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I've seen estimates of an extra 20c per watt installed here - so AUD$8k for a 40kW system with no tracking.
But that assumes a certain size of array.
On a roof they're just battening on a couple of aluminium rails and dropping cable into the house, by contrast
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@NTA and then seeing how much work is needed to get the optimal pitch? But I guess the railing system would have scope for that to a certain extent. With the current situation we are keen to really look at solar etc, but we also desperately need to extend up and/or out. So we've kept putting it off.
Keen to hear how things progress @Snowy.
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@Paekakboyz pitch can be important - my roof for example is optimal for October/November which is great as it isn't too hot and there tends to be a lot of sun. My roof is probably around 30 degrees pitch where a lot of modern builds are 23ish.
NOTE: adjusting the pitch on the roof by adding extra framing = extra cost. If your roof isn't flat, generally go with what is there. If you're going to extend, then I'd suggest getting good passive design done at the same time including the right pitch on a north-facing roof.
Ground mounts without tracking have to determine their pitch at time of install. I've seen two general options in either single-post and rail frame like this, which looks to be about 3.0kW-3.6kW depending on panel size:
To the ground-frame ones which are an option if you have more space - the one in the picture is quoted at 28kW which would run about 4 households at peak:
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@NTA said in Solar Power and Storage - a nerd's view:
@Snowy said in Solar Power and Storage - a nerd's view:
@NTA Is ground mounting really more expensive than roof?
Typically, yes. First you probably need a geotech survey depending on local authorities. Posts and frames have to be standalone structural (maybe concrete footings etc), wind factor is different, channeling for power cable and then of course the extra cable itself. All adds up.
Of course in some cases it makes absolute sense depending on all the factors involved.
Yeah, we fit into the last sentence. None of that scares me too much, given that I have a geotech report in front of me and the engineer doing the foundations for the house will be able to design it. The guys doing the foundations will be putting in poles, so a few extras won't be too difficult. We have to get a trench dug to get cabling to the house so a few extra meters won't matter there either. Basically, we have everything to do what you describe happening anyway.
Pitch is an easy one - should be approx the same as lattitude for obvious reasons. SYD is about 33deg sth so you are nearly bang on Nick.
We are 36deg sth, so I guess the question is - typical 1930 bungalow in NZ has 15 - 25deg roof (I don't actually know what ours is yet) how much extra efficiency do I get from the optimal pitch with the extra 11 to 21deg? That seems significant to me.
If I do a ground array, do I do tracking or fixed? Two axis tracking or one?
Have to find some numbers on the efficiency gains somewhere I guess. I can probably save a bit by having fewer panels if it is optimised too, and I will be able to clean them easily on the ground.
How many KW is your system Nick? Is it enough?
I will probably go powerwall or some battery too. Had the panasonic in last house and it was good. They manufacture them for Tesla anyway I believe.
Going to need a heap out of the panels because going to buy my Dad's Audi etron too. He wants a smaller electric car so I'll buy his.
@Paekakboyz Spacecraft do indeed have solar panels for running the ship, as well as solar electric propulsion. So yes, with a little (well a lot really) more advanced tech, that is quite possible.
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@Snowy said in Solar Power and Storage - a nerd's view:
How many KW is your system Nick? Is it enough?
6.5kW of panels with a 5kW inverter - Powerwall version 1 coming up to its 5th birthday. I would consider it enough for about 75% of days, yes. Still useful to have the grid of course for rainy weeks and occasional heatwave days where the AC (an inefficient pig of a piece of shit) runs in a house with very few passive design features.
Note: make everything as energy efficient as possible (AC/heating) and you could get away with 5kW for the house. Is it just the 2 of you? If you add the eTron you're probably best off going for whatever the local authorities allow (e.g. there are 10kW limits in some parts of Australia for grid-connected systems).
Many options out there for batteries these days.
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@NTA That is what I put in at the last house. We don't get as much sun as you though and it wasn't quite enough. Also had to split the panels onto east and west facing aspects so wasn't ideal.
Yep, will still be grid connected. Yep, just two of us, but electric car, hot tub, might heat the pool a bit (probably use an evacuated tube solar hot water system for that as I have one already , so another story).
Didn't know about restrictions on output, don't think that we have that here. Will look into it, thanks.
Onto the energy efficiency. Did an eco design course a few years ago. House already has LED lighting throughout. Have organised injected wall insulation, blanket under floor, might even go up to R7 for the ceiling. New double glazed joinery throughout . Having a woodburning Rayburn or Aga with a wetback that will run radiators (suits the old house), it also has a heat pump / aircon and a ventilation system. We should have temps / humidity sorted I think.
Who else is doing batteries?
I have considered off grid, but I think we would still need to go lead acid if we did that and then I would need a generator, so went off the idea.
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@Snowy said in Solar Power and Storage - a nerd's view:
Who else is doing batteries?
So in this part of the world for lithium you have known brands like Tesla, LGChem, sonnenBatterie, Enphase, and I think Fronius do a hybrid unit. After that there is a whole heap of Chinese manufacturers entering the market.
Lead acid is always there, but the fact it is a well-known technology doesn't mean it is bulletproof. Control systems are the problem and it isn't actually a very common technology compared to Lithium, which is becoming plug n play at a rapid rate of knots.
e.g. My PW1 took the techie a few hours to wire in correctly, because the inverter hooked up to a Battery Management System which hooked up to the PW1 itself. Now they're coming as all-in-ones with an inbuilt inverter (Tesla PW2) or compatible plug tech for a wider range of inverters. Less piss-farting around.
There are also a couple of quirky options like Redflow (poorly named IMHO) ZCell - using a Zinc-Bromine (ZnBr) fluid solution for very stable operation. The issues are:
- 80% round trip efficiency (put in 10kWh, get 8kWh out) compared to lithium which is 90-94% depending on manufacturer.
- Cost per kWh - not much volume in the market keeps prices relatively high
https://redflow.com/products/redflow-zcell/
However I know that these ZnBr units are being used by telcos in NZ as part of the power setup for things like 4G towers - even in the Alps! Some of the mobile phone infrastructure has solar as the primary source with one of these ZCells in a shed next to it (they also have a diesel gen in there but usage is < 2% of the time I think).
I have considered off grid, but I think we would still need to go lead acid if we did that and then I would need a generator, so went off the idea.
The issue with off-grid is the entry cost - you need to account for about 4 days without sun, and not your most frugal estimate either; average usage + 50% for emergencies IMHO. Probably starting at NZD$50K ish.
If you had a "lifestyle block" and needed to pay the power company $150K to string in some power, it becomes well worth it.
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@NTA said in Solar Power and Storage - a nerd's view:
The issue with off-grid is the entry cost - you need to account for about 4 days without sun, and not your most frugal estimate either; average usage + 50% for emergencies IMHO. Probably starting at NZD$50K ish.
That's why I went of the idea - not the cost - the days without sun. If we get a Nor easter we can end up in cloud. Elevated section that looks out sea so it can blow straight into our place and not having grid backup could be a problem (hence the generator comment).
Thanks for the info on batteries will look into those.
We do have a "life sentence" block but I have grid power. Three phase to my new barn which is about 300 hundred meters from the house site. I did meet some people the other day who are off grid and you have exactly described their situation, 150k to get the power in, or 50k for off grid batteries, generator, etc. They actually really like it though.
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O.K. so I have more info. I only have one section of roof that is north facing and 12 to 15 deg pitch, so can put some panels on there with appropriate fittings for angle. My architect / structural engineer (very useful dual skills in one guy) has a good solution to get some more on the house. They can be mounted off the poles that are holding up a huge north facing deck and we can get our 36 deg on those as well. Below eye line out of sight and IIRC they are usually about a mtr wide so I can get 25 panels going easily.
I think I'm going to go with about 10kw. We will end up with two electric cars so going to need it.
Next questions, recommendations on panels? It's been a while since I did much research on this. My last ones were LG, good quality but was before micro inverters were around (just). If I understand it correctly microinverters mean that you still get power from the full array even if one panel is shaded?
So microinverters?
Brand of panels?
Size of panels? I assume just go high 400+, so that I don't need so many? How many panels have you got for 6.5kw @nta ? I'm thinking 25 for us to get my 10kw.
Assume monocrystalline is best?Any ideas / tips welcome.
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@Snowy you can either go the full microinverter route, or the halfway point which is power optimisers. Depends on the brand of panel and/or inverter you get.
https://www.solarquotes.com.au/blog/microinverters-vs-dc-optimisers-which-option-is-best/
You're right in that microinverter/power optimisers mean that each panel's voltage is independently tuned regardless of partial shading etc. You effectively have one "string" per panel balancing voltage and therefore output.
If you have everything facing the same direction with no likely partial shade situations, you may not even need them.
Besides that, for your situation, given cash is no object, a Tier 1 panel like LG would be good, and something in the 350kW+ range. Most installers will have packages in sizes 4-10kW they can give you, and best to ask for a couple of quotes with a couple of installers IMHO.
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@Tim massive, massive infrastructure build. Only China could do this. USA maybe if they pulled finger.
This sort of tech could assist Australia get where it needs to be with renewables across state lines, but the cost is prohibitive.
Better to go "standard" HVDC to get the wind and solar farms connected.
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Yeah, surely local micro generation is a better solution. There may be some population "control" issues in China as well.
These look good:
*"The International Energy Agency says solar electricity is now being made more cheaply than any other method of production. But solar panels currently only convert around a fifth of the sun's energy that falls on them into electricity.
Sunlight is made up of the spectrum you see in a rainbow and silicon, found in nearly all solar panels, is best at converting the red part into electricity.
But UK-based company Oxford PV is combining silicon with a material called perovskite - a semi conductor mineral with a crystal structure of titanium calcium oxide - which turns the blue wavelengths into electrical energy. This chemical sandwich can increase the panels efficiency to 30-40%.
They are going into production this year and expect early applications to be on rooftops where customers want to maximise the wattage from a confined area."*
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@Snowy all comes down to cost - solar panels that were 11% efficient were the norm for domestic applications ten years ago.
Mine are 5 years old and were about 18% efficient at install (they degrade about 1% of existing yield per annum so would now be getting down to 17%)
Most of the Tier 1 panels were 20-22% at the time, and always getting better. That's why the wattage increases without panel size increasing - efficiency.
Mine are 250W but 350W+ is fairly normal now.
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@NTA Mine were 250w as well. From memory they had a 20 year warranty to operate at 80% plus (of original output) which actually sounds a bit low. Pretty hard to measure that in a home system though on any given day with the sunlight variable.
No idea what the Oxford ones will cost but if you are reducing the number of panels by that much could be economic. Say a third more efficiency on top.
These look interesting too:
https://www.pv-magazine.com/2020/05/06/a-new-passive-technique-for-cooling-solar-panels/https://www.sciencedirect.com/science/article/pii/S2090447913000403
The tech keeps changing so you have to take the plunge at some point I guess.
The other issue is supply with Covid and ships not being unloaded in NZ. Hopefully that will be fixed before I want them and isn't a problem as yet. -
I decided to reply here as it seemed like a better place for it. Also: the Powerwall is celebrating its 5th birthday today, so yay me.
@pakman said in Electric Vehicles:
https://wattsupwiththat.com/2021/01/27/bright-green-impossibilities/
"I sincerely hope that everyone can see that any of those alternatives are not just impossible. They are pie-in-the-sky, flying unicorns, bull-goose looney impossible."Interesting language. A lot of angry comments under that article as well
Beyond the fact that WUWT is a known climate science denial/doomscare blog, and Eschenbach is not considered scientifically literate by any reasonable measure, I want to hone in on a couple of points he uses:
The NREL document he's quoting for solar at "8.3 watts per square metre" is from 2013
Significant improvements have been made since then , with cell efficiency doubling, so maybe quote that figure above 17 watts/sqm or more - due to better inverter tech. Ignoring deployments that use tracking tech to extract even more than the stated efficiency.Wind turbines quoted at 2MW is on the small side. Land-based turbines are typically 3MW or above for grid scale installations. Twice that or more for offshore turbines - average turbine size in Europe installed in 2019 was 7.8MW. I'd be happy to say that average installed wind turbine capacity for 2021 onward is 4MW and leave it at that.
(Unfortunately both of these are examples of the denier scepticism: use old or current figures like they're never going to get better).
We've just improved both technologies by 100%, and therefore halved any figures used in the article for time, land use, or labour. Nice. That's without even adding any firming storage or pumped hydro to support the capacity factor of wind/solar.
Nuclear is not financially viable in any of these scenarios, however I think there will continue to be development here to help with the last 25% of need on the grid. Governments will probably end up carrying the can for that.
I'm in no way belittling the challenge. Net zero is a freaking huge effort and the inaction to date hasn't helped kick it along except in certain cases e.g. R&D under certain schemes. We'll basically have to pivot all mining of fossil fuels into mining of other things to keep the movement going, as one example, and electrifying heavy industry will be tough.
On the plus side for the article: looking at the problem in terms of all FF burned is really key. A lot of studies just concentrate on the electricity grids and manufacturing, and forget the billions of cars running around - particularly here in Oz where we have no emissions standards.
At the same time, we need to consider the transformative nature of something like an EV: A petrol engine might convert about 20% of the power in liquid fuels to energy at the road (losing a lot to heat), while electric cars are close to 80% on the same measure. Already you're achieving a massive difference with each FF car taken off the road, even considering the manufacturing differences for the battery - which again will get more efficient over time.
An overarching point is the efficiencies in supply chain: if your car runs on wind/solar, you're not shipping or refining petrol, and so you're not burning crude to ship petrol. It is a force multiplier effect. Then you have the downside of replacing solar/wind every 20-30 years, which produces the upside of getting more efficient tech replacing old tech more rapidly than a 50-year coal or nuclear plant, but what about the waste? We'll make new recycling industries to ensure we keep a closed loop on things? Who is paying for that?
Here come the Unintended Consequences
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@NTA said in Solar Power and Storage - a nerd's view:
Here come the Unintended Consequences
The consequences are obvious - we're going to pay more for electricity. And the more we pay for wind and solar the less we're going to decarbonise our grid per dollar spent compared to alternatives.
Solar Power and Storage - a nerd's view