Solar PV Hints, Tips & Troubleshooting

antoinolachtnai

Sir Liamalot wrote: »

For intents and purposes is can be. We could send wind to France and get sunlight in return later that day.

Think bigger send it to France cut out the middle man. We have to get over this islander mentality. Once it's on the mainland it can go to China on HVDC. Then it's way more interesting with differential daylight hours.

The cost of building transmission is immense.

An interconnector will be built to France because that is the cost of keeping the European project going. There'll only be .7 GW there. If we built a bigger interconnector where would it connect into? We don't have that much transmission in place to connect it to, even within Ireland.

There is great resistance (not the electrical type) to building transmission even here, a politically stable and prosperous place where everybody knows one another. We haven't built any significant transmission in years, even though we are crying out.

There are many other practical problems with building the pan-eurasian transmission system you envisage.

Most of them.


-- graph of renewable proportions in year--

That is a very different statistic. Those aren't grids. Those are countries. A great deal of that renewable electricity is synchronous (nuclear and hydro). Those countries are parts of vast AC connected grids.

You seem to have decided what the model for the whole grid should be without doing any analysis that can be scrutinised. You dismiss other people's analysis even though you apparently don't know the significance of the difference between synchronous and asynchronous power.

I can't beat pure solar on bang for buck with any alternative.
We do not build off-grid around a battery we build it around the generators with a battery. You are doing it right when you are not using the battery. This significance of the battery is misunderstood. What good is a cup without a water source?

Exactly! Both an off-grid setup and the Irish grid is based on stored energy which can be drawn upon as needed. The energy is stored in chemical form as oil or gas, stored either in a tank or in the ground.

This is exactly what we are trying to get away from. We are trying to find an alternative way to have energy available when we need it.

So does the grid but cheaper

It might appear that way, but the grid only has capacity because the dispatchable generators of various sorts provide capacity to the grid.

Why would I support the grid when they're short-changing me, increasing the wear and tear and have they not got their own storage?

The grid isn't a privately owned thing. It is a commons. If everybody takes from it, then it just won't work. The fact that you don't agree with the way the grid is run or allocates resources today doesn't change that.

This does not fit an economic or ecological debate. As needs must when the Devil drives.

I don't know what to say about that.

Agreed but this is not a concern of the micro-generator and there is such a low uptake of renewables in this country, we have an awful lot of hydrocarbons to reduce use of before that's ever an issue.

As things stand, wind sometimes has to be curtailed or constrained. It happens frequently enough. So it is not true to say this is not an issue. It is definitely an issue.

Pardon me but there's an awful lot better ways to spend it, before we even get started with all the chancers hiking the install prices way above their value.

Well, prices are going to be higher than the straightforward cost of the install, for the simple reason that there is going to be a marketing and sales cost to be recovered. That's the nature of rolling out a mass consumer product. It's a fair comment that it might be a waste of money.

Power on the network is a sellable and more valuable commodity than what we're doing with it.

It's worth 4c a kWh maybe. Once there's a load of it on the grid, say 1.5 GW, it'll probably be worth less.

ESB import open market value.

The ESB (electric ireland) price isn't an open market value necessarily. They sell electricity at all different prices.

You mean the wholesale price that electric ireland pays for electricity and that ESB powergen gents paid for selling electricity? Day-ahead price, which is a 'true' market price in the sense that there is open bidding and offering)? Imbalance price? Would you be happy enough to be paid (really pay) a negative price?

I don't mind paying for less coal burning. I mind paying for other peoples' green credentials that could perform better overall by throwing half of their hardware away.

For domestic retrofit PV, a lot of this money won't go on gear at all. It will go on four things, heights insurance, scaffolding, sales/service and marketing. I don't see how you can do the projects at any scale without these costs.

That's all very well if it makes people engaged in the whole process.

unkel

Sir Liamalot wrote: »

For intents and purposes is can be. We could send wind to France and get sunlight in return later that day.

This.

Europe is a great example of how we can maximise interconnecting. In a decade or so Spain needs to have the PV capacity of many times their own needs. Ireland needs to have the wind capacity of many times our own needs. Norway hydro, France nuclear. You get the picture.

Interconnectors are the "batteries" we need most and are most economical. Hydro storage is next. And somewhere after that is using batteries that we already have (EVs). Dedicated grid attached battery storage for our over production is far down the line. Somewhere slightly ahead of producing hydrogen with that same excess

antoinolachtnai

antoinolachtnai wrote: »

The cost of building transmission is immense.

An interconnector will be built to France because that is the cost of keeping the European project going. There'll only be 1 GW there. If we built a bigger interconnector where would it connect into? We don't have that much transmission in place to connect it to, even within Ireland.

Can we not get a loan as you say yourself we've paltry wind and nowhere to put it? We've a massive resource and we're not developing it.

antoinolachtnai wrote: »

There is great resistance (not the electrical type) to building transmission even here, a politically stable and prosperous place where everybody knows one another. We haven't built any significant transmission in years, even though we are crying out.

Too much NIMBY. Yet people are happy with CO2 pumping into the atmosphere alternatives. I can't understand it myself. If people have a problem with turbines then take the main fuse outtov the consumer unit is my stance.

antoinolachtnai wrote: »

There are many other practical problems with building the pan-eurasian transmission system you envisage.

I thought it was underway. Seems that there's a wee gap between Russia and India

antoinolachtnai wrote: »

That is a very different statistic. Those aren't grids. Those are countries. A great deal of that renewable electricity is synchronous (nuclear and hydro). Those countries are parts of vast AC connected grids.

You seem to have decided what the model for the whole grid should be without doing any analysis that can be scrutinised. You dismiss other people's analysis even though you apparently don't know the significance of the difference between synchronous and asynchronous power.

Nope just oversimplifying it. HVDC will dominate transmission. I hear ya knockin'. Grand so 50hz HVAC. The point was more use the international grid not a battery is all. It certainly wasn't me claiming to have a better take on the how.


The boundary is getting muddy on are we talking domestic, national or international.

What I am pointing out or trying to is that putting a battery in every house is lossy and expensive. There'd be more clean power for better value for everyone if we generate and utility store. As regards the transmission losses the storage can be local to point of use rather than big remote plants, utility is in a much stronger position to maximise viability.

antoinolachtnai wrote: »

Exactly! Both an off-grid setup and the Irish grid is based on stored energy which can be drawn upon as needed. The energy is stored in chemical form as oil or gas, stored either in a tank or in the ground.

This is exactly what we are trying to get away from. We are trying to find an alternative way to have energy available when we need it.

Agreed. I don't think we are going about it very well by these tiny tribute batteries in people's closets. (Oh how we will laugh in a coupla days when my numbers are in and I'm eating humble pie..:pac: )


I've 20% losses outtov the gates atm and that's very favourable because the results are contaminated with power on demand. The unit I'm using is 95% claimed efficiency by the way. I've tested it at 79% round trip at C1.5 with unity power factor.

antoinolachtnai wrote: »

It might appear that way, but the grid only has capacity because the dispatchable generators of various sorts provide capacity to the grid.

I understand. We'd be dispatching less of them with more solar and less closet batteries.

antoinolachtnai wrote: »

The grid isn't a privately owned thing. It is a commons. If everybody takes from it, then it just won't work. The fact that you don't agree with the way the grid is run or allocates resources today doesn't change that.

er..no I'm saying that without the closet batteries we'd have more power on the network hence less burning coal. This is all. I did get sidetracked with the whole why are we so inept at RE generation though.

antoinolachtnai wrote: »

I don't know what to say about that.

It means that our standards change in times of need. If the grid is down then the >€7k of hardware sitting in my workshop is priceless.

antoinolachtnai wrote: »

As things stand, wind sometimes has to be curtailed or constrained. It happens frequently enough. So it is not true to say this is not an issue. It is definitely an issue.

Oh dear, oh dear...new can of worms. Why are we braking turbines? Can we not have a dump load like a [dare I say it] hydrogen electrolysing plant [gets ready for a flaming].
Sure terrible idea but is there not a profitable way to dump the power instead of helicoptering engineers to nacelles to apply brakes?

antoinolachtnai wrote: »

Well, prices are going to be higher than the straightforward cost of the install, for the simple reason that there is going to be a marketing and sales cost to be recovered.

You know I've noticed all my prefered brands don't advertise?
It's just the mediocre ones feel they have to.

antoinolachtnai wrote: »

That's the nature of rolling out a mass consumer product. It's a fair comment that it might be a waste of money.

Indeed. My stance remains unchanged. Grid tied solar is a far better deal than grid tied batteries with solar. I will eat my words publicly and with pride if the numbers I have after the weekend show me I'm incorrect to believe so.
It's better for the network, it's better for the planet, it's a better deal all round. If it's marginal and has applicational merits i will broadcast that too.

antoinolachtnai wrote: »

It's worth 4c a kWh maybe. Once there's a load of it on the grid, say 1.5 GW, it'll probably be worth less.

4c a kWh more in the right direction than a battery cost.

Do you not find it odd that nobody has any comprehensive data on their system performance. Sure people have apps to show them what the power is doing but not the whole picture of what went into the device compared to what came out?
Not even the sellers and distributors.
Why am I the only one asking?
Is that not an important detail?

antoinolachtnai wrote: »

Would you be happy enough to be paid (really pay) a negative price?

Are you mad? I've plentya better things to do with it that sell it for negative equity.

antoinolachtnai wrote: »

For domestic retrofit PV, a lot of this money won't go on gear at all. It will go on four things, heights insurance, scaffolding, sales/service and marketing. I don't see how you can do the projects at any scale without these costs.

If PV only has to pay for PV. Not PV + battery doesn't that half the expense if the system is designed to suit the load profile?
Spare me the marketing. I can tell more from a datasheet and a meter.
In fact needing to prop a product up with marketing is very telling indeed.
Also I'm not interested in the warranty, I don't buy junk. So can I have that 10% back too?

antoinolachtnai wrote: »

That's all very well if it makes people engaged in the whole process.

Provided they're not being taken for a ride.

daughy

unkel wrote: »

It's all relative. You will learn once you start playing with this stuff. A good BMS that will protect my battery costs more than my battery cost. So investing in one would be a terrible waste of money. A half decent BMS doesn't cost much and will protect the battery from overvolt, undervolt, etc. and it will cut off the battery when the cell imbalance becomes too big. It will do a very poor job at balancing the cells though. And my inverter already has the job of overvolt, undervolt, etc. protection and my battery is fused for short circuits / over current, etc. I had a half decent BMS but I decided I would personally take over its function. Liam got it in one

I haven't got around to installing a lithium system on my setup, or even a lead acid at this stage, I have installed lead acid in the past on a different system and that was 5 years ago, only a small system, 24 volt 220 amp hours, just a charge controller and a 2kw inverter, but it's just for running a fridge. Liam are you testing the efficiency of the hybrid inverter or the lithium cells themselves?
I'm still learning about lithium and its characteristics and if its actually worth spending the large upfront costs, plus alot of people that have these closet batteries are in a residential environment, not all people live on farms with acres and acres of land and fields beyond the eye can see to have as many panels as one would desire. I didn't choose a rail mounted system on my roof as my roof is what keeps the rain from falling on my head, I just don't trust drilling into my roof, and the uplift over time from wind, I'm not telling anyone else what to do, just my opinion. Plus you can clean the panels easier on the ground.. And if one goes bad you can just add easily swap it out without getting a roofer. Anyway, just my opinion.
Has anyone here except for Liam run an off grid setup as even a test for a couple of days with lithium? Would be nice to hear your thoughts on the charge and discharge rates and are you happy with your results. If you had lead acid in the past can you see different results?
More capacity, longer run time, less maintenance, anything else one can think of you can post it here. Don't be afraid of the big bad wolf, his bark is worse than his bite ha

daughy

I'm searching for a simple battery operated WiFi hot water thermostat to connect the probe to my hot water tank to keep an eye on the temperature when away from home, I'm not interested in getting a hive or nest as that's too expensive, just something I can check on phone for the temp of the tank, has anyone got any recommendations. Something cheap I hope.

daughy

Well I found something cheap if anyone else where looking for something like this.

its on amazon with the probe,
https://www.amazon.co.uk/dp/B0813CN56X/ref=cm_sw_r_em_apa_fab_1ESGFb4ZG7N5J

daughy

daughy wrote: »

Liam are you testing the efficiency of the hybrid inverter or the lithium cells themselves?

System viability and applications. Testing with an end goal of competing with diesel.


I actually mostly got into Li-ion to prove that the masses were drinking too much kool aid.
Lead and Li-Ion have the same efficiency and practical applications as eachother. Li-ion has about a 2% efficiency lead.

My next test to to dedunk MPPT being significantly better than PWM if you match the solar array to the battery voltage correctly.

daughy wrote: »

plus alot of people that have these closet batteries are in a residential environment,

My 20kWh fit on a rack less than 1m³

daughy wrote: »

Has anyone here except for Liam run an off grid setup as even a test for a couple of days with lithium?

I'd say that's highly unlikely given the cost and the tiny size.


Anyone can buy 60kWh of lead traction for the same price as 5kWh of li-ion. Anything less won't cut it for an off-grid house.

daughy wrote: »

Would be nice to hear your thoughts on the charge and discharge rates and are you happy with your results.

I can charge lead at C3 and discharge at C1. Given the size of a lead battery for the cost it performs every bit as well as a closet battery.

daughy

Sir Liamalot wrote: »

My next test to to dedunk MPPT being significantly better than PWM if you match the solar array to the battery voltage correctly.



My 20kWh fit on a rack less than 1m³

I remember using a PWM controller for my first setup and it was when I was starting out, small 12 volt battery, testing purposes only, the 100 watt panel 12 volt, at the time was getting around 20-30 watts from the PWM.
So I stepped out up to an mppt and the results where significant. 60 to 70 watts at least..
What would be the purpose Liam of doing such a test?
If PWM are aware they can modify the voltage to suit the panels and vice versa wouldn't they have told everyone to do it and not lose money to the competition mppt?
I do like lead acid for price but not for the maintenance that comes with it. The weight, the size, the gasses they release, the constant filling of water, the over charging to keep the plates clean every month or so, cleaning the terminals from corrosion, dangerous acid to name but a few.
But I suppose its a hobby for some.
Will be interesting to hear if your theories are correct. I'm guessing Elon Musk will have to modify the tesla to incorporate all that extra weight

12v panels are a poor choice for 12v applications they're 22Voc.
If the voltage is correct in the first place an MPPT algorithm is redundant.

The purpose of the test is to see if you can get the same results with less expense & to demonstrate that taking what you read on tinternet as fact is quite misleading. At best MPPT is 15% better not 30% unless you go way off the range on panel to battery voltage compatibility.
I reckon I can get it down to <5%

You can automate lead maintenence for far less than li-ion costs. Recombinant watering kits and stirrers are not expensive.
There's a hellova lot going on in a BMS that make li-ion "plug and play", the same can be done with lead yet people like to compare apples and oranges to justify the expense.
Setting fire if you charge them below 0°C is quite a drawback.


The li-ion lightweightness is beneficial for mobile aplications where the motor has to pull the payload. House batteries generally only move on the install day.
Don't get me started on that charcter. Batteries that sit down without the internet and have internal heaters running all Winter long. Spoofer.

daughy

Sir Liamalot wrote: »

12v panels are a poor choice for 12v applications they're 22Voc.
If the voltage is correct in the first place an MPPT algorithm is redundant.



Setting fire if you charge them below 0°C is quite a drawback.

I agree, musk is quite the spoofer, but he's doing quiet well.
I did start out with just a simple 12 volt 100 watt panel, and a 12 volt battery, PWM. I actually still have it charging to monster size batteries, two grown men just to carry 1 of the batteries, 5 years ago I might add.
Then they made panels with 40 volts open circuit so this 6kwp limit from the esb is really limiting people on the amount of panels they can have, I can safely have 15, 350 watt longis on the 5kw hybrid.
Do you mean the lithiums catching fire if charged below 0 degrees? I just thought the bms would disconnect at low voltage?
And have a temperature sensor connected to the battery?

Some do, some don't. Some throttle the charger, some have heaters.
Indoors and operating temperatures help a lot. There's been a few DIY campers & boats burned down alright.
Unattended with solar....boom!

garo

The elephant in the room Liam has completely ignored - when going on his anti-battery rant - is the mismatch in the time of solar production and consumer demand. An HVDC to France will help a lot but not entirely as Irish peak demand will come when the sun has set or is low in the horizon over most of Europe.


BTW, I totally agree that not every PV install in Ireland has to be accompanied with a battery and an HVDC connector to France is likely a better use of our money. But without storage - either a dozen Turlough Hills or a hundred thousand consumer batteries - there is no squaring the circle. Solar and wind are intermittent and peak demand times are not necessarily when you get peak production.

daughy

He posted on the solar quote forum, i think he needs a break from our drama 😂.
Not stalking him ha

garo

garo wrote: »

The elephant in the room Liam has completely ignored - when going on his anti-battery rant - is the mismatch in the time of solar production and consumer demand.

I'm not anti-battery. I am anti-closet battery on a viability basis.
To repeat myself utility batteries are a great idea. Domestic closet batteries are not. Refute all you want but where's your evidence that it is a good idea? It's all anecdotal rebutals.

garo wrote: »

But without storage - either a dozen Turlough Hills or a hundred thousand consumer batteries - there is no squaring the circle. Solar and wind are intermittent and peak demand times are not necessarily when you get peak production.

Think bigger;
Tidal lagoons.
Compressed gas caverns.
Bio-gas production.
Flow Batteries.
Carbon film batteries.
Pumped Storage.


Why are the only people on the uptake of li-ion the ones who don't measure their performance?
Would anyone bother if there wasn't a grant and a sales spin?
What are the rest of the 10 year more progressive world doing?


Here's my data so far. Read from it what you will. Please bare in mind that I'm using Swiss engineered hardware that is the parent of all these new fangled hardware boxes that are trying to copy it built down to a market pricepoint. It's got a nigh unheard of consistent efficiency across the load profile and a big bottomed transformer.
This is the highest efficiency I have seen what's more usual is 40% losses.


This is our test subject;




A 48V Studer XTM 4kVA dialled up to 60V with 3kWh usable LiFePO4 CalB cells.


Claimed 95% efficient.


After a series of days linked to 2.4kW solar and a back-feed set to 2A (including power factor) 24hour and a back-feed bleed of 180W.





88% efficient @ normal operation (power on demand with overnight back-feed)


Followed up with a more constrained test


Solar Gen on Sunday (seasonal shading issues)






Of which 1.7kWh went direct to load






4.24kWh - 1.69kWh = 2.55kWh went to battery charging.


of that 2.22kWh extracted from the battery after losses went to load.




87% efficient.




Well I'm impressed. Your mileage will vary.


Cost of this unit (ex-labour) could have bought me 19kWh more solar.

garo

Thanks for the results. I bet they are better than you were expecting.

I am all for utility scale batteries. And yes it's not just pumped hydro or Li-ion. Lots of other technologies in the mix.

But here's an interesting counter-point to the utility scale batteries good, dometic batteries bad narrative:

https://renew.org.au/renew-magazine/solar-batteries/solar-and-high-grid-voltage/

Ideally we'd have smart appliances that could use power when there is excess in the grid and switch off at peak times or when the wind dies down. But we'll be waiting a while for those and I wouldn't grudge people a few tens of thousands Li-ion batteries while we await the FiT.

The XTM can use frequency shifting to trigger appliances. I'm not begrudging anyone anything. Just make an informed decision. I have several more of these JFM boxes previous to this the efficiency and pricetag was a hellova lot lower.

[Edit] actually I reckon that's in off-grid operation only...I haven't tried it.

garo

garo wrote: »

Ideally we'd have smart appliances that could use power when there is excess

The old ImmerSun units had this feature. 2 x 3kW sequential PWM outputs and a 10A (?) relay.


They're all failing now at the input terminals and the FETs due to under-cooling.
If you find a good one they're going for ~£150


This new Eddi isn't half as good as the ImmerSun was.

daughy

I am just wondering if its possible to overcome this issue, I think it's possible to have panels on the same string but in different orientations, if I add Optimisers to the string is it possible.
My issue is with the shading in my back garden, the 5 panels I have facing east get the morning sun, if I add another 5 panels to that string and move that array west, I know there will be to much shading in winter as the sun is lower, I have a large shed that has a flat roof which can accommodate 6, 350 watt longi, if I add 5 Optimisers to that 5 panel east array should it not in theory bypass the 5 panels facing east when shaded at 2.30pm... Just a thought..

daughy

Or then again it could be cheaper to add Optimisers to the 10 panel west array when installed, whatever is shaded just add Optimisers.
Either way what do you guys think of adding Optimisers to different orientations

championc

You've somewhat lost me @daughy

If you are looking at East and West only, then all you need is a 2 MPPT inverter - each string will connect into the inverter separately. Your losses in winter from a bit of shade late in the day will never pay for the cost of adding optimizers.

But then you mention the shed. So are you planning on installing on it too ? If so, you may well be worth considering a second separate inverter

daughy

championc wrote: »

You've somewhat lost me @daughy

If you are looking at East and West only, then all you need is a 2 MPPT inverter - each string will connect into the inverter separately. Your losses in winter from a bit of shade late in the day will never pay for the cost of adding optimizers.

But then you mention the shed. So are you planning on installing on it too ? If so, you may well be worth considering a second separate inverter

Well I already have 2 strings on 1 inverter,
An East and south facing array, 5 panels each.
I'm limited by space on the south array, its met its limit, the east array has the other 5 panels, the new 5 panels would be on a flat roof of a shed but would get the west facing sun, not much of a tilt, only a flat roof, but constantly gets sun. Connected the east facing array to the new 5 panel array on top of the shed, and added 5 Optimisers to the east array, as soon as the sun leaves the east array at approx half 2 in the day, wouldn't the 5 panels on the shed activate or be activated without any interference from the shaded east array, as that's the purpose of Optimisers?

daughy

Unfortunately I can't add 5 panels to the east array as I would really take up more space in the garden, I would myself so it if I lived alone, but my wife wouldn't allow it

unkel

Would you not just get a dual input string inverter? Optimizers cost almost half as much as a panel and are not very long lasting (maybe 5-10 years if you are lucky), they generally are a terrible invesment unless you really have no other choice.

I bought one myself, but it was really cheap (about GBP30 incl shipping iirc) and it was just to play with

But but but Unkel a panel = two optimisers and wayyyyyyy more power. Re TOH forgiveness is easier get than permission....

daughy

See my dilemma is, in order to have a South, East and West array on my dual inverter, I would need to have 5 Optimisers on the east array so the west array doesn't get dragged down by the shading at approx 2pm.. Not sure I'm explaining it properly.. I just read on previous posts not to have different orientations on 1 string, if I just put 5 panels on the shed I'll have to buy another inverter and hire electrician to wire it up to the main board, plus more dc circuit breakers

unkel

Oh I see, 5E, 5S and 5W is the plan?

I think I saw some triple input string inverter somewhere, but I'm not entirely sure even if they exist if that would be a viable solution. Someone more knowledgeable might clear that up

daughy

unkel wrote: »

Oh I see, 5E, 5S and 5W is the plan?

I think I saw some triple input string inverter somewhere, but I'm not entirely sure even if they exist if that would be a viable solution. Someone more knowledgeable might clear that up

I appreciate your reply unkel, as much as that would be an ideal setup, I am nearly sure 1 string South, 1 string East and West with Optimisers in between should do it. Can't see why not as Optimisers keep the flow going while any other panel is shaded.

daughy

daughy wrote: »

I appreciate your reply unkel, as much as that would be an ideal setup, I am nearly sure 1 string South, 1 string East and West with Optimisers in between should do it. Can't see why not as Optimisers keep the flow going while any other panel is shaded.

For the 200 I was going to purchase for an extra wood ground mount, I can just use that for the Optimisers, I'll need rails but there not that expensive from solar City

championc

Do you get much output from the east ? I'm assuming your Wests are unhindered all day but your East are only able to work for what - 5 hours ??.

Personally, I'd fit your East and optimizers and go all in on south and west. If you insist keeping the East, I'd go East on one and South + West on the other, with maybe your optimizers on the south if it will be shaded at all

daughy

championc wrote: »

Do you get much output from the east ? I'm assuming your Wests are unhindered all day but your East are only able to work for what - 5 hours ??.

Personally, I'd fit your East and optimizers and go all in on south and west. If you insist keeping the East, I'd go East on one and South + West on the other, with maybe your optimizers on the south if it will be shaded at all

Ah, it took me a few times reading to understand, but I get you.
You mean link the east and south together on one string, optimise the east with the 5 Optimisers, and just use the west on the separate string.