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pstar008

352 posts

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#238018 29-Jun-2018 06:06
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Hi I am considering install a Solar panel system, and got a few quotes:

 

Got a few questions, mainly due to the differences between the solutions they provided, and each one state that they provide the most suitable solution for me.

 

1. Hot water timer vs Power diverter?

 

Some suggested the diverter solution and the timer solution for hot water heating as a cheap alternative, but one odd one suggest timer solution over diverter as he said people complains that the diverter solution can cause the water not been heat sufficiently during winter. Not good if that is true! I am consider a system with roughly 4 kW panel output, unfortunately, it is not all facing north, will be spreed across east, north and west.

 


2. 3 kW inverter for a 3kW plus panel output?

 

As the panel as spread across multi directions, one quoted my a 3kW converter as it can handle up to 4.5 kW output which is exactly the maximum output I am looking at for a premium LG panel solution(320 watt per panel), so it should be fine I guess? But I think I am going to throw 5 kW inverter upgrade for future proof as I am consider install battery in few years, it is too expensive to make finical sense at the moment.

 


3. Panel optimizer or not?

 

When provide quote, some mentioned panel optimizer, and one don't think I will get best result without using it, at 100 bucks each, it will add about 1500 over the installation cost, how much difference it will make? I am going to look at the data sheet he provided, but real world difference?

 


4. Smart meter installation?

 

One does mentioned an optional smart meter installation so that I can see my power usage, otherwise without it, I can only see my solar output. Which is fine as some may not bother to tell that cost upfront, but a $1400 for a smart meter to see my power consumption ( he did mentioned that as my power switch board is full, that's why it's expensive, maybe?)? What's the difference between the one I got from my current power provider?

 


Not sure more research myself going to help much, so just throw my questions over the forum.

 

 


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rogercruse
381 posts

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  #2045827 29-Jun-2018 07:05
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Had Solar panels installed about 3 years ago and while I can't answer all your questions,  I can offer my opinion about power diverters & timers.

 

 

 

We initially used a timer and then replaced it with a power diverter. Also had a bigger hot water tank installed to store more heated water.

 

 

 

The power diverter works well and means that any unused power is allocated heating water instead of being sold to the power company (at 8c a unit is really 'selling' is it?). There's also a timer on our system so we can still heat water overnight (useful in the middle of winter when there isn't enough sunlight) plus an override option for an additional boost.

 

 

 

Also, The monitoring power provides a good insight into our power generation and consumption. Especially when we had a Tesla PowerWall installed. 

 

 

 

BTW  the Tesla PowerWall is version 1 system and was installed as part of a promotion from Vector. Whil not as clever as a version 2 system is adds enough power to provide lighting when there're power outages.


E3xtc
691 posts

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  #2045842 29-Jun-2018 07:53
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fwiw I have 4kw of panels and a 5kw inverter. I did this for future proofing as I was thinking I may want to throw another kw of panels in the future on the roof...have not yet (this was about 5 years ago) but still might. 

 

I did look into the diverter initially, but I am lazy and didn't want to go down the DIY way and the purchased/manufactured ones meant the ROI was extended to a point where it didn't really make sense once you factor all the costs involved and the payback. 

 

No idea on the optimizer. Don't have one, didn't know about them, so *shrug* :D

 

Re: Smart meter installation. While we have a smart meter, we don't get anything out of the smart meter. Any analysis is done via the bluetooth connectivity directly to the Inverter. So while its cool to get some figures and stuff, I just don't use it. While we are aware of using timers etc to make the most out of the solar generated, there is only so much one can do, so I don't spend my life crunching the numbers on something that we are already trying to make the most out of. 

 

Check out your power provider too re buy back rates. We were with Meridian for the most, but about a year or so ago switched to P2 Power; P2 give you an elevated buy back rate (16c) for the first 50kW in a fortnight then it steps back down to what others normally offer (8c). 

 

In the time since we installed the buy back rates have changed, so the "investment" as such isn't as sharp, and in that respect while it is a shame, I am not really that concerned about. Its on the roof, its paid for, and its helping offset our energy use, so I still see it as a positive. 

 

Good luck with your research/decision! :) 


 
 
 
 


pstar008

352 posts

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  #2045850 29-Jun-2018 08:17
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Thanks for share your experience, good to know someone used both.

 

Is there any particulate  reason for you to switch diverter from timer?

 

So for you case, not enough hot water is never an issue for you after switch to diverter?

 

rogercruse:

 

Had Solar panels installed about 3 years ago and while I can't answer all your questions,  I can offer my opinion about power diverters & timers.

 

 

 

We initially used a timer and then replaced it with a power diverter. Also had a bigger hot water tank installed to store more heated water.

 

 

 

The power diverter works well and means that any unused power is allocated heating water instead of being sold to the power company (at 8c a unit is really 'selling' is it?). There's also a timer on our system so we can still heat water overnight (useful in the middle of winter when there isn't enough sunlight) plus an override option for an additional boost.

 


rogercruse
381 posts

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  #2045856 29-Jun-2018 08:35
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pstar008: So for you case, not enough hot water is never an issue for you after switch to diverter?

 

 

 

Almost never an issue... When there's not enough sunlight for a couple of days then the timer / boost option make sure we have enough hot water.

 

Certainly, the bigger hot water cylinder was a wise move.... If  I were doing it again, I would get a system where the water temperature could be monitored / incorporated into a home automation system for the extra visibility and control.


pstar008

352 posts

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  #2045857 29-Jun-2018 08:35
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Thanks E3xtc.

 

So you don't have either timer or diverter? but I guess when the buy back rates was much higher, so the extra power generate during day time un-used isn't really a ripe off. I think my power provider Mercury is 8c as standard and can be 16c if I am willing to lock up contract for 3 years, which I hate. Which is why unless I install a battery like the lucky one @rogercruse, I want to install either timer or diverter. or I can switch to P2 power, if they are available to me in Auckland.

 

I think I will future proof for a 5kW inverter for extra $600.

 

Optimizer, don't know, sound like an up-sale from one quote provided as optional extra. But the other one insists it's best for my optimised output, and I guess the reality is either with optimizer installed or not, I will nervier see the theory/rated maximum output from my 14 panels as they are facing 2 or 3 different directions. I guess I will trying to get from them the likely different the optimizer will make.

 

Yes smart meter, I don't think I will install that, not for $1400 extra. Just kind of surprise none other three quote mentioned to me at all, or I totally forgot if been mentioned as extra, can you recall how much it cost you for smart meter, of course if it cost extra and not part of the installation package?

 

Yes, my intention is it has to make sense for ROI and hopefully maximum it, but put consideration of future proof, and some options may or may not help depends who you ask ...

 

E3xtc:

 

fwiw I have 4kw of panels and a 5kw inverter. I did this for future proofing as I was thinking I may want to throw another kw of panels in the future on the roof...have not yet (this was about 5 years ago) but still might. 

 

I did look into the diverter initially, but I am lazy and didn't want to go down the DIY way and the purchased/manufactured ones meant the ROI was extended to a point where it didn't really make sense once you factor all the costs involved and the payback. 

 

No idea on the optimizer. Don't have one, didn't know about them, so *shrug* :D

 

Re: Smart meter installation. While we have a smart meter, we don't get anything out of the smart meter. Any analysis is done via the bluetooth connectivity directly to the Inverter. So while its cool to get some figures and stuff, I just don't use it. While we are aware of using timers etc to make the most out of the solar generated, there is only so much one can do, so I don't spend my life crunching the numbers on something that we are already trying to make the most out of. 

 

Check out your power provider too re buy back rates. We were with Meridian for the most, but about a year or so ago switched to P2 Power; P2 give you an elevated buy back rate (16c) for the first 50kW in a fortnight then it steps back down to what others normally offer (8c). 

 

In the time since we installed the buy back rates have changed, so the "investment" as such isn't as sharp, and in that respect while it is a shame, I am not really that concerned about. Its on the roof, its paid for, and its helping offset our energy use, so I still see it as a positive. 

 

Good luck with your research/decision! :) 

 


pstar008

352 posts

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  #2045859 29-Jun-2018 08:40
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Yes, kind of surprise that there isn't a solution out there doing that already, which is the impression I got when getting quotes, is Tesla power wall 2 suppose to doing that in term of more control over hot water?

 

Hot water can be used as cheap battery, but will be better you can monitor/control temperature more.

 

rogercruse:

 

Certainly, the bigger hot water cylinder was a wise move.... If  I were doing it again, I would get a system where the water temperature could be monitored / incorporated into a home automation system for the extra visibility and control.

 


Aredwood
3885 posts

Uber Geek


  #2045860 29-Jun-2018 08:40

Definitely get the hot water diverter. As it also helps to increase the amount of self consumed power used by other appliances. The diverter should have a timer or bypass function. So if you cylinder didn't fully heat during the day. It can heat in the evening.

Be careful if you currently have separate meters for things like hot water. Or more than 1 phase. As by getting solar, you can loose the cheaper power for water heating. Otherwise you could be exporting power through meter 1, getting paid 8c / unit. And importing power at the same time through meter 2, getting billed 25c / unit. Same thing can happen with multi phase, depending on how the meter has been programmed.

Since you are considering batteries. Also consider a much larger hot water cylinder. Which also allows you to make better use of the diverter. As you connect the bottom element to the diverter. Set its thermostat to 80deg or the max temp that the cylinder supports. And use the top element for boosting. With its thermostat set to 60deg. The cost per KW/Hr of storage for a hot water cylinder is far cheaper than batteries.

What are panel optimizers? Since the inverters all support MPPT. Without seeing more information, the panel optimizers sound like snake oil.





 
 
 
 


timmmay
16529 posts

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  #2045864 29-Jun-2018 08:47
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I like the idea of solar, but I think it's still immature. That it shuts off during a power cut is annoying. The cost of batteries makes having storage prohibitive, unless you count hot water. Batteries to shift load and give you power during an outage is what would really make solar valuable. My reading suggests practical payback periods are decades, longer than most people stay in a house. Friend of mine got solar, they have two hot water cylinders and a spa pool, cost them about $15K. I think his payback period is well over a decade. He likes it but mostly as a toy.

 

What are your key drivers to get solar? Do you want to go off grid? Do you want to save money long term?


pstar008

352 posts

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  #2045866 29-Jun-2018 08:52
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Quite right about payback period is over a decade.

 

Aim to save money long term, initial because I have a couple of thousands saving laying around, but a solar system certainly cost way more than that :D

 

And it seems that panel technology is still in progress, LG have some panel 10% more efficient than the other panel i got quoted, and they seems have something 10% more efficient coming soon.

 

timmmay:

 

I like the idea of solar, but I think it's still immature. That it shuts off during a power cut is annoying. The cost of batteries makes having storage prohibitive, unless you count hot water. Batteries to shift load and give you power during an outage is what would really make solar valuable. My reading suggests practical payback periods are decades, longer than most people stay in a house. Friend of mine got solar, they have two hot water cylinders and a spa pool, cost them about $15K. I think his payback period is well over a decade. He likes it but mostly as a toy.

 

What are your key drivers to get solar? Do you want to go off grid? Do you want to save money long term?

 


pstar008

352 posts

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  #2045871 29-Jun-2018 09:04
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Does sound like a snake oil to me. But the idea behind it is it different than MPPT as it allow individual panel still maximum it's output in case any one in shade, which happens less frequently once I cut a couple of tree in my property, but still there are houses and higher trees outside may cause shade later afternoon, or partly cloudy I suppose.

 

I think that the optimizer model they quoted from one insist that I need them.

 

https://www.solaredge.com/products/power-optimizer#/ 

 

 
What are panel optimizers? Since the inverters all support MPPT. Without seeing more information, the panel optimizers sound like snake oil.


timmmay
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  #2045885 29-Jun-2018 09:12
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I dunno if you'll save money long term with solar. If you put the money in an investment fund and move to a power provider that suits you (I use Electric Kiwi for the hours of free power a day, which saves me 20%) you'll possibly come out better in 20 years. Going solar now is probably more about the intangible benefits.

 

Once you can power your house in a power cut or store power then the situation will be different.


Aredwood
3885 posts

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  #2045891 29-Jun-2018 09:29

Since you will have panels facing in 3 different directions. Does your chosen inverter have 3 separate MPPT inputs?





pstar008

352 posts

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  #2045955 29-Jun-2018 11:14
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Aredwood: Since you will have panels facing in 3 different directions. Does your chosen inverter have 3 separate MPPT inputs?

 

The other quote has to MPPT inputs as it was quoted for two side for 16 panels.

 

I think the point for panel optimizer is that it will have a finer scale of optimizer per panel that replace the need for MPPT. But I haven't look at the inverter data sheet yet, I would think 3 MPPT is probably good enough if the inverter support it already, is that what you meant?


pstar008

352 posts

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  #2045956 29-Jun-2018 11:18
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That's where I got interested in solar solution, but cost not justify it yet. I've been hopping different power company for last few years, got to the point that hopping doesn't make sense (doesn't really make difference in term of saving as my usage it typical most usage is night and weekend. But still worth looking at power companies from time to time ans consider change my power usage instead. As solar require that as well, unless I have a battery.

 

timmmay:

 

Once you can power your house in a power cut or store power then the situation will be different.

 


xontech
259 posts

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  #2046026 29-Jun-2018 13:30
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What power diverters do people recommend? And their cost too please. Obviously need to factor in electrician installation costs too.......


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