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Solar PV Hints, Tips & Troubleshooting

DrPhilG

Well I've reached the point of driving everyone nuts on the PV quotes thread, and since I now have my system installed and running my endless questions no longer belong there.

So I figured I'd ask here, and also provide a home for others in the same boat, with general questions and advice on managing post-install.

My first question (of many) is how do people best manage their production in order to reduce grid export? Despite being overcast and miserable a fair bit of the day, I've produced 24kWh so far today, but ended up exporting 11.

Not too bad when we're home, as the wife did a few loads of washing and drying, put on the dishwasher etc.

But we're both at work tomorrow so other than a timed or remotely activated washer/dryer run we would end up exporting a lot more.

Extra battery capacity or a water diverter would help, but they don't tend to justify their costs in the long term.

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daughy

air wrote: »

The 3 strings of 10 are completely separate from one another, they don't combine in series anywhere.

So 3 Seperate strings, 10 panels each string, consisting of 350 watt panels each to make 3.5kwp on each string.

Overall kwp would be 350x30= 10.5kwp.
Is each string capable of allowing up to 600 volts dc input to the inverter?

If so then the 5kw solis hybrid has the exact same spec apart from the kW output.
If this is the case I was limiting the overall kwp
To 15, 350 watt panels at 40 volts open circuit each making 600 volts,
15x350=5.25kwp

If the inverter can handle 2 strings, of 15, 350 watt panels each at 40 volts open circuit then that changes the your overall kwp to 30x350=10.5kwp.
At 15x40= 600 volts

Is this wrong?

air

daughy wrote: »

Overall kwp would be 350x30= 10.5kwp.
Is each string capable of allowing up to 600 volts dc input to the inverter?

Yes, assuming the inverter specifies a maximum DC input voltage of 600V.

daughy wrote: »

If so then the 5kw solis hybrid has the exact same spec apart from the kW output.
If this is the case I was limiting the overall kwp
To 15, 350 watt panels at 40 volts open circuit each making 600 volts,
15x350=5.25kwp

If the inverter can handle 2 strings, of 15, 350 watt panels each at 40 volts open circuit then that changes the your overall kwp to 30x350=10.5kwp.
At 15x40= 600 volts

Is this wrong?

I'm sorry I'm having difficulty understanding the above section, I'm unsure if you are asking a question or making a statement.
If you are asking a question can you have another go perhaps.

Mickeroo

Anyone know how to set a minimum state of charge on a battery with a solis/pylontech system?

My battery seems to constantly discharge 80w or so through the night and in this cold weather it will sometimes charge off the grid to get it up to 20%, presumably to protect the battery. I want to try and set it so it won't discharge below 20% to begin with and doesn't discharge through the night when I'm on night rate anyway.

mp3guy

Mickeroo wrote: »

Anyone know how to set a minimum state of charge on a battery with a solis/pylontech system?

My battery seems to constantly discharge 80w or so through the night and in this cold weather it will sometimes charge off the grid to get it up to 20%, presumably to protect the battery. I want to try and set it so it won't discharge below 20% to begin with and doesn't discharge through the night when I'm on night rate anyway.

Are you only finding this in the cold weather? What temperature has it been getting to? According to the PDF here it works as cold as -20c http://en.pylontech.com.cn/pro_detail.aspx?id=114&cid=23

Mickeroo

Could be correlation not causation I suppose, the low state of charge might be the trigger more than anything.

daughy

air wrote: »

Yes, assuming the inverter specifies a maximum DC input voltage of 600V.

I'm sorry I'm having difficulty understanding the above section, I'm unsure if you are asking a question or making a statement.
If you are asking a question can you have another go perhaps.

Unfortunately I was under the impression the Solis hybrid max dc input was limited to 600 volts.
Up to 300 volts on one string, and 300 on the other, on the spec sheet for the inverter it didn't give any indication im aware of that it's up to 600 volts on each string..
All it says is max dc input 600v.
Very ambiguis

mp3guy

Mickeroo wrote: »

Could be correlation not causation I suppose, the low state of charge might be the trigger more than anything.

My batteries, different brand but lithium-based, were exhibiting strange behaviour when they got below 5c. Like discharging below the limit, then pulling a small amount of power to trickle charge while they were still very cold. It's probably to do with temperature.

air

daughy wrote: »

All it says is max dc input 600v.
Very ambiguis

That's all you need to know, its very clear then.
The strings are completely independent of one another, there is no combining of voltages from separate strings.
Post the specs of the inverter if you have them.

air

mp3guy wrote: »

My batteries, different brand but lithium-based, were exhibiting strange behaviour when they got below 5c. Like discharging below the limit, then pulling a small amount of power to trickle charge while they were still very cold. It's probably to do with temperature.

They probably have an integrated heater to prevent them dropping below zero. Lithium based chemistries can't be charged below zero due to the formation of dendrites which permanently damage the battery.

daughy

air wrote: »

That's all you need to know, its very clear then.
The strings are completely independent of one another, there is no combining of voltages from separate strings.
Post the specs of the inverter if you have them.

Here is the specs.

air

Clear as day then, 600V max input voltage (keep the number of panels * VOC under this figure, ideally leave some headroom.)
The string's total maximum power total voltage should be 100-500V to enable it to track.
These figures apply to each DC input independently, there is no division by number of MPPT inputs or anything of the likes, if there was it would say it in the data sheet.

daughy

air wrote: »

Clear as day then, 600V max input voltage (keep the number of panels * VOC under this figure, ideally leave some headroom.)
The string's total maximum power total voltage should be 100-500V to enable it to track.
These figures apply to each DC input independently, there is no division by number of MPPT inputs or anything of the likes, if there was it would say it in the data sheet.

Good to know air. Tnx for the help ðŸ‘

championc

Mickeroo wrote: »

Anyone know how to set a minimum state of charge on a battery with a solis/pylontech system?

My battery seems to constantly discharge 80w or so through the night and in this cold weather it will sometimes charge off the grid to get it up to 20%, presumably to protect the battery. I want to try and set it so it won't discharge below 20% to begin with and doesn't discharge through the night when I'm on night rate anyway.

Have you the option to set a schedule, to charge with 0w, between hh:mm and hh:mm. If so, this should stop charging and discharging. On the Sofar ME3000, it actually goes into Standby when you set it up like this

DrPhilG

Dammit, sun is out and I'm generating damn all.

Anyone got a link for a long brush to sweep off your panels?

mp3guy

I use one of these https://www.amazon.co.uk/gp/product/B07ZPHPMLG/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

unkel

mp3guy wrote: »

I use one of these https://www.amazon.co.uk/gp/product/B07ZPHPMLG/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

Over €100? :eek:

Doing some quick sums and not allowing any money for the time you are spending wiping the panels, that brush will pay for itself in roughly 87 years.

mp3guy

unkel wrote: »

Over €100? :eek:

Doing some quick sums and not allowing any money for the time you are spending wiping the panels, that brush will pay for itself in roughly 87 years.

A drop in the ocean compared to the PV investment over its life time. Seems fairly sturdy. I'm sure there's something cheaper out there, but I'm not arsed searching that hard to save a few euro.

unkel

The biggest saving is probably not spending any money on a brush and just let the snow melt naturally, that's my point :pac:

mp3guy

Some of us aren't obsessed with the pay back time of every little item involved. Or how many cents their time is worth doing something.

graememk

unkel wrote: »

The biggest saving is probably not spending any money on a brush and just let the snow melt naturally, that's my point :pac:

Mine are covered too.. but I can't even think of clearing them, far too high. And it's snowing again

Next time your in a hardware store/or similar keep an eye out.

But don't spend 100euro for a few days of the year in winter.

DrPhilG

Might break the low production record at this stage, even though its a gorgeous day.

South facing panels starting to clear but generation still zero.

West facing, ahh forget it...

mp3guy

DrPhilG wrote: »

Might break the low production record at this stage, even though its a gorgeous day.

South facing panels starting to clear but generation still zero.

West facing, ahh forget it...

Do you have a hose? Might be able to wash it off (assuming you bled it/it's not frozen).

unkel

mp3guy wrote: »

Some of us aren't obsessed with the pay back time of every little item involved. Or how many cents their time is worth doing something.

The obsessed are the people who do not think about money

mp3guy

unkel wrote: »

The obsessed are the people who do not think about money

Would be great if you were more forthcoming with your comments rather than speaking winky winky snide remarks. People who do not scrutinise cost benefit and payback time as much as yourself are obsessed, is that it? Or people who hold different opinions for what "value" means to them?

DrPhilG

mp3guy wrote: »

Do you have a hose? Might be able to wash it off (assuming you bled it/it's not frozen).

I got a stepladder and a brush and coaxed the last of it off the bottom. Not an option for the house panels though.

Quite the before and after though. 5 minutes or so apart either side of clearing the snow.

slave1

3m brush, should be plenty for you (you can use step ladder if required for extra reach), about £25 delivered to ROI

https://www.amazon.co.uk/Extending-upstairs-window-cleaning-SQUEEGE/dp/B005FBIF5G/ref=sr_1_1?dchild=1&keywords=roof+brush&qid=1611418478&s=kitchen&sr=1-1

unkel

mp3guy wrote: »

Would be great if you were more forthcoming with your comments rather than speaking winky winky snide remarks. People who do not scrutinise cost benefit and payback time as much as yourself are obsessed, is that it?

Relax man, just a bit of light hearted forum banter. Perhaps I should use more emojis

On a more serious note, it's fine of course to spend your money whatever way you want (not aimed at you) at renewable stuff. But I just like people to get good value and not be ripped off. A lot of people seem poor at doing any sums, they just presume something is good value or that they should go ahead because it's the right thing to do. I see that on some other social media a good bit - people spending €15k on a PV system with a battery and proudly boasting that it's great and saves them a fortune so well worth it, not realising it's only saving them a fraction of what they think it does - meaning the system will never pay for itself

mp3guy

unkel wrote: »

Relax man, just a bit of light hearted forum banter. Perhaps I should use more emojis

On a more serious note, it's fine of course to spend your money whatever way you want (not aimed at you) at renewable stuff. But I just like people to get good value and not be ripped off. A lot of people seem poor at doing any sums, they just presume something is good value or that they should go ahead because it's the right thing to do. I see that on some other social media a good bit - people spending €15k on a PV system with a battery and proudly boasting that it's great and saves them a fortune so well worth it, not realising it's only saving them a fraction of what they think it does - meaning the system will never pay for itself

I wonder is there a way to keep the latest info up front somewhere, oftentimes it's post in the quotes thread, rinse and repeat. Even a google sheet that people could plug their numbers into. They must be all the same sums every time.

There's a spectrum of adopters out there, some DIYers and value seekers like yourself, others wouldn't (or shouldn't) be trusted to DIY and happy to pay a third party, and others who would happily never make a return on the investment even if it's good value (enthusiasts I suppose). A one stop guide for folks would be ideal.

There's a wealth of info on here but it's hard to access. There's someone I know how did exactly as you said, massively overpaid for a system and it pains me to tell them.

championc

DrPhilG wrote: »

Now people can see what shading does to output

gomamochi1

Just got this from myenergie about the solar pv/ battery/ eddi conundrum that I am having=

'If it is an AC coupled battery we can work along side it, with it being a DC battery, we cannot measure the input and output of the battery. Therefore you have to clamp after the inverter meaning there is no way to differentiate between PV and DC Batteries for the eddi,

There is lots of people worldwide with a hybrid PV system with a DC battery, However we currently do not have a way of measuring the battery independently to the PV. '