Are there any solar homeowners here?

Have been doing research on solar systems recently and then came across a few companies that offer zero upfront cost. Have had a chat with one of them and here's what they offer.

  1. No upfront cost
  2. Fixed monthly fee between $85 - $165. The fee is fixed for 20 years.
  3. If the solar power is used up for the day, you get charged 12.6 cents/kWh wholesale price
  4. Free full service for 20 years
  5. 10 years warranty for the battery

I'm going to do a cost comparison against the current bill. I'm new to the industry, so any advice is welcome.


  • +2

    IMO solar for a grid-tied home is never worth it (unless you spend over 30k for enough panels to be self-reliant in city living. The ROI Is far greater for off-grid homes). In those 20 years, more efficient panels would come to market as well as new batteries. Also, I know of one company with no upfront cost but if you decide to sell the house, the new owners would have to sign up to your solar contract.

    In winter your panels would be getting around 3-4 hours of sunlight and in summer it would be around 8-9 hours of sunlight so in winter time you'd be paying the wholesale electricity prices often.
    Things like running air conditioning, charging electric vehicles, running a dryer, the heater, electric stove (if you aren't using gas), using wired tools all draw quite a lot of power.

    If you are also thinking of using batteries, depending on the type of battery, if you accidentally drain it below say 20% for deep cycle AGM, you damage the battery permanently however, lithium iron phosphate and lithium-ion batteries are more forgiving if you accidentally drain them too much.

    I use to work at a solar place :)

  • +1

    This has been previously asked and answered here

  • +2

    A 20 years contract? Nope

  • Thank you guys for all the input. I think I will not go ahead with Solar Zero. I was also looking at Aliexpress but could hardly find any products that meet the NZ standards.

    Solar panels must meet AS/NZS 5033 standards and must have IEC 61730 certification.
    The inverter of the solar power system must meet AS 4777.1 standards.

  • +1

    Ive got solar, feel free to ping me if you have any question. Ive looked at solar zero as well (to expand my system), but the ROI just isnt there

    • Thank you. Which company are you currently with and are you happy with the system?

      • Ours was part of a new build, but the panels and inverter are from Solarpartners. They were fine to deal with, and install was smooth (noting it was a new build, so probably a bit easier). If I had my time again, I would go for more panels. My issue now is that they dont make these panels any more, and splitting two types of panels into one inverter isnt an option.

        • I'm building my house next year. My plan is to get the roof covered with as many panels as possible if the cost is affordable. I'll keep looking around. Thanks!

          • @xsolider: Hi xsoldier,

            Would you be able to share your calculations for the return you will be making?

            A lot of people are saying it is not that good, whereas you appear to be saying it is.

            I appreciate you may not know all the figures accurately yet, but just what you have so far would be great.



            • @Alan6984: Australia have a fantastic government solar subsidy, which makes adding solar a no-brainer. Sadly here, its not as enticing, and I think only slightly better than break even. We only have a small system (4.3Kw) but having had solar for 3-4 years now, I have found that the best return is to get as close to 100% utilisation as possible. For that, adding the Hot water cylinder, and high throughput appliances is the best (we have HWC, pool pump and heatpumps connected to the circuit).
              Early on, we were pushing 300kw+ back to the grid, and getting the measly 8c/KW (ish) in return. Now I try to keep our buyback down to 80-100Kw, which I basically look at as a "discount' on the normal powerbill.
              If you combine it with the Contact good nights (even with the price increase), you can really get on top of it nicely.

              • @Elvino: Do you have actual numbers that show the upfront costs, the ongoing costs, and the ongoing benefits, that tell you whether you are actually getting a return?

                If so, are you willing to share them?



                • @Alan6984: I do, Ill have to dig them out. Happy to share them. For me, it was packaged in with the build, so the cost isnt the 'real' RRP cost.
                  At the time, I remember estimating a 10-11 year ROI based on what I assumed would be my usage over the period.

              • @Elvino: That's a good idea. Solar system + the Good nights plan.

              • @Elvino: what about with octopus energy - their buy back rate is higher than the off peak / night rate in many places.

                • @razza: I can’t get octopus in my area unfortunately, so haven’t investigated further

            • @Alan6984: I've only had one quote so far (for a non battery system). Is this what you're after?

              • @xsolider: Do you have actual numbers (your own best guesses are fine) that show the upfront costs (might be zero for this / some options), the ongoing costs, and the ongoing benefits, that tell you what return you would actually be getting (rather than their marketing 'estimate')?

                • @Alan6984: The upfront cost is $18690 as shown in the image. Should be no other ongoing cost when the system is under warranty. I haven't gone too deep so just used their estimated ROI. I've been looking for some oversea suppliers to bring the cost down but haven't got much luck yet.

  • I was looking at buying a house that had a solar contract on it. Think it still had over 10-15 years remaining. It put me off buying it. IMO people selling are better to pay it off. PV should have come down in price a lot more in NZ IMO.

  • +3

    I've had solar for over a year now, paid upfront and added it to our mortgage. My system has 6.5kWp of panels coupled with a 5kW inverter.
    The total cost was around 15k, which I admit is not the cheapest. At the time, I decided to go for it, not based on the payback period, but on being able to have a zero/positive net cash flow based on it being funded by our mortgage. Any increase in mortgage payments would be more than offset by the savings from my electricity bill. So, at worst, we would be no worse off than we were before, and any extra savings would be a bonus.
    Before solar, my bill used to be in the range of 2.7k per annum. I stayed with the same electricity provider for the first year, and I have saved around 1.2k in electricity bills and paid $900 in additional mortgage payments to cover the solar PV installation. So, in year one, I ended with a positive net cash flow of around $300.
    I have since switched to Octopus for electricity, and this is because of their higher feed in tariff, half priced night rates and zero daily charge for low users. Based on the modelling I did using my power consumption and solar export data, for the same period last year, with Octopus, my power bill for the year would have been $620, instead of the 1.5k I paid to my previous power company. There is no guarantee that Octopus will keep their rates. But based on the current rates, I am looking at a payback period of 7 years, which is rather good.

    We use induction for cooking, and bottled gas for hot water. If we had a hot water cylinder, we could have improved the savings by using a solar diverter to heat the water instead of exporting to the grid, and thereby avoiding the cost of gas for heating.

    I work from home, and while we try and shift some of the electricity load to sunshine hours, we are not very diligent in doing so. The reality is that we end up exporting over 50% of our generation back to the grid.

    • Hi Dennis,

      Probably a silly question, but if you have 6.5kW of panels, why do you only have a 5kW inverter?

      It sounds like you are 'losing' 1.5kW (23% or so) of the power (at least some of the time)?



      • +1

        There are a few reasons to do so, but for us it was about stretching the generation hours longer during the day. We have two strings of panels, one string north facing and the other one west facing. The north facing panels help with early morning and daytime generation, while the west string help with afternoon and evening (during summer) generation. The shape of our roof meant that we could not have all our panels in a north facing orientation.

        The other reason is to compensate for the panel degradation. Solar panels lose around 2% of their generation efficiency in the first year alone. And around 0.5% every year afterwards.
        So, if you install 5kW panels with a 5kW inverter, after the first year, the maximum output the panels can generate is only 4.9kW and that keeps reducing every year. By oversizing, we can make sure that we use the inverter more effectively and always generate the maximum output it can. Most inverters are capable of 133% panel oversizing.

        Here is a blog post with lot more details if you are keen for a read:

        • Thank you!

      • It's pretty typical. Family members system is set up like that. There are two big reasons:

        • Lines company export limits: Some lines companies restrict the maximum output to the grid. A cheap and way to do this is is to just size the inverter to match that limit. (alternately at higher cost you can a bigger inverter and a current transducer which measures the power consumption in your house, and dials back the inverter output so it's output, less the houses consumption never exceeds the max output limit).

        • Economics. It takes near-perfect conditions for panels to generate their rated output (Sun near perpendicular to panel, clean panels, no clouds etc). Conditions that only occur for a few dozen hours a year. Also note that panels degrade over time, in 25 years you would only expect 80% of the output of then the panel was new. Combine all this, and it means that if there is the roofspace available it is often better to spend money on more panels (which will add output at the start & end of the day, and most of the day in winter), than it is to spend it on a bigger inverter (to capture the peak in the middle of good weather days).

        On my family members system, in summer, you can see hot the top of the output (sine curve shaped) is cropped for perhaps 3 hours in the middle of summer days. But in summer the system is making great output anyway, and even then you can see dips below the crop line when clouds pass.

  • +2

    We got a $10k solar system through Harrisons about a year and a half ago. We'd calculated that it'd pay itself off after 7 years, but it's looking closer to 8 or 9 years, with panels that are rated for a 25 year lifetime.. Still not bad. The Fronius app tells us we've "earned" (ie not paid for as well as sold back to the grid) about $2000

    Some other points to consider that might not be mentioned above:
    * the kW rating is for full sun, so getting more panels than what the inverter is rated for, still allows you to get enough power during cloudier days without needing to pay more for a bigger inverter
    * hunt around for different power companies and their wildly different buy back rates. eg switching to Octopus for their 12c buy back (although I'm with Powershop with 8c but for cheaper night rates when I need to pay for power)
    * your bank may offer zero/lower interest rates if you put the panels on the mortgage, check it out
    * the average sales prices of house with solar vs without is higher, so even if you move home before you've paid off the panels you might still make a profit
    * it's more than just the numbers: we feel more relaxed about running the heat pump during winter and cooking during summer, rather than suffering through cold/hot days to save a few dollars

  • A good calculator here…

    I've had a 3kW solar system since 2015 and generates approx. 4,500kWh per year (Auckland, panels pointing approx. North tilted 20 degrees). The genless calculator pretty much ties up with what I see.

    I haven't seen a lot of degradation over the years since it's been installed. Maybe 4-5% total in 7 years. The panels are cleaned once per year.

  • +1

    I'm currently halfway through an install. 9kw of panels and 8.2kw inverter. Will look into adding a battery in the next few years hopefully. Was thinking of switching to octopus energy after install is done as can get 17c for export and only 16c for night rates. Gotta crunch more numbers once I have some data to go off. One thing I would say is always push for a better price on the quote. I got them down a good amount from the original quote.

  • To be absolutely fair, as a homeowner moving into 2023 I wish I could photosynthesise

  • You are providing the return on their investment, so you are never going to be better off than if you had invested that yourself.

    Solar only works out for most people if you can put enough in to cover your daytime usage, and move more usage to the daytime when it will come from the solar. If you're exporting or installing a battery then it doesn't work out. If you have a base usage of 1kw and have a shower in the morning so the water is recovering in the morning then a 2kw system will probably work out.

    Many of the calculations people do are reliant on it pushing you down into a low user consumption range, those plans that artifically subsidize low users are going away so you cant count on that to make savings.

    Many banks have low/no interest amounts able to be added to mortgage to cover solar, insulation, car chargers and other eco friendly things to get them some cred for being a sustainable bank, look at those if you can get it and see if that would swing the numbers in your favour but its always pretty close to a wash either way when I have done it now that power prices have come back a little from their worst, and that the cost of all the solar stuff has gone up with the covid shipping and dollar being worthless.

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