Solar Panels

lovestotravel said:
My plumber is trying to get me to install a heat pump hot water system, I'm sceptical of the lower pressure and lower water temps and slower heating it will provide.

Anyone have experiences with these ?

Currently have a 15 year old 390L gas storage tank hot water which we love but it's about to die :(
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Think of this as a airconditioner that only heats.

It takes the difference in temperature from the ambient air (located outside under cover ideally) and a temperature at negative some degrees celsius. Depending on where you are and the brand/model you choose then generally you generate the same heat as a straight electric HWS for 1/3rd to 1/6th the electricity used.

I've been wondering about HP HWS and whether they produce 'waste' cold airconditioned air? If so then it might be worthwhile having a diverter into your house for part of the year. Similarly, I wonder if you could improve the performance of the HP HWS by directing the hot air from an existing external aircon system towards the inlet duct of the HP HWS?

For some reason, the cost of heat pump hot water is the flip side of solar panels vs the USA. Perhaps two to three times the price of in the US.

A good HP HWS can pay for itself (the cost difference) in as little as 8 months in Hawaii for example. Meanwhile PV installation is around 16x more expensive. A good chunk of the additional PV cost is from State Govt/County filing fees.
 
RAM said:
I've been wondering about HP HWS and whether they produce 'waste' cold airconditioned air?
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Yes it can
However the amount of “cold” is minimal and likely will not be worth the marginal cost of the additional ducting

Aircon producing hot air ducted to the heat pump HWS similar - it assumes that both will be “pumping” at the same time.

However commercial units exist which use waste heat to produce hot water etc. look up electricity tri-generation -using waste heat from electricity generation to for hot water, space heating and cooling.
 
Lithium I(r)on? You have to listen carefully!

Got a flyer in the mail promoting adding batteries to existing solar panels. Batteries are LiFe not Li ion. I've no idea of what is normal for household solar (or ev) storage.
 
Brissy1 said:
what is normal for household solar (or ev) storage.
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Lithium ion batteries come in many forms

Basically the chemistry is:
Anode : lithium-carbon
Cathode: lithium metal-oxide

At the Anode Lithium is oxidised which releases an electron

At the cathode Lithium is reduced into molecular form by capturing an electron.

Hence there is electron flow (electricity)

The metal can be Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Zinc (Zn), copper (Cu). From left to right they are one additional atomic number on the periodic table

Each has slightly different characteristics including stability over time, power density

Li-Fe has lower power density but is able to withstand charging to 100% compared to the others.
Li-Co and Li-Ni has better power delivery and density

Tesla batteries used to be Li-Co but there are serious environmental and social concerns re Co - see cobalt mining in the Congo (which the environmental zealots and celebrities tend to overlook). Tesla is using Li-Fe for a lot of their Model 3 and reducing the amount of Co and replacing it with Ni for their other batteries.
 
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Quickstatus said:
Lithium ion batteries come in many forms

Basically the chemistry is:
Anode : lithium-carbon
Cathode: lithium metal-oxide

At the Anode Lithium is oxidised which releases an electron

At the cathode Lithium is reduced into molecular form by capturing an electron.

Hence there is electron flow (electricity)

The metal can be Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Zinc (Zn), copper (Cu). From left to right they are one additional atomic number on the periodic table

Each has slightly different characteristics including stability over time, power density

Li-Fe has lower power density but is able to withstand charging to 100% compared to the others.
Li-Co and Li-Ni has better power delivery and density

Tesla batteries used to be Li-Co but there are serious environmental and social concerns re Co - see cobalt mining in the Congo (which the environmental zealots and celebrities tend to overlook). Tesla is using Li-Fe for a lot of their Model 3 and reducing the amount of Co and replacing it with Ni for their other batteries.
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From my school chemistry (50 years ago), I presumed "Lithium ion" batteries used an ion of lithium as the major component.
But is "lithium ion" used as a generic description of any lithium battery like the types you describe above? Eg the lithium ion motorcycle batteries I'm also looking at could be any you describe?
 
Brissy1 said:
But is "lithium ion" used as a generic description of any lithium battery
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Yes
The ion here is always going to be Li+
In the Lithium Cobalt batteries (lots of early Teslas)
At the Anode the oxidation half reaction during discharge:
LiC6 = C6 + Li(+) + e(-)
At the cathode the reduction half reaction during discharge:
CoO2 + Li(+) + e(-) = LiCoO2

During charging the opposite occurs

'Lithium ion" means anything from LiMn, LiFe, LiCo, LiNi, LiZn, LiCu or combinations such as LiCoNi, LiMnCu

Trivia
In the Energiser/Duracell batteries (alkaline batteries) it is the OH(-) which is oxidised with the Zinc anode: Zn + OH(-) = ZnO + H2O + e(-)
The ion here is the OH(-) which is supplied by KOH (Potasssium hydroxide) which is alkaline
Hence the name alkaline battery

Similarly the Ni-Cd rechargeable AA batteries uses Cd at the anode instead of Zn and Ni at the cathode. But KOH provides the ion
 
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Quickstatus said:
Yes
The ion here is always going to be Li+
In the Lithium Cobalt batteries (lots of early Teslas)
At the Anode the oxidation half reaction during discharge:
LiC6 = C6 + Li(+) + e(-)
At the cathode the reduction half reaction during discharge:
CoO2 + Li(+) + e(-) = LiCoO2

During charging the opposite occurs

'Lithium ion" means anything from LiMn, LiFe, LiCo, LiNi, LiZn, LiCu or combinations such as LiCoNi, LiMnCu

Trivia
In the Energiser/Duracell batteries (alkaline batteries) it is the OH(-) which is oxidised with the Zinc anode: Zn + OH(-) = ZnO + H2O + e(-)
The ion here is the OH(-) which is supplied by KOH (Potasssium hydroxide) which is alkaline
Hence the name alkaline battery

Similarly the Ni-Cd rechargeable AA batteries uses Cd at the anode instead of Zn and Ni at the cathode. But KOH provides the ion
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Thanks. Hopefully continuing research will get us improving efficiency. And ESG... I didn't know that about cobalt mining in the Congo, very sad.
My takeout from this... when comparing quotes make sure you're comparing apples with apples because all Li batteries aren't made the same.
 
Quickstatus said:
Trivia
In the Energiser/Duracell batteries (alkaline batteries) it is the OH(-) which is oxidised with the Zinc anode: Zn + OH(-) = ZnO + H2O + e(-)
The ion here is the OH(-) which is supplied by KOH (Potasssium hydroxide) which is alkaline
Hence the name alkaline battery

Similarly the Ni-Cd rechargeable AA batteries uses Cd at the anode instead of Zn and Ni at the cathode. But KOH provides the ion
Click to expand...
I use a lot of NiMH batteries. Mostly Fujitsu HR-3UTC and Ansmann Max e-Pro (which are the Fujitsu's in Ansmann wraps but no longer sold). These are rated for "up to" 2000 charge/discharge cycles, which if applying one cycle per day would be about 5.5 years. Theses are the best of their type available on the market and AA size NiMH batteries. And I only (*) charge them with Ansmann Energy 16 Plus or Ansmann Smart Comfort (the new model) chargers, and go through less than 100 charge cycles per year. I test the capacity of each cell once a year using an Ansmann Powerline 4 Pro charger (* the only exception to chargers mentioned earlier as this one measures and reports the actual charge capacity of the battery).

So based purely on manufacturer's rating of "up to" 2000 charge cycles and my usage pattern, these should be good for around 20 years of my usage pattern. I set my expectations that they will last me around 6-8 years. So far my early acquired Ansmann Max e-Pros are still holding 2000-2100mAH after about 7 years, which is pretty much as when they were new (manufacturer rates them for "Min 1900mAH").

Obviously different battery technologies have different characteristics. These quality NiMH cells are very stable, low self-discharge and in my usage pattern perform extremely well. But with an expected life of 2000 charge cycles, this technology is never going to be suitable for things like solar batteries and EVs, which need a life expectancy of more than 10 years to be viable.

Do you know how the different Li-ion technologies mentioned previously perform in terms of number of charge/discharge cycles? And is this impacted by the depth of the discharge and by the charging rate (slow verses rapid charging)?

The chargers I use with my NiMH batteries perform battery tests and apply the appropriate charge process, including "refresh" if needed. Do Li-ion batteries need this "refresh" process regularly and how does that affect the charging process for Solar and EV usage and the life expectancy of the batteries in Solar and EV usage conditions?
 
kookaburra75 said:
We took the plunge back in June to have solar panels fitted to Chez Kookaburra in Canberra. The ACT Government were promoting a scheme where there was a $7500 rebate and an nterest free loan through Brighte capital to pay off the cost. The sales person who dropped around was one of their electrical engineers, and happy to answer my questions about the brand of panels, the inverter and wiring - which I picked up through the information in the posts in this thread.

We have 8kW of Hyundai panels (with a efficiency and a lifetime warranty) and Sungrow invereter. Since it was switched on at the start of July it has just worked without any problems. It's currently a sunny Saturday morning and it's pushing out 6.7kW, and we're only using 1.3kW of that. Overall we're going to be ahead on costs. The loan repayments are half our old electricity bills, and when I retire in a few years we'll pay out the loan. As long as our overall bill (loan + elec useage) is less than our current bills I'm happy, as in a few years when I retire our bills will drop to virtually zero, and we've added to the capital value of our property.
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Just started to look at the stats of our system. Since we turned it on at the start of July, the numbers are pretty much what we expected.
solar_stats.png
Once we got over winter (which went on way longer this year), as we run electric panel heaters, the amount we are buying is dropping right off, and of course, the panels are generating more. We don't have air conditioning so over Summer I expect the amount we purchase to drop right off. In the past week on average/day, the panels have produced 39kWh , and we've purchased 2.6 kWh.
 
kookaburra75 said:
Just started to look at the stats of our system. Since we turned it on at the start of July, the numbers are pretty much what we expected.
View attachment 306931
Once we got over winter (which went on way longer this year), as we run electric panel heaters, the amount we are buying is dropping right off, and of course, the panels are generating more. We don't have air conditioning so over Summer I expect the amount we purchase to drop right off. In the past week on average/day, the panels have produced 39kWh , and we've purchased 2.6 kWh.
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Very similar to ours.
 
NM said:
NiMH batteries
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Batteries are just permutations of much the same stuff

The only difference between NiCd and NiMH is the anode is not Cd but M - meaning combinations in various proportions of other rare earths metals including Co, Mn and others. (Can’t remember). KOH still provide the ion. So basically a version of an “Alkaline battery”
No idea about real world performance because manufacturers tend to tout best case scenarios - the “up to” muddies the analysis.
 
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Other interesting battery technologies:

Zinc-Air . Actually Zinc-oxygen (drawn from the atmosphere). Cheap cheap but effective

Another is the Vanadium Redox. In this case Vanadium and sulphuric acid. Already deployed in various places.
Also cheap cheap
You can also see why it’s called Vanadium Redox and not Vanadium Sulphuric acid. Calling a battery “redox” is akin to saying “the sun rises in the east”. All batteries are redox chemistries. While sulphuric acid sounds toxic
 
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I'm hoping someone can clarify some conflicting info about inverters.
We have a flat, irregularly shaped roof with parapet walls and several large skylights and AirCon and gas heater units which limit us to 21 panels in 3 strings on tilt frames. It is intended that we will have some panels facing NE, some facing NW and some facing W.

My problem is that the various installers we have contacted have a variety of conflicting opinions as to what components are, or aren't, suitable.
We thought microinverters were an obvious choice but now we're not sure. Two installers tell me that we will actually need to have microinverters to cope with the panel strings facing in different directions. One of them seemed intent on leading us down the most expensive path for all the components.

The other 2 people we consulted suggested that, while they are happy to install microinverters if we want, their benefits were often over-stated. They say they are not only more expensive to install but also more prone to problems and more expensive to repair if they fail. They say that newer types of string inverters have overcome some shortcomings of previous ones and are more reliable and cheaper to repair or replace if problems occur compared to microinverters. I have been told that 3 MPP Trackers of a string inverter can each handle one string of panels so there is no chance of the whole system going down in the event of a problem with one string. Another comment was that panels are ultra reliable and failures are so rare nowadays that the ability to isolate a single faulty panel via a microinverter is over-rated and doesn't justify the extra cost. In the unlikely event of a panel failing they say the ability to isolate a problem to one string of panels is enough.

Comments appreciated
 
Quickstatus said:
AusGrid is changing the pricing for Grid access re solar exports

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Well that's a superb amount of manure polished so much that it shines!

Our panels are near perfectly sited for both aspect and angle here in Sydney, to the point that QCells' local reps were surprised by how much we generated per kW installed.

I can only speak of my experience for solar generation BUT the generation/export curve looks nothing like the nice little normal curve that has been generated for the 'greenwashing' campaign here.

The morning ramp up happens in a little over an hour (typically throughout the year), with it reaching around 85% of peak generation for that day's conditions. The ramp down is far more elongated but ends way before 8 to 9pm. It lasts roughly 4x as long as the ramp takes from 0% to 85% peak generation for the day.

We have no over-shadowing, nothing to get in the way of true theoretical generation.

Having asked for, and received several times, our detailed billing data from our various electricity providers provides the same graphical outcome.

What is the experience for others (especially for those with the auto monitoring that we missed out on in 2013)?


Is your typical daily generation profile a nice looking normal curve with equal length ramping and decline periods?
 

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