Panel Orientation?

I mean, is the utility controling your export factor based on their needs and forcing you to use a battery to consume power you stored earlier or 3 days ago? Or did they really bungle all the settings?

It makes a difference, because before we say someone is mistaken, we really need to know first what is intended. And it makes huge difference because the meaning of words can drastically alter the actual result.

Like a battery..... "its a two stage charger" there is a logical deficit if i take that on its face.

Graham Chiu wrote:

frank li wrote:Unless you were talking to the battery tech and he said the number represents the same thing as "absorbtion charge". Again thats why i said its a funky manual, the entire rest of the battery industry is on the same page with absorb and float settings. Most any charger will use bulk to get there.

When i have time ill look at the inverter manual deeper. Because i like the little knob in the website allowing you to turn self consumption up and down, which if you are dumping into the grid to save money, should be all the way down to like, off and batteries on standby float until grid out. Otherwise its going to be a very expensive exercise!

Ok, not understanding here.  Does the solax website have a knob on page to show the effect of self consumption vs export?

Usually here we are charged 29c/kWh, and receive 8c/kWh for that we export.  So, to save money we are told to self consume as much of the generated power as we can and any generation saved to the batteries we need to self consume when the PV generation is nil

I type slooooooow, my tablet is open to write and posts just pouring over like a flood in time of response.....

Ok so thats the schtick, economic return on self condumption because your agreement with the utility is taxing the sun and wants more than the advantage than they already get by allowing interties. Toads!

Now, in order to get max benifit the orientation, like an offgrid system, will need to be based on seasons and time of day demand and have a meaningful enough battery to take advantage of the array output resulting.

Thats all i was getting at.

And yes the website page for your inverter has a knob graphic to represent turning it up and dialing in self consumption.

frank li wrote:
I know the term off grid is strong and mesmerizing, but i totally get that you are not trying to be or operate off grid.

That is very similar to what your system was doing though. I mean, why are we even talking about batteries being flat after the electric water heater runs if it is not in fact operating with grid assist like a generator in an off grid?

So i am still missing something.

So, when the system is topping up the hot water, it should not be drawing all of the 3kW from the battery?  Is this something that I can change or should change?

Graham Chiu wrote:

frank li wrote:
I know the term off grid is strong and mesmerizing, but i totally get that you are not trying to be or operate off grid.

That is very similar to what your system was doing though. I mean, why are we even talking about batteries being flat after the electric water heater runs if it is not in fact operating with grid assist like a generator in an off grid?

So i am still missing something.

So, when the system is topping up the hot water, it should not be drawing all of the 3kW from the battery?  Is this something that I can change or should change?

No, mahaps not. Ifits money younare after then you need an accountant to depreciate the battery replacement cost or however they would term that and figure out how many cycles it is worth at the 29 and 8 cents.

If anything, if your electric heater or any other appliance or load will destroy the battery or excellerate wear beyond the beancounters number, it gets put on a utility load panel outside the reach of the inverted battery power seasonally permanently or in an automatic fashion. Of it outstrips battery costs over whatever payback scheme.....

This is why i only subcontract gridties for filler work.... im not an accountant, im a power system installer who designs for efficiency, reliability and max capability or bang for the buck and not payback and cost avidance schemes.

The utilities accountants are better than yours, everybody will get tired of replacing batteriies or now that grid tie pv is beyond parity with utility power in cost without solar, they are quite surely discouraging folks from doing the right thing by making it artificially more expensive to use.

So, it does really sound like that I should have got a tankless gas hot water system after the solar hot water.

What I was trying to do was top up the hot water with PV but the PV points NE and the hot water points NW. So, I don't know until the peak PV generation has finished whether or not I need to top up the NW hot water

frank li wrote:And yes the website page for your inverter has a knob graphic to represent turning it up and dialing in self consumption.

I"m just not seeing this.  I've poured over the website page and don't see any knobs at all

Graham Chiu wrote:So, it does really sound like that I should have got a tankless gas hot water system after the solar hot water.

What I was trying to do was top up the hot water with PV but the PV points NE and the hot water points NW. So, I don't know until the peak PV generation has finished whether or not I need to top up the NW hot water

Best i can suggest unless you are satisfied with your current level of offset. That or a air source heat pump, possibly. Cost would be higher up front and depending on outdoor temps, would likely still need a backup fuel heater.

If you use air conditioning the machine will also heat, dehumidify and move heat from the house and into the dhw system when dhw can recieve it, increasing efficiency of cooling space and heating water at the same time at 4 or so times the leverage of a resistance water heater watt for watt (or kWh).

If you are ok with gas, the tankless and turning off the electric will make the bean counters smile and maybe smile even more with a heat pump option in addition.

There are appliances for traditional central ac units which do much of the same stuff (divert waste heat to dhw) likely at somewhat lower efficiencies but way less cash if your ac is new or a good performer.

Graham Chiu wrote:

frank li wrote:And yes the website page for your inverter has a knob graphic to represent turning it up and dialing in self consumption.

I"m just not seeing this.  I've poured over the website page and don't see any knobs at all

!

Oh, that's not a website I've been to before.  I'll have to find time to see what's there.

Well, it's 7pm now, and my battery voltage peaked at 56.07V having never passed 55.4V before on the Lithium settings.
It's now down to 50.78V.
Is there an easy way to caculate the depth of discharge?  

Graham Chiu wrote:Well, it's 7pm now, and my battery voltage peaked at 56.07V having never passed 55.4V before on the Lithium settings.
It's now down to 50.78V.
Is there an easy way to caculate the depth of discharge?  

Not really, unless you let it sit static, no charge, no discharge. 1 hour minimum, arguably quite a bit longer. If the load is low and constant(ish) it will work to refer to a state of charge chart, i find within a few percent good enough for a system that is familliar to a person who lives with it.

I would use the systems soc meter if it has one. It should, it seems to have everything else.

This is the chart i use for a quick reference. All batteries are not the same, so technically you should extrapolate it from the narada battery manual charts on the subject. I like it because its Rasta!

Still, as long as it gets full (indicated in the manual and for various rates and types of use) it will be close to refer to a chart lime this once it is compared to narada for avoiding pitfalls.

I think its time to consult another install company. You are going to need a friend down there someone who can drop in and do an inspection, go over whhat you paid and possibly testify in court.

Online advice is problematic and i like manuals and conversations with the engineers or someone i know has it together more than myself. This equipment is expensive!

frank li wrote:

Graham Chiu wrote:Well, it's 7pm now, and my battery voltage peaked at 56.07V having never passed 55.4V before on the Lithium settings.
It's now down to 50.78V.
Is there an easy way to caculate the depth of discharge?  

Not really, unless you let it sit static, no charge, no discharge. 1 hour minimum, arguably quite a bit longer. If the load is low and constant(ish) it will work to refer to a state of charge chart, i find within a few percent good enough for a system that is familliar to a person who lives with it.

I would use the systems soc meter if it has one. It should, it seems to have everything else.

This is the chart i use for a quick reference. All batteries are not the same, so technically you should extrapolate it from the narada battery manual charts on the subject. I like it because its Rasta!

Still, as long as it gets full (indicated in the manual and for various rates and types of use) it will be close to refer to a chart lime this once it is compared to narada for avoiding pitfalls.

I think its time to consult another install company. You are going to need a friend down there someone who can drop in and do an inspection, go over whhat you paid and possibly testify in court.

Online advice is problematic and i like manuals and conversations with the engineers or someone i know has it together more than myself. This equipment is expensive!

The inverter system monitoring computer should have load compensated state of charge indication. This is muy important for more accurate state of charge determination while a system is active and the battery  is under ebb and flow or slam-on chargedown from its ac charger. This is the only way to get dood disconnect reconnect setpoints co-ordinated also, so again i didnt read the whole manual (i dont even think i could get that inverter here as nifty as it is, but it seems to have the stuff, so it must be load compensated...... not always.

A one line drawing from your permiting or design package should show us the relationship of energy flows based on equipment connections, wire sizes all that.

Reason i say this is because that battery and its inverter is the real heart of the system. The panels are just a charging source. It is important to give it a stout and controlled charge current and you cannot get it from two or three independent inverter/chargers all with the individual capacity to make the batteries blow gas and other unwanted behavior.

Communication between the two inverters will avoid having any of their combined charging sources overdo it. 75a max.(industrial use) cant remember the other spec, like 60, i think. 50a is conservative without dragin wagon to get there. You might kindof want it to happen quick as reasonable, or get there calmly, it depends on your inverter firmware and use.

frank li wrote:

Graham Chiu wrote:

frank li wrote:
I know the term off grid is strong and mesmerizing, but i totally get that you are not trying to be or operate off grid.

That is very similar to what your system was doing though. I mean, why are we even talking about batteries being flat after the electric water heater runs if it is not in fact operating with grid assist like a generator in an off grid?

So i am still missing something.

So, when the system is topping up the hot water, it should not be drawing all of the 3kW from the battery?  Is this something that I can change or should change?

No, mahaps not. Ifits money younare after then you need an accountant to depreciate the battery replacement cost or however they would term that and figure out how many cycles it is worth at the 29 and 8 cents.

If anything, if your electric heater or any other appliance or load will destroy the battery or excellerate wear beyond the beancounters number, it gets put on a utility load panel outside the reach of the inverted battery power seasonally permanently or in an automatic fashion. Of it outstrips battery costs over whatever payback scheme.....

i guess really unless they have seperate utility meters for water heating/ac etc., through the utility it is a matter of not using the electric heater or leaving it the way it is and accepting the shortfall.

You should be able to adjust the system to not crank itself dead trying to do so.

One more thought. The operation of your system in total, including the extra occupancy might just accept the 20 cent deficit and allow more of the system to backfeed. You might get more monetary offset depending on how much more power flows through the system. You might lose 15 percent or more energy on storage and retrieval....so we are back to accountants again.

Bengi brought a great item and im not willing to do the head exploding labor of breaking your system down for this excersise, but as a general rule of thumb, you would want 1 to 1.5 times your daily kWh usage in battery capacity.

I say 2 times. I cant help it its the battery lover in me. The entire industry and us poor folk with budget limitations are drastically undersizing the battery in these systems to the detriment of enjoyment of use and the industry as a whole.

There is backup operation, aging of the battery over as short a time as 2-3 years, new appliances, etc., to consider.ignoring this wont make it go away......well itl make the battery leave the house early!

Its why there is a misunderstanding about battery reliability, "its the weak spot or the device in renewable systems that is not ready yet, so ill wait..................................... another ten years to install our dream."  Or " you cant fool me, batteries and solar is a stupid idea, who would rely on a failure prone battery"

A total misunderstanding. A properly designed battery system is likely one of the most reliable devices any of us come into contact with. People are just not giving the design care and budgetary room fot them to show you what thay can really do.

Frank

Frank, thanks for the above advice.  I'm going to hassle this company to give me more information on this install, and ask them about switching to NW orientation if they plan to move the panels anyway.

I can't depreciate anything since it's a family home and not a business.  And it would be another NZD10,000 to double the battery bank size so that's not going to happen anytime soon.

Graham Chiu wrote:Frank, thanks for the above advice.  I'm going to hassle this company to give me more information on this install, and ask them about switching to NW orientation if they plan to move the panels anyway.

I can't depreciate anything since it's a family home and not a business.  And it would be another NZD10,000 to double the battery bank size so that's not going to happen anytime soon.

! I just meant account for it in dollars. Pump and dump the battery vs just deal with 9 cents instead of 20 something sometimes.

Dont cut them slack. People doing it themselves or other co-op no major biggie, profiteers though, take it to them!

Just for interest I ran the NZ NIWA calculator on various configs as it apparently accounts for cloud data at one's location

Date	Az 45, Tilt 30	Az 45, Tilt 23	Az -37, Tilt 41	Az -37, Tilt 23
21/3/2019	4.13	4.13	4.15	4.2
21/6/2019	1.75	1.68	1.87	1.71
21/8/2019	2.59	2.56	2.68	2.61
21/10/2019	4.68	4.75	4.54	4.79
21/12/2019	5.81	6	5.51	6.05
Totals kW-hr/m2	18.96	19.12	18.75	19.36

The first column is where I am at present, So, it would seem I am likely to maximize solar production by switching the panel orientation 90 deg to north west, and lowering the tilt angle.  I read somewhere that where I am true north is 20 deg west of magnetic north.  Optimizing for winter I presume only applies to people who are off grid.

Graham Chiu wrote:Just for interest I ran the NZ NIWA calculator on various configs as it apparently accounts for cloud data at one's location

Date	Az 45, Tilt 30	Az 45, Tilt 23	Az -37, Tilt 41	Az -37, Tilt 23
21/3/2019	4.13	4.13	4.15	4.2
21/6/2019	1.75	1.68	1.87	1.71
21/8/2019	2.59	2.56	2.68	2.61
21/10/2019	4.68	4.75	4.54	4.79
21/12/2019	5.81	6	5.51	6.05
Totals kW-hr/m2	18.96	19.12	18.75	19.36

The first column is where I am at present, So, it would seem I am likely to maximize solar production by switching the panel orientation 90 deg to north west, and lowering the tilt angle.  I read somewhere that where I am true north is 20 deg west of magnetic north.  Optimizing for winter I presume only applies to people who are off grid.

Sure, now you can add what will not fit in the battery and not be consumed and point the thing away from your wallet!

frank li wrote:

Graham Chiu wrote:Just for interest I ran the NZ NIWA calculator on various configs as it apparently accounts for cloud data at one's location

Date	Az 45, Tilt 30	Az 45, Tilt 23	Az -37, Tilt 41	Az -37, Tilt 23
21/3/2019	4.13	4.13	4.15	4.2
21/6/2019	1.75	1.68	1.87	1.71
21/8/2019	2.59	2.56	2.68	2.61
21/10/2019	4.68	4.75	4.54	4.79
21/12/2019	5.81	6	5.51	6.05
Totals kW-hr/m2	18.96	19.12	18.75	19.36

The first column is where I am at present, So, it would seem I am likely to maximize solar production by switching the panel orientation 90 deg to north west, and lowering the tilt angle.  I read somewhere that where I am true north is 20 deg west of magnetic north.  Optimizing for winter I presume only applies to people who are off grid.

Sure, now you can add what will not fit in the battery and not be consumed and point the thing away from your wallet!

Then you will see what im talking about. Its not a huge disparity amd has to be donee for the whole year, mont to month( billing schedule). At your location it could be quite correct, to do as you are looking to do nd phils figure was 400whr/day.

Self consumtion to avoid export is a rather new game and i could be totally wrong here. I think most of your gain is the azimuth change.

Maximizing production in months that will overproduce is not it either. So its probably on the cross quarter....

frank li wrote:Maximizing production in months that will overproduce is not it either. So its probably on the cross quarter....

Now if you had an off grid sized battery and a grid tie sized array, you could stick it to them most any month.

Cross quarter again. Just intuition.

At my current expenditure of power I suspect there's no battery bank I can afford that's ever going to enable me to go off grid.
The only way would be if I were to rent out my house as an AirBnB over the winter, and spend the winter in the northern hemisphere!

Yeah, go for it. I still suggest breaking it down to a month by month. You would have to simulate it to be sure. Max array output is so not taking the whole system into account...... if you are trying to keep from exporting at 8 cents

There are way more columns to figure this one. After a year, you will have a nice datalog from actual operation and the system is what it is.

My other horse is dead, so im going to go kick that one a bit.

frank li wrote:Yeah, go for it. I still suggest breaking it down to a month by month. You would have to similate it to be sure. Max array output is so not taking the whole system into account...... if you are trying to keep from exporting at 8 cents

There are way more columns to figure this one. After a year, you will have a nice datalog from actual operation and the system is what it is.

My other horse is dead, so im going to go kick that one a bit.

Sorry to say, but your system was likely better off as a simple grid tie at least saving money wise.

I have another question while waiting for my solar co to contact me.

Since my panels are at 30 deg tilt, there's a big empty gap on the rails behind the panels.  Does anyone use reflectors to transfer the energy coming from behind the panels to reflect onto the panels behind the current row?  I gather planar reflectors can increase electrical output by 20-30% but I don't know if anyone is actually doing this in the wild.

https://www.academia.edu/16836963/Photovoltaic_System_Performance_Enhancement_With_Non-Tracking_Planar_Concentrators_Experimental_Results_and_Bi-Directional_Reflectance_Function_BDRF_Based_Modelling

I've read that the potential problems with reflectors is that you potentially shorten the life of the panels by heating up the panels too much.  This isn't the reflector pushing out infrared onto the panel but heat generated from the electricity increase flowing through the panel.  Those reflectors work while there is already sun on the panel.  But here I'm asking about reflecting light onto panels that would otherwise be in shade as the sun is now behind.

frank li wrote:
ly alter the actual result.

Like a battery..... "its a two stage charger" there is a logical deficit if i take that on its face.

I consulted the manual, and it says it's a 3 stage charger.  In stage 1 the battery is charged with a constant current till the voltage reaches the charge absorb voltage to reach stage 2.  Then it's charged with a constant voltage til the charge current is more than 1A or the duration of stage 2 is 2 hours.  Then it enters stage 3 for float.

So, I have no idea why the tech told me it is a 2 stage charger.  Which makes me wonder about these voltage settings.

I'm convinced that the solar hot water system is stuffed.  Maybe I need to replace 15 evacuated tubes.  It was only 6 years ago that it was installed.  So, that means I can potentially take the hot water out of the  battery charging.

And now I find that there's an electricity retailer that offers one hour of free electricity per day, just not at peak hours.  So, I could potentially force the battery to recharge from the grid during that hour.  There are two settings on the inverter to force charge from the grid.  The only thing is, they don't buy back solar.  But now we're in autumn, I suspect exporting of power is going to drop off.  Currently I'm importing 8kWh, and exporting 9kWh due to mismatch in battery bank size.

So, one month later they finally came to adjust the panels.  Rather than separating them, they dropped all three ( not just the first two ) rows to 20 deg as it was much less work than moving them of course.  And why drop all three?  So, it would look better!

But now one inverter is reading solar generation is negative!!  WTF?

Negative solar generation...is that like feeding power into the sun?

Just a wee update - the solar hot water vendor finally got some evacuated tubes and arranged for a local plumber to install them.
I needed all 24 tubes replaced.  They were less than 8 years old  But I do get the HWC up to about 30 deg C now in mid winter.

Just an update on this thread.

The system had to be disabled on the 28th December 2020 after I woke up to smoke coming from the basement.
Two fire engines later, and lots of CO2 as well as powder from their cannisters the heat kept increasing.  The lines company electrician then went onto the roof to pull all the cables from the panels so that the solar power wouldn't keep feeding the fire.

It was repaired yesterday but one of the hybrid inverters needs to be replaced.
The cause of the fire was water in the DC isolator which was on fire. This is a common cause of rooftop fires in solar installations in Australia but my DC isolators are in the basement.  We had thought rain water was being directed by conduit from the roof into the isolator, and the guys who came to repair installed grommets everywhere that they should have been before.  But water was found in the connection that penetrates the wall of the basement from the rooftop.  This had not been sealed fully.  I asked them to install service loops to stop water from entering the switches again, and they said it wasn't necessary as long as it was installed correctly.  Luckily I wasn't dependent on the solar system and still had access to the grid.