Solar options for home in 2022.

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#3213880 3-Apr-2024 20:13

Jase2985:
Mercury had a great buyback offer of 18c but only on the first 500kWh per month
EK and Octopus had 3 different tariffs
Genesis had 50% off night rates + take your night rate with you to chargenet stations.
Meridian had the lowest daily charge (at least55c lower than the rest) and almost the lowest day/night rates

Just to mess up your spreadsheet even more, if you're running a full ESS rather than solar-only you also need to consider providers with free power plans since you can charge your batteries during the day, run from them in the evening, then refill them on free power overnight.

Also, any plan you choose will be changed by the provider two weeks after you sign up for it :-).

Jase2985

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#3213900 3-Apr-2024 20:51

HarmLessSolutions:

Jase2985:

@HarmLessSolutions i did factor 12kWh per day for charging, which is probably on the high side, but i have only had the car for a week so need to work that out once i go back to work next week. We have a heated swimming pool which will use 3kWh during the time its running, so thats something we can use to stop the inverter clipping, and our base load is about 1kWh.

Its probably going to take a bit of playing round to see what works.

Fair comment. If you estimate your EV charging requirements on 5km/kWh you shouldn't be too far off the mark, and your swimming pool strategy for 'soaking up' excess generation makes sense.

IMO it's probably wise not to commit to long term supply agreements (e.g. Meridian's 5 year solar) until you gain some real life experience in how your lifestyle dictates your requirements.

The meridian EV plan is only 2 years, and the longer plans didnt factor in due to the higher peak/off peak rates.

WolfmanNZ

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#3214717 5-Apr-2024 16:41

I just came off first 12 month contract with Octopus. Rates have now gone up including daily rate and solar buyback has dropped to 15c. Looking at the Poweredge offer atm for the 20c buyback - 5 year fixed deal. The day rate is decent (for Manawatu) and not going up for 5 years is appealing - I doubt its going to get cheaper! But the night rate is stupid high, and given we are looking to add batteries that would be most likely charged overnight during winter, its a bit of a problematic decision.

HarmLessSolutions

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#3214726 5-Apr-2024 17:05

WolfmanNZ:

I just came off first 12 month contract with Octopus. Rates have now gone up including daily rate and solar buyback has dropped to 15c. Looking at the Poweredge offer atm for the 20c buyback - 5 year fixed deal. The day rate is decent (for Manawatu) and not going up for 5 years is appealing - I doubt its going to get cheaper! But the night rate is stupid high, and given we are looking to add batteries that would be most likely charged overnight during winter, its a bit of a problematic decision.

I received this quote from Meridian for their Solar plan, Low User option (in Taranaki):

Just gathering info for when our Octopus 12 months fixed ends later this year. Like you @WolfmanNZ got from Poweredge there is no lower 'off peak' rate which for us means that on the odd occasion that we need to charge one of our EVs at night rather than from our solar (more likely in winter) it will be at a rate that is virtually the same as our current Octopus shoulder rate. Daily fixed charge is reasonably low but not enough to make up for the lower overnight (off peak) rate of 18c that we get from Octopus.

The Meridian EV plan rates that were posted above has a decent off peak rate but is offset by a big drop in the FIT.

The electricity supply landscape is changing fast though with some favourable reports coming out about Octopus's Agile plan that is available in the UK which allows Octopus to control a customer's consumption in order to benefit from the ups and downs of the wholesale electricity market. Think we'll be waiting and watching for the next 6 months and see what turns up.

https://www.harmlesssolutions.co.nz/

tweake

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#3214735 5-Apr-2024 17:18

HarmLessSolutions:

I received this quote from Meridian for their Solar plan, Low User option

small thing, low user options are being phased out. mine has already gone (genesis) and got an increase in the bill.

HarmLessSolutions

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#3214746 5-Apr-2024 17:22

tweake:

HarmLessSolutions:

I received this quote from Meridian for their Solar plan, Low User option

small thing, low user options are being phased out. mine has already gone (genesis) and got an increase in the bill.

Maybe worth tying Meridian into a quote that has an advantageous low user plan for 5 years in that case then, if it suited your usage model?

https://www.harmlesssolutions.co.nz/

EgorNZ

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#3215687 8-Apr-2024 14:35

I recently got a solar+battery system from Harrisons Solar installed on my house. Originally ordered in September last year, but multiple shipping delays meant the panels took a long time to arrive and install didn't happen until March, I guess that was out of their control though. Overall they've been good to deal with and the gear all looks great (JA panels, Fronius Primo Gen24 inverter, Tesla Powerwall 2 battery).

Pleased to say I'm already seeing a big drop in grid power consumption since the system was turned on. We're with Contact Energy on the "Good Nights" plan which gives free power from 9pm-12am every day, so together with the battery we've been able to shift almost all of our usage on most days to either be direct solar, stored energy, or free from the grid.

But I have a question about how much output should be expected from a solar power system. My install consists of 24 x 420W panels, which works out to a rated max power of 10.08 kW at STC. The inverter is rated at 8.0 kW. So my expectation was that, at 12:00pm on a clear sunny day the system could be generating up to 8.0 kW. Of course, it would be less in the morning or afternoon, and if there's any cloud cover.

The panels are all installed on a single run of roof at a pitch of 45deg and north facing (bearing ~350deg). There's no issue with shade on the panels. According to Niwa SolarView my location in Hibiscus Coast with panels in this orientation should get up to 1017 W/m2 at midday on a cloudless day in April.

Yet so far the peak output I have seen is under 6 kW, even in what seems like ideal conditions. I am in discussion with the installer about this, but if there's any experts here I would be interested to understand whether this sounds like a fault with the install, or whether it's just my expectations that are wrong?

HarmLessSolutions

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#3215691 8-Apr-2024 14:56

@EgorNZ Your setup is pretty similar to ours which is optimally angled facing north, 9.5kW of panels into an 8.2kW Fronius inverter. We have no battery in our system but have diversion in place to the HWC and Evnex EVSE. We have our system connected to a single phase so have a 5kW export cap which is complied with by inverter throttling based on monitored export.

Your generation should be reaching 8kW for a good portion of the day as the 'surplus' of panel capacity will be reaching the inverter's max output by mid morning until mid afternoon. My initial suspicion is that you're seeing generation less whatever consumption you've got happening at the time (e.g. battery charging, home use, etc.) rather than total generation.

The following screenshot is our generation data on a near perfect day with HWC diversion initially, then 5kW throttling before and after connection of our 7kW EVSE. As you can see our 8.2kW inverter limit holds for a good period over the middle of the day. You should be able to interrogate a similar data set from your own Fronius as the screenshot is from our own Fronius's monitoring. Your own generation total shouldn't be far short of the 62kWh stated on our data, allowing of course for the less optimum sun aspect and duration for mid April. We are now seeing daily total generation in the low 50s.

https://www.harmlesssolutions.co.nz/

EgorNZ

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#3215697 8-Apr-2024 15:13

@HarmLessSolutions - here's an equivalent chart of my system performance yesterday from the Fronius. My consumption looks a little different to yours because for the first couple of hours all the solar is going into the battery, and then the surplus is exported from around 11am. It was a generally fine day with some cloudy periods so the output was spikier than your January example but you can clearly see how the levels top out below 6kW. (And how we cranked up the heatpump at 9pm, haha)

Consumption from the battery is invisible to the Fronius, but the Tesla app provides a similar kind of monitoring system which paints a similar picture so I'm pretty confident with my interpretation of the data.

The performance of your system is more like what I was expecting from mine, so that's good validation, thanks!

HarmLessSolutions

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#3215701 8-Apr-2024 15:28

@EgorNZ There's definitely something amiss in your setup as you should be seeing a few hours of 8kW generation each day when sun conditions are optimum. Your Powerwall consumption is similar to our Paladin diversion to the HWC so I can see past that. It would be interesting to see your data for a 'good sun day' which should show a bell curve of generation.

Are you able to perhaps drill down into your Fronius data to individual arrays? Go into analysis/History/Channels (select Current DC MPP1/2) and select OK to activate them. The different arrays, assuming you have 2 or more, should mimic one another within reason.

https://www.harmlesssolutions.co.nz/

EgorNZ

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#3215710 8-Apr-2024 15:46

@HarmLessSolutions

I'm not sure how the panels are arranged into arrays. Physically, they're laid out in a row of 14 on top and a row of 10 below, if that means anything.

Here's the MPP data for yesterday, the channels do appear to track along in sync most of the time, but with MPP2 being about 60% the magnitude of MPP1.

However some days look weird?

wongtop

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#3215730 8-Apr-2024 16:26

@EgorNZ - do you have the AC voltage monitored? I wonder if it is clipping because of high AC voltage. Does the inverter report MPP DC voltages as well as the DC currents - if the DC voltage goes up when the DC current goes down then it could be the inverter clipping for some reason - if the voltage stays the same or drops - could be shading, clouds, etc.

neb

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#3215744 8-Apr-2024 16:59

Related question that came up a few days ago, our HWC cycles on and off at random, at least as determined by the thermostat, including in the middle of the night when we're running off battery. So I thought of using a Shelly relay to turn off the power to it from midnight to maybe 8am so it'll either run from free 9pm-midnight power or solar during the day, but not unnecessarily heat the water from batteries at 3am.

(Insert 3-page discussion of it being a heavily insulated cylinder that doesn't lose much heat, we won't run out of hot water, and a future enhancement is to match excess solar consumption to having the HWC running, the current step is just to reduce battery drain overnight).

Can anyone see any problems with this? To wire a Shelly into the HWC power do you need an electrician or is it OK as a DIY?

EgorNZ

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#3215745 8-Apr-2024 17:00

@wongtop Here's the chart again with the voltage and current. The AC voltage looks flat throughout. The MPP1 current is clipping at 22.00A, which matches the rating on the inverter, the DC voltage doesn't dip though. Meanwhile, MPP2 has high voltage and low current?

HarmLessSolutions

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#3215800 8-Apr-2024 17:32

EgorNZ:

@wongtop Here's the chart again with the voltage and current. The AC voltage looks flat throughout. The MPP1 current is clipping at 22.00A, which matches the rating on the inverter, the DC voltage doesn't dip though. Meanwhile, MPP2 has high voltage and low current?

Also the voltages from each of the arrays differs significantly which together with the amperages (which contrast inversely) suggests to me that there is an uneven split between the 2 arrays. Pulling up the comparate kW on both arrays may shed some light on this.

The grid (AC) voltage seems more stable than ours is though we're rural which is the reason here so I doubt that's an issue in your case.

I note that the amperage clips on array one it coincides with the amperage on array 2 crashes. Someone with a better knowledge of this should be able to interpret something from this dat but it's a bit beyond my pay scale.

https://www.harmlesssolutions.co.nz/

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