly?

        If i do get a chance to visit a property by the Perth Solar guys what should i look for to know the installation job is done well? Or not done well?

        Thank you

        Praashekh

  12. Hi Finn,

    This is an excellent site! Our next door neighbour had a solar system installed last week, and is pretty happy with the service, so we asked them to come and give us a quote. We’ve been wanting to get solar panels for ages but as pensioners we are very wary about spending heaps of money that will take forever to justify itself, so this was a good opportunity to find out what we’d be up for. The company is Aztech Solar and they recommended a 5kw system using 20 panels, with 12 located on the side of the roof that faces approx north, and 8 on the side that faces approx west. I see that both the solar panels they use (GCL), and the inverter (Goodwe) are on the lower end of the scale going by your research, so now we’re a bit concerned about reliability. Anyway have filled out your form to get some more quotes so will take it from there. One thing we need your expert opinion on is that we’re not sure how a solar system will work with our three phase power, and if Ausgrid will have to come out to reconfigure it. At the moment it looks as if our ducted aircon is actually spread out over the three phases. Is this likely? And the pool pump looks as if it just uses one phase. Would it be possible to run both these things on a 5kw solar system? We live in Cessnock in the Hunter Valley and gets LOTS of sun!
    Look forward to your advice. Thanks.

    • Ronald Brakels says:

      Hello Gail, Ronald here. Glad to hear you’re looking at rooftop solar. Once you get your quotes, if you have any questions, please feel free to ask.

      Homes with 3 phase power can use 3 phase solar inverters or single phase inverters. They are both okay. If you are getting a solar system with a 5 kilowatt or smaller inverter, single phase will be fine.

      Ducted air conditioners are often 3 phase and so it is normal for them to be spread over 3 phases. And pool pumps are often single phase and so only use one phase. If you get a solar system with a single phase inverter your installer will place it on which ever phase should be most suitable for your home.

      You can run both a three phase air conditioner and a single phase pump with rooftop solar that has a single phase inverter. Your meter will only count the net amount of electricity going into and out of the house. So if one phase is sending 2 kilowatts of solar electricity into the grid and the other two phases are each drawing 1 kilowatt from the grid, as far as your electricity meter is concerned, you are not using any grid electricity at that time.

      • Hi Ronald, thanks for that, I THINK I understand re the 3 phase thing! Basically I need a good installer to tell me which phase is drawing the most power, and feed the solar power into that, is that kind of on the right track? Because I guess there’s no way we could generate enough power to run the whole house, without covering the entire roof and spending a fortune.
        On another note, I have received an email from your website asking me to complete the request form so I can start getting quotes, but I though I had completed it and anyway have already had an email from a solar power company in Denman. So should I fill out the form again? Thanks!

        • Ronald Brakels says:

          Yes, that’s that right track. Your installer will sort it out for you.

          As for how much electricity you can generate, in Cessnock you can expect to produce an average of nearly 4 kilowatt-hours a day per kilowatt of solar panels. So with 5 kilowatts of solar panels you should average nearly 20 kilowatt-hours a day, while with 3 kilowatts you should average nearly 12 kilowatt-hours a day. That’s for north facing panels. Panels that face east or west will make about 14% less.

          I don’t know why you were asked to fill the form in again. Don’t bother doing it again, it should be fine, but I will look into it just in case.

        • Ronald Brakels says:

          I checked and everything is fine, Gail. There’s no need to fill the form a second time. Sorry it got sent to you twice.

  13. phil mortimer {0409710059 } says:

    IN, WE HAVE ATTEMPTED TO GO TO THE SITE GOV/ SOLAR CALSULATORS, ,UNABLE TO ACCESS, JUST HAD SOLAR INSTALLED 4.4 SYSTEM.16 PANELS, 20TH /NOV/2016, {NOW WITH MOJO POWER} PREVIOUSLY QUARTERLEY BILL AVERAGE $170, MOJO FIRST BILL $208, AS OUR METER GOES IN REVERSE OR AT LEAST EIGHT HOURS A DAY, DONT APPEAR TO BE SAVING ANYTHING AND COSTING MORE ,ANY SUGGESTIONS ,THANKS PHIL{ SYDNEY}

    • Ronald Brakels says:

      Phil, if your meter is going in reverse then it sounds like you haven’t had your old spinning disk analog meter replaced with a digital import/export meter yet. I would have expected it to be done by now, but in NSW the people changing meters are very busy at the moment, so that might explain the delay.

      But don’t worry, your meter going backwards is a much better deal than getting a feed-in tariff, so enjoy it while it lasts. But it is probably a good idea to look into when you are getting your meter changed as you are required to have an import/export meter with a rooftop solar system and there is no point in getting in trouble because someone overlooked installing yours.

      You solar system should be saving you money on your electricity bill and the fact that your meter runs backwards is proof that it works. However, if you’ve just changed to Mojo you may not be able to directly compare your new electricity bill to your old one as Mojo charges a fairly hefty annual membership fee and I’m not sure how they apply that to bills. Because of this yearly fee Mojo is often not the best choice for small users of grid electricity, which includes the many solar households.

  14. Can you tel me if my inverters have stops working dose that mean my electricity that I get paide for stops generating i have only had my solo panels up just over 1year and the inverters have stops working

    • Ronald Brakels says:

      Hello Sarah. If your inverter stops working your solar panels will no longer produce any electricity so you won’t be paid for sending electricity into the grid. The good news is your inverter should have a 5 year warranty, so you can call your installer to arrange a replacement.

  15. Greg Baker says:

    Hi Finn
    Hope you can help
    I have a 5.5KW (22 pannels X 250W) connected to a SUN 5KW inverter on single phase.
    I want to add further solar panels ( 5KW ) + battery’s to the system to further reduce our bill.
    Is it permitable to add this to a single phase, if not what can be done to allow this.

    Thanks
    Greg

    • SMA not Sun Inverter

    • Ronald Brakels says:

      Hello Greg, Ronald here.

      What you are likely to be allowed to do will depend on where you are and who your Distributed Network Service Provider (DNSP) is. In some places you may be allowed to do as you plan, in Queensland they would expect you to be export limited to 5 kilowatts and use DC coupled batteries, and in too many places they are likely to just say no.

  16. Hi Ronald
    Thanks for the answer, I am in NSW on Energy Australia how will I fair with them and if the answer is no should I look for a preferred provider.
    Thanks’Greg

    • Ronald Brakels says:

      Hi Greg.

      Energy Australia is your electricity retailer, but your DNSP is different. In Eastern Sydney and up to Newcastle it will be Ausgrid. In Western Sydney out to the Blue Mountains it will be Endeavour. And in Rural NSW it will be Essential Energy. They are the ones who will determine how much you can install and it’s not possible to change them unless you change address. In rural NSW you may be able to do what you want but you are likely to be required to export limit your system, while in other areas there is a good chance you will be denied permission.

  17. michael cullen says:

    hi there, i read somewhere that there is a company that will come out and check you system to make sure it is working to its capacity, i live in adelaide, can anyone help out?

  18. Hi Finn

    I am in a process of contacting solar installing companies and came across one named “Driftwind Electrical” mainly operating in QLD. Could you please advise whether you know anything about this company. I am unable to find it on the Clean Energy Council’s list of certified installers in QLD. Could you please assist. Thank you
    Ved

  19. Hi Finn

    I got a quote for a 4.5kW QCells panels 17 X 270W and a Fronius Inverter for about $5,500 (special price?). On top of this I will add $1,800 to convert my current hot water (gas) into electrical hot water system. Could you kindly advise whether this would be worthy taking up this offer. thank you.
    Vedaste

    • Ronald Brakels says:

      Hello Vedaste

      QCells are tier one panels that have a 12 year product warranty and so definitely should be reliable. Fronius inverters have a good reputation for reliability and come with a 10 year warranty. But note only the first 5 years is for full replacement. In the second 5 years of the warranty they will provide a replacement inverter if required, but won’t cover the cost of installation.

      $5,500 for 4.5 kilowatts of panels comes to $1.22 per watt, which isn’t bad for a system with quality panels and inverter that is installed well. There is a good chance the cost per watt for a larger system would be even lower.

      I can’t be certain getting an electric hot water system will be worthwhile for you, but if it enables you get rid of gas entirely, then it could definitely be economically worthwhile due to the high fixed costs of having gas. If you are planning to keep gas then it becomes harder to say if it will save you money.

      • Hi Ronald
        Thank you very much for your prompt reply. You have provided important and helpful explanations. Much appreciated.
        With regard to connecting my hot water to solar system the salesperson assured me that the 4.5 kW system will be able to generate enough solar energy to run hot water with a minimum of about 14kWh per day. Of course, I am still a bit concerned about whether the system will be able to provide enough hot water early mornings (5.30am – 7am) where 5 people will need shower. Any further thought about this? Thank you.
        Regards
        Vedaste

        • Ronald Brakels says:

          Hello again Vedaste.

          In Australia rooftop solar can be expected to generate an average of around 4 kilowatt-hours a day per kilowatt of panels. So it is possible a 4.5 kilowatt system could produce an average of 14 kilowatt-hours a day even in June, which is the worst month for solar. But the problem is, it is difficult to make sure that surplus electricity is used to heat water.

          It is possible to put the hot water system on a timer so it will turn on when the sun is shining, but because this will usually result in grid electricity being used as well as solar electricity it can be cheaper to have an electric hot water system on a controlled load (also called an economy tariff). I wrote about this here:

          https://www.solarquotes.com.au/blog/solar-hot-water-timer/

          It is also possible to use a device called a diverter to send surplus solar electricity to an electric hot water system, and I wrote about them here:

          https://www.solarquotes.com.au/blog/solar-hot-water-diverters-vs-batteries/

          And I will soon publish more information on them, but often households will be better off spending the money on getting a larger solar system, particularly now that electricity prices are so high and feed-in tariffs have increased for most Australians.

          So, if you are going to go ahead and get an electric hot water system, I suggest looking at the cost of using a controlled load to heat your water and the feed-in tariff you are likely to receive for surplus solar electricity you send into the grid. If your feed-in tariff is more than what you will pay for a controlled load then there is no point in attempting to use solar electricity to heat water and you may as well use a controlled load.

        • Ronald Brakels says:

          I should have also mentioned it is possible to use a Fronius relay and smart meter to turn on an electric hot water system when there is sufficient surplus solar power for it. I wrote about this here:

          https://www.solarquotes.com.au/blog/using-fronius-inverter-smart-meter-relay-make-solar-electric-hot-water/

  20. Is there a person that I can hire to check my solar is working properly?

  21. William Pang says:

    Hi,

    I had my solar system installed 2 days ago and yesterday reading was incredibly high. My monitor records my system produced 77.85 kWh on 28th Nov 2017. Is seems impossible that my system is able to produced that much in a single day. (Confirm its single day production, not cumulative over several days). Also the system was installed on 27th Nov 2017.

    Inverter – Solaredge SE5000 HD-Wave
    x19 REC Twinpeak2 285W = 5.4KW
    Location – Melbourne

    Here’s the link to my system
    https://monitoringpublic.solaredge.com/solaredge-web/p/site/public?name=Wantirna VIC AU#/dashboard

    • William says:

      Hi Finn,

      Finally the installer returned & got it to work properly. My Soleredge monitor is displaying the correct Consumption, Solar Production & Self Consumption. With Solaredge I can output the daily stats by 15 mins interval to excel. However the results are in W. How do I convert the value from W to kWh?

      Example
      Date Time 24/02/2018 11:00am
      Consumption (W) = 344.337

      I found somewhere it says E(kWh) = P(W) × t(hr) / 1000. So is calculation correct?

      344.337 x 0.25 / 1000 = 0.086

      • Yes, you are outputting x Watts for quarter of an hour. So you divide by 4 to get Wh (watt-hours). Then to convert it to kWh (kilowatt-hours) you divide by 1000, because 1kWh = 1000Wh.

    • Finn Admin says:

      Looking at the daily power curve – it looks correct – which tells me that your system monitoring hardware appears to be installed correctly. But the energy calculation is way off – like 4-5x too high.

      I would wait until December – it may sort itself out.

      If the problem continues on 1 Dec there is a software configuration issue that your installer needs to fix.

  22. Hi Finn,
    I have a 3 kW solar system which is working normally.
    We are a family of 3 without a pool. We are using on average 31 kWh of power every day according to our power bill.
    All lights are led. We have a gas top stove. We aren’t home much of the day because we all work. Our air conditioning isn’t used very often.
    I can’t work out where all the power is going. Any ideas or suggestions.
    Your help would be greatly appreciated.

    • Ronald Brakels says:

      Hello Paul, Ronald here.

      I presume your solar system isn’t new and you can see from your bill that it is feeding surplus solar electricity into the grid which you are receiving a feed-in tariff for. If that’s the case, we can be confident the problem isn’t there.

      There are a number of things that could be contributing to a high electricity bill. It is not uncommon for people to overlook electricity use. The most common being space heaters and hot water, both of which chew through a lot of energy. But if your water heating is gas as well as your stove then that’s not it. But leaving a 1.5 kilowatt fan or bar heater on overnight for 10 hours will consume 15 kilowatt-hours of electricity. Some people leave electric blankets on at all times and that also adds up. Most modern TVs are surprising energy efficient, but it’s possible you have one that’s an energy hog. One way to tell is if it gives off a lot of heat. It should also have its wattage on the back or you can look it up online.

      If it’s not electricity consumption that has been overlooked then you may have a faulty system somewhere. For example, a friend had a huge electricity bill and it was the result of a leaking hot water system. Defective fridges that don’t cool properly and run all the time can also chew through several extra kilowatt-hours through a day.

      You can go around disconnecting things and seeing what effect that has on your electricity consumption. Or you may find installing energy monitoring equipment is more convenient.

      • paul oddy says:

        Hi Ronald,
        Thanks for your reply.
        we have solar water heating. Our fridge is quite new and seems to be working properly. I cant remember the last time we used a heater in the house.
        One of the many benefits of living in Qld . We have three phase power connected to the house due to our air conditioner. Which isnt used most of the year. Is it possible that the phase connected to the solar and the house is not where most of the power is being used. That is. its being used on the other two phases. So effectively the solar is having no effect on power used on the other two phases. Your thoughts/suggestions would be most appreciated.

        Regards

        Paul Oddy

        • Ronald Brakels says:

          Hello again.

          It won’t be the phase the solar is on because a three phase import export meter only records the net amount of grid electricity used by the house. If the phase the solar is on is exporting 4 kilowatts to the grid while the other two phases are importing a total of 4 kilowatts from the grid, as far as the meter is concerned the home isn’t using any grid electricity.

          But what it could be, I don’t know. Tracking your electricity use by checking your electricity meter every couple of hours and making notes of consumption is an option. This can help you identify either when the drain occurs or if it is steady. This might be enough to figure out what the problem is.

  23. Hi Finn,
    I have been having an intermittent problem with my system (SMA 3kW inverter, 3kW Trina panels on 2 strings)since May. On some rainy days and on some cloudy days I get an error 35 Insulation Resist/Check Generator. The trouble appears related to the ‘West’ string, if I shut down the DC isolator, the inverter connects to the grid, then I tern the ‘West’ string back on, no problems.
    I have had 2 electricians out to inspect, the first charged $50, the second charged $400. Both reported they cannot find a problem with the ‘West’ string. But the second electrician said there was a fault with the inverter,. He measured 4 ohm resistance on the DC side of the inverter +ve to earth and -ve to earth on both strings. I contacted SMA in Sydney and they responded by saying that the findings of the reported error were not relevant and to check the arrays again (they noted that it could prove difficult to find the earth fault)
    So where do I go from here? can you give me some feedback to the question about faulty SMA inverter? and give me a suggestion of a knowledgeable service technician available in Brisbane.

    • Hi Finn and others,
      I got my answers to both questions. The company that sent out the second Electrian sent out a more senior electrician at no cost. In 20 minutes he identified that both strings were problematic and 3 panels were causing issues. He removed the faulty panels and moved panels to allow for only one active string. No more error 35 and no concerns with the inverter. Im just waiting for his report to send to Trina for a warranty replacement.

  24. Hi Finn,
    I have 9×250 panels facing North on a Solax 2 KW inverter what should it be producing per day in April . Many thanks hope to hear from you soon.Regards William

    • Ronald Brakels says:

      Hello William, Ronald here.

      Your 9 panels total 2.25 kilowatts so at noon on a clear day you might it to produce around 1.8 kilowatts. That’s assuming typical losses. Don’t be shocked if it’s a little lower and if it’s higher, that’s good.

      If you want to know the actual daily average for April the PVWatts site will be able to give you a figure for your general area. Note that the results tend to be a little higher than what most people get:

      https://pvwatts.nrel.gov/

  25. Kerrie Spencer says:

    Hi Finn,
    I had a 5.3KW solar system comprising 19 X 285W Canadian Solar panels and Enphase 270W Micro Inverters installed in April. Consumption since has jumped dramatically every day. My average daily consumption according to energy bills over past 5 years ranges from 22 to 32 KW per day. Now according to the Energy Australia monitoring site my usage ranges from 30 to 61KW per day, with the majority of days being mid 30’s to high 40’s. The highest usage periods on nearly every day is between midnight and 4 to 6am where I am drawing 5 to 6 KW per hour.
    The installer has checked wiring and says its OK. The system monitoring shows it is producing up to 20 KW on sunny days so my daytime consumption from the grid is nil on those days.My usage has not increased as I have been aware of new readings so I am too scared to use heaters etc. Energy Australia have fobbed me off as I haven’t yet received a bill to dispute. Can you give me any advice as to what the problem might be or who I can get to help.

    • Ronald Brakels says:

      Hello Kerrie, Ronald here.

      It is possible the Energy Australia monitoring site is incorrect. You can check this by reading your electricity meter and seeing if it says you are using large amounts of grid electricity. If it doesn’t say you are then you are fine as your meter is recording the correct amount. If it does say you are using large amounts of grid electricity and your are confident the wiring is okay then it is possible you have an appliance that is consuming a lot of power. A friend of mine received huge electricity bills because of a leaking hot water system and an ex-wife had a huge electricity bill because a child decided to leave a bar heater on in her room at all times. You can try to track the problem down by turning things off at a time your electricity meter says you are consuming a lot of electricity.

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