Solar options for home in 2022.

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16 posts

Geek

#3259583 15-Jul-2024 10:12

Egor I don't think you're comparing the numbers correctly. Your night rate is free but the other rates will be jacked up to compensate. To work out how much you're saving going to a powerwall you'd want to price it based on a regular plan since you probably wouldn't be on good nights without the battery right? Then you'd be buying off-grid at lower rate during peak-time like 22c/kWh rather than 27.7c and that makes the costs saved only $1600/yr which is still decent but it's important to be as accurate as possible with these decisions.

Dilbonius

16 posts

Geek

#3259584 15-Jul-2024 10:16

sounds like you put solar in for different reasons to the rest of us and didn't do enough research.

Did you make it clear to the installer what you wanted from the system?

I'd say I didn't quite do enough research so but I'm a busy person. The salesperson knew I have daytime loads and want ROI and I think they should have bought up the inverter size but really their interest is in making a sale first and foremost. You make me think solar is just for hippies and preppers? Wanting a good return is reasonable.

EgorNZ

50 posts

Geek

#3259585 15-Jul-2024 10:20

Dilbonius:

Egor I don't think you're comparing the numbers correctly. Your night rate is free but the other rates will be jacked up to compensate. To work out how much you're saving going to a powerwall you'd want to price it based on a regular plan since you probably wouldn't be on good nights without the battery right? Then you'd be buying off-grid at lower rate during peak-time like 22c/kWh rather than 27.7c and that makes the costs saved only $1600/yr which is still decent but it's important to be as accurate as possible with these decisions.

Not really, because with this setup we are able to arrange the vast majority of our load to either be:

Powered directly by solar during the day
Load shifted to run off the battery storage
Timed to run from the grid during the free period

So we're using a lot of energy at 0.00c and very little at the regular rate.

Edit: I guess your point about this inflating the value of a kWh in the ROI calculation is fair. But we were already using this plan before we got solar, because merely timing loads to run during the free period was saving us money despite the higher unit rate during the day - so we would be on this plan regardless.

eonsim

398 posts

Ultimate Geek

Trusted

#3259983 15-Jul-2024 20:37

EgorNZ:

On the subject of batteries - your choice of electricity plan can make a big difference to the economics.

I'm with Contact on their Good Nights plan which provides three hours of free power every night (9pm-12am), which is enough to fully recharge the Tesla Powerwall. Put that together with solar and I can pretty much bank on filling the battery twice every day for free.

The battery has a capacity of 13.5kW but I keep 25% in reserve (in case of a power outage - common here), so the usable capacity is about 10kW.

At my unit price of 27.7c/kWh, a free 20kW each day is worth $5.54. Over a year, that's roughly $2000 earned from having the battery. And if NZ power prices keep rising at 3% per year, after 5 years that 20kW will be worth $2300.

The install cost for the Powerwall was $17k, so it should pay for itself in about 8 years, in my case.

A good way to understand the value is to calculate the true cost per kWh of all your energy use (include line charges, so total bill from power company for electricity supply).

((Cost of Energy)-(Solar Export credit))/((Imported Energy kWh) + (Solar used)) = $/kWh

For example for us:

With our solar last year our effective rate was: 15.9c per kWh
If we hadn't had solar our effective rate would be: 20.1c per kWh

To calculate the second number for a system with solar or battery:

((Cost of Energy)+((Solar used + Battery used) * pkWh rate))/((Imported Energy kWh) + (Solar used))

Solar provides about 25% of our electric use, so the numbers add up.

chimera

506 posts

Ultimate Geek

#3271604 14-Aug-2024 17:50

Has anyone here with solar, bought and hooked up any lithium battery to their system that has been purchased from micromall? IF so, what inverter do you have, what micromall battery did you buy and what has been your experience?

Quinny

885 posts

Ultimate Geek

Trusted

#3271957 15-Aug-2024 11:13

EgorNZ:

On the subject of batteries - your choice of electricity plan can make a big difference to the economics.

I'm with Contact on their Good Nights plan which provides three hours of free power every night (9pm-12am), which is enough to fully recharge the Tesla Powerwall. Put that together with solar and I can pretty much bank on filling the battery twice every day for free.

The battery has a capacity of 13.5kW but I keep 25% in reserve (in case of a power outage - common here), so the usable capacity is about 10kW.

At my unit price of 27.7c/kWh, a free 20kW each day is worth $5.54. Over a year, that's roughly $2000 earned from having the battery. And if NZ power prices keep rising at 3% per year, after 5 years that 20kW will be worth $2300.

The install cost for the Powerwall was $17k, so it should pay for itself in about 8 years, in my case.

I'm in a similar situation. I've had solar panels and a Powerwall for just over three years. I recently switched to the Good Nights plan, and I'm kicking myself for not doing it sooner (I was previously with Genesis and their Power Shouts plan). The Powerwall is now on Time of Use (TOU), managing to feed in 20kWh a day and keep me completely off the grid the rest of the day. This is in August in the 20-25kWh house (excluding gas hot water/fire). I sit around 4 to 1 for free power and have to keep an eye on the 200kWh a week fair use (oops).

I keep seeing people asking about ROI and for me it has always been Self Sufficiency and Feel Good Benefit / Add to the value of the property with QV (a MUST in my opinion) / Savings. Unless you look at all things combined rather than I saved x and paid y, you short-sell it. How you pay also comes in (I used a Westpac zero-interest loan). Three years later, I feel I have saved heaps (my maths has at over 3k a year), added 40k to my property value/easier sale as it is a plus, and I have a massive feel-good when I hear people moan about 400plus power bills and I made on what I used and sold that day. But I massive time shift, I live in the apps daily, and I make sure things happen when the sun shines. I have made sure most things have time delay options and make use of them as well.

prob

225 posts

Master Geek

#3272356 16-Aug-2024 11:17

FYI my electricity company, Z Energy, buys back surplus electricity a the going market rate. As this was recently 90c a kWh, this will dramatically improve the economics of having solar..

https://www.z.co.nz/products-and-services/z-app/power-your-home/wholesale-power-rate/

billgates

4705 posts

Uber Geek

Trusted

#3272405 16-Aug-2024 11:35

The issue with the likes of Z and Flick is specifically Z that due to no contract terms they can change your per unit price with a 30 days notice. I imagine flick hedged really well against future prices and can afford to wait until April of every year to increase there retail prices but small players like Z are highly likely to increase retail prices with the 30 days notice prior to April. By then when you do want to switch to another reailer on a contract term to get lower retail price because the price rise from Z and Flick will be based on the wholesale rate they are now getting + margins, it may be too late to switch to another provider on contract as they too will be increasing there price based on there new wholesale rate right now for new customers.

I signed up to meridian in April on a 5 year term which was a big jump in price ($1.17 incl GST daily charge and 28.96c/unit price all incl GST and 17c solar buy back with $300 signup credit) from Genesis plan we were on prior on a 2 year contract when it ended (60c daily charge, 22.5c/unit price all incl GST and 12c solar buy back. I am glad we signed up to the 5 year term with Meridian in April as we can exit it after 2 years but Meridian will have to honour the price for 5 years if we wish to stay for full 5 years. I can only see the prices increase quite a bit now every few months or every April atleast.

Do whatever you want to do man.

Jase2985

13457 posts

Uber Geek

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Lifetime subscriber

#3272414 16-Aug-2024 12:01

prob:

FYI my electricity company, Z Energy, buys back surplus electricity a the going market rate. As this was recently 90c a kWh, this will dramatically improve the economics of having solar..

https://www.z.co.nz/products-and-services/z-app/power-your-home/wholesale-power-rate/

the problem is the times where power prices are generally high are also the times when you are not really generating much power from solar.

HarmLessSolutions

969 posts

Ultimate Geek

Subscriber

#3272466 16-Aug-2024 12:29

Jase2985:

prob:

FYI my electricity company, Z Energy, buys back surplus electricity a the going market rate. As this was recently 90c a kWh, this will dramatically improve the economics of having solar..

https://www.z.co.nz/products-and-services/z-app/power-your-home/wholesale-power-rate/

the problem is the times where power prices are generally high are also the times when you are not really generating much power from solar.

It does provide an opportunity to maximise gains by exporting from a battery to match peak rates.

Interesting to learn that Z is now accepting customers with generation. When did Z start buying domestic generation? When they first arrived on the scene they flatly refused to take us on assumedly because we had an export meter.

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

wellygary

8312 posts

Uber Geek

#3272593 16-Aug-2024 15:13

prob:

FYI my electricity company, Z Energy, buys back surplus electricity a the going market rate. As this was recently 90c a kWh, this will dramatically improve the economics of having solar..

https://www.z.co.nz/products-and-services/z-app/power-your-home/wholesale-power-rate/

But there is no way you would borrow money based on what the wholesale spot rate is/might be....

Sure it works for you now, but in August 2023 the spot price was well anchored around 15c/unit

LightbulbNeil

57 posts

Master Geek

#3272599 16-Aug-2024 15:55

billgates:

I signed up to meridian in April on a 5 year term which was a big jump in price ($1.17 incl GST daily charge and 28.96c/unit price all incl GST and 17c solar buy back with $300 signup credit) from Genesis plan we were on prior on a 2 year contract when it ended (60c daily charge, 22.5c/unit price all incl GST and 12c solar buy back. I am glad we signed up to the 5 year term with Meridian in April as we can exit it after 2 years but Meridian will have to honour the price for 5 years if we wish to stay for full 5 years. I can only see the prices increase quite a bit now every few months or every April atleast.

I also signed on to the 5 year plan in November last year. I managed to change from the standard user rate to the low user rate daily charges, as our imported amount of power is less than 21kWh a day average now. Peak winter is 30kWh a day including the spa pool. The low rate charges for me are 69c incl gst. Our buying back for electricity is 29.85c/kWh in Hamilton, and sell back at the flat rate of 17c no gst. At 30kWh/day it is slightly cheaper to have the higher daily charges $2.1237 daily charge (incl gst) and the lower supply charge of23.32c/kwh (incl gst). You can change the rates during the term of the contract, but I have decided not to push my luck in case they change their minds on that aspect of the contract.

We did look at the wholesale rate option for buying and selling solar and am happy that I did not do that. Meridian did tell me this year, that they will honour the low daily charge rate of 69c/day for the full term of the contract. So I am very happy with the outcome over all, as I don't need to do anything and get no power bills over the course of the year. The only thing we need to look out for is deciding what plan to choose next in Sept/Oct 2028. My wife and I have given up on programming the washing drying etc when the sun shines, and just run anything and everything when we get the time. Its good without needing to try and maximise the last dollar in the system. As it is, we are on track to have been fully paid off by 6 years 4 months at current power price rates and our consumption from the date of the system going live. This year in Hamilton the Pine pollen has been very early. So will need to get the soft brush and wash down the panels and try and keep ahead of the pollen on the panels already.

In 28 we will look again at battery options and see what is compatible with the Fronius 3phase inverter. It maybe that when the inverter gets to it's end of life that we get an inverter and compatible 3 phase battery system. Looking at the Fronius simulator , we will need a 22kWh battery to get us to being basically off grid during winter and having the supply charges paid for from the summer sell back to the grid.

dantheperson

174 posts

Master Geek

#3272603 16-Aug-2024 16:02

wellygary:

But there is no way you would borrow money based on what the wholesale spot rate is/might be....

Sure it works for you now, but in August 2023 the spot price was well anchored around 15c/unit

Was it really that high Aug 2023? Cause that's about what you get as a fixed rate from most retailers. So if you can get $1/kw with flick over the last few weeks, and still get 15c when the hydro lakes are flooding, that seems like there's only upside

Nice chart of spot prices on emi here
Aug 2023

May and June was more of a problem 0.01 cents/kWh

zenourn

271 posts

Ultimate Geek

Trusted

#3272606 16-Aug-2024 16:05

wellygary:

But there is no way you would borrow money based on what the wholesale spot rate is/might be....

Sure it works for you now, but in August 2023 the spot price was well anchored around 15c/unit

Yes, if we had a large rain event or two in the hydro areas prices would drop instantly. The higher prices should also encourage more investment.

Realistically though the current shortage may continue for a while as the snow storage is at extremely low levels which will impact on spring inflow into lakes (https://www.meridianenergy.co.nz/power-stations/snow-storage).

It also doesn't seem easy to get new generation in place. In my areas there are two projects both with problems. The first is a wind farm that is having issues getting the capital (https://www.mtcasswindfarm.co.nz/mt-cass-wind-farm-exploring-next-steps/) and the second is a large solar farm but locals don't want it (https://www.odt.co.nz/star-news/star-districts/star-north-canterbury/solar-farm-proposal-making-locals-blood-boil).

wellygary

8312 posts

Uber Geek

#3272607 16-Aug-2024 16:06

dantheperson:

wellygary:

But there is no way you would borrow money based on what the wholesale spot rate is/might be....

Sure it works for you now, but in August 2023 the spot price was well anchored around 15c/unit

Was it really that high Aug 2023? Cause that's about what you get as a fixed rate from most retailers. So if you can get $1/kw with flick over the last few weeks, and still get 15c when the hydro lakes are flooding, that seems like there's only upside

I was looking at a fairly quick coarse chart, so the day time low might have been hidden by the evening peak prices.,..

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