Question for the solar panelists.

[joebog1]

The origional poster did not say how many wheels he has on his shed, aka man cave. 24 volts is hopeless UNLESS you have an engine with a whacking big alternator to pick up the overcast days.
From my very limited understanding of UK ( never been there, will never go as the aged pension is just NOT THERE ) They MOSTLY have overcast, rain, misery, lots of mould, with a rare sunny day that might reach a staggering 20 degrees C.
Australia has many days over 30 in most areas ( I was born up top of snowy mountains, I know cold and misery ) it also has 200 days straight, of pure unrestricted sunshine, in MOST of the other areas.
Even south australia can be 10 degrees air temp and blazing sunshine for 12 or 13 hours that will burn your skin off in five minutes without full body cover clothes, a large brim hat ( Hold the corks ) and sunscreen.
I would suggest that the OP has a few trees about his shed, or at least shrubs that will sheild the panel ( s ) for some time during the day. Solar panels drop to about 10% of output by blocking ONE SINGLE cell array on a single panel.
Thats what the blocking diodes do !!.

He ( the origional OP ) has not done a power analysis, where we know how much energy ( in watts ) his equipment will consume. So lets assume his man cave has a very modest inverter welding machine Mig.
How long will a 2000 watt chinese heatsink style invereter run that little baby welding machine?. How many lights, EVEN LED lights does he need/use?. An aircompressor at the same time of course.
Perhgaps a fan to aid air purity. Computer??.

HOW much power does he consume?.
How long is he fiddling in the shed ?.
What equipment is on when he is IN the shed ?.
How much sunshine does he get per day ?.
What angle can he mount his solar panel array ?.
Will the structure, roof, rack system, designed to hold solar panels be facing the sun ?.
Does he have a backup generator ( The equivelent to your truck alternator ).
How many, and what size are the batteries/battery bank ratings ?


Blobber has the right idea!!!!.
I am NOT saying spend a million quid, I am saying we ( I ) need a list of what he needs, what will run at any time.
He needs supply a breakdown of his energy usage before we can even "Have a guess ".

Respectfully,

Joe

 

[8ob]

misery, lots of mould, with a rare sunny day

He ( the origional OP ) has not done a power analysis, where we know how much energy ( in watts ) his equipment will consume. So lets assume his man cave has a very modest inverter welding machine Mig.
How long will a 2000 watt chinese heatsink style invereter run that little baby welding machine?. How many lights, EVEN LED lights does he need/use?. An aircompressor at the same time of course.
Perhgaps a fan to aid air purity. Computer??.

HOW much power does he consume?.
How long is he fiddling in the shed ?.
What equipment is on when he is IN the shed ?.
How much sunshine does he get per day ?.
What angle can he mount his solar panel array ?.
Will the structure, roof, rack system, designed to hold solar panels be facing the sun ?.
Does he have a backup generator ( The equivelent to your truck alternator ).
How many, and what size are the batteries/battery bank ratings ?


Blobber has the right idea!!!!.
I am NOT saying spend a million quid, I am saying we ( I ) need a list of what he needs, what will run at any time.
He needs supply a breakdown of his energy usage before we can even "Have a guess ".

Respectfully,

Joe

Lets leave SWMBO out of this


Power requirements a 24v supply capable of running an electrolysis tank and charge truck batteries at the same time during daylight hours. Got a big flat roof area right next to where all this needs to happen, its a long way from there to where the incoming supply is which is why I would like this to be stand alone.

 

[toddy]

im only up the road (didcot) and have got one one my buildings running offgrid currently, if you wanted to pop over and have a look and a chat about systems you welcome to come over.
i started with a very small system as a test and went from there. and now have a good sized system.

 

[J1nx]

I did solar installations for more than 30 years.
If you dont wanna put the money in, you wont get nuthin out.
for knighty, second hand solar panels !! How many do you want ?.
They are one of the largest pollution problems we have in Australia right now.
They have a VERY finite life!!! Thats finite, not infinite. Somebody suggested MPPT controller !!! . YES perfect suggestion.
24 volts is peeing in your own pocket, minimum I will do is 48 volts as a minimum, and preferably 60 volts.

I have been roused on before for telling the truth!!. I hope this in ONE truth thats at least checked up on.

With respect

JoeView attachment 389410

Wow, some major differences between countries and not just the weather. Over here the faulty commercial panels are palletised in 25s, wrapped and collected. They need to be kept secure before collection or they will get nicked!

Bob, any specs of the truck charger? Really need to know what current (or Watts) it requires.

If you just want the electrolysis bit you really only need the panels, some wire and some form of isolator. That can be very simple, just gets more complicated depending on control required.

 

[sako243]

As per usual things have blown out of proportion here.

At least when I spoke with Bob over the weekend he wasn't interested in powering the electrolysis tank off the grid if he could help it. The trickle charging of trucks is a new one requirement since we spoke. The idea was he could hook up some stuff in the big electrolysis tank and just leave it, if it took a week to process who cares because he doesn't have that much time anyway.

He also has, or had (before he weighed them in), a load of old batteries going spare. I did something similar for my missus's stable before I ran mains to it - an old battery from a Land Rover that I didn't trust to start but would hold charge happily. A small panel (I mean really small) keeping that topped up and some 12V floodlights for lighting. Lasted quite happily for months.

From my research after chatting to Bob an electrolysis tank even of his size won't benefit from going above 24V and consume no more than 20A. In fact you usually need to limit the current and quite often (from research) to a few amps. So well within the capabilities of an old battery.

So excluding the trickle charging all he really needs is a low voltage cut out (readily available) to prevent unwanton damage to the batteries and a current limit device for the tank.

Whilst tying into the grid etc would be beneficial long term it won't happen because Bob doesn't have the time, nor probably wants to spend the moment.

 

[pressbrake1]

This is my experimental off grid system at home.
I have three phase at home and run my lathes at home. At my industrial unit there’s 75kw grid tied.
The system at home except on dark days does the hot water, washing machine , dishwasher and on sunny winter days the condensing tumble drier which will also heat the kitchen.
System consists of a vevor mppt £140
12 twenty year old panels facing west , six 400watt panels facing south but at the worst angle possible.
Then there’s the big mistake hybrid inverter
I bought it from photonic universe during the madness for double the price it should be and standby is 250watt!!! Total poop
I’m getting a victron when I can spare ££
I now run a single phase compressor off it for blowing off parts instead of running a big kaiser for that which was madness.
If the mrs is in a sunny day will charge the car and still do other tasks
I caught the last couple of weeks of summer and had to turn off one array as there was more power than I knew what to do with.
Suggestion to the mrs to get a night job so the car could charge during the day wasn’t well received!
Hopefully this year I’ll connect a 12kw three phase grid tied. Been waiting since August for a smart meter

 

[reb78]

This is my experimental off grid system at home.
I have three phase at home and run my lathes at home. At my industrial unit there’s 75kw grid tied.
The system at home except on dark days does the hot water, washing machine , dishwasher and on sunny winter days the condensing tumble drier which will also heat the kitchen.
System consists of a vevor mppt £140
12 twenty year old panels facing west , six 400watt panels facing south but at the worst angle possible.
Then there’s the big mistake hybrid inverter
I bought it from photonic universe during the madness for double the price it should be and standby is 250watt!!! Total poop
I’m getting a victron when I can spare ££
I now run a single phase compressor off it for blowing off parts instead of running a big kaiser for that which was madness.
If the mrs is in a sunny day will charge the car and still do other tasks
I caught the last couple of weeks of summer and had to turn off one array as there was more power than I knew what to do with.
Suggestion to the mrs to get a night job so the car could charge during the day wasn’t well received!
Hopefully this year I’ll connect a 12kw three phase grid tied. Been waiting since August for a smart meter

View attachment 389427 View attachment 389428

I would love to do this. I have no idea where to start and dont trust the plethora of fly by night installers that appear to be out there. DIY also makes it more affordable and possible!

 

[pressbrake1]

I would love to do this. I have no idea where to start and dont trust the plethora of fly by night installers that appear to be out there. DIY also makes it more affordable and possible!

Having the separate off grid system has been so useful
We had a power cut from Thursday night to yesterday because of a underground hv failure
I couldn’t run my machines but the house ran as normal as we had bright days

 

[Gareth J]

Regarding output, putting details into pvgis gives a good indication. A very rough rule of thumb, for 1000w of unobstructed South facing panels, expect ~1000kWh per year. Expect 75% of the day's production to come between 10:00 and 14:00 and 75% of total production to come between March and August.

Bob's nearly flat roof will be significantly different though. Again, get onto pvgis to estimate.

If there is currently no 240v AC to the shed at all, and you won't put in a cable, and you don't want to run DC back to a 240v supply, then no, there is no point thinking about inverters. Unless you'd like to have a 240v AC supply from the setup that is. Off-grid style. However, don't be concerned that a grid tied system needs to go next to the meter. It doesn't.

 

[reb78]

Regarding output, putting details into pvgis gives a good indication. A very rough rule of thumb, for 1000w of unobstructed South facing panels, expect ~1000kWh per year. Expect 75% of the day's production to come between 10:00 and 14:00 and 75% of total production to come between March and August.

Bob's nearly flat roof will be significantly different though. Again, get onto pvgis to estimate.

If there is currently no 240v AC to the shed at all, and you won't put in a cable, and you don't want to run DC back to a 240v supply, then no, there is no point thinking about inverters. Unless you'd like to have a 240v AC supply from the setup that is. Off-grid style. However, don't be concerned that a grid tied system needs to go next to the meter. It doesn't.

So if I have a cable from my meter by the house to my shed 200m away, can I use that cable to feed back to my house if all the the gubbins is also in the shed and I am using electric in the shed?? I think of electric as a one way thing (i.e. supply this end, use that end) but think I am very wrong?

 

[J1nx]

As per usual things have blown out of proportion here.

At least when I spoke with Bob over the weekend he wasn't interested in powering the electrolysis tank off the grid if he could help it. The trickle charging of trucks is a new one requirement since we spoke. The idea was he could hook up some stuff in the big electrolysis tank and just leave it, if it took a week to process who cares because he doesn't have that much time anyway.

He also has, or had (before he weighed them in), a load of old batteries going spare. I did something similar for my missus's stable before I ran mains to it - an old battery from a Land Rover that I didn't trust to start but would hold charge happily. A small panel (I mean really small) keeping that topped up and some 12V floodlights for lighting. Lasted quite happily for months.

From my research after chatting to Bob an electrolysis tank even of his size won't benefit from going above 24V and consume no more than 20A. In fact you usually need to limit the current and quite often (from research) to a few amps. So well within the capabilities of an old battery.

So excluding the trickle charging all he really needs is a low voltage cut out (readily available) to prevent unwanton damage to the batteries and a current limit device for the tank.

Whilst tying into the grid etc would be beneficial long term it won't happen because Bob doesn't have the time, nor probably wants to spend the moment.

He could simply connect a PV panel or two straight onto the electrolysis terminals, would only work when reasonably bright but it doesn’t get any easier if times no matter.

 

[Gareth J]

So if I have a cable from my meter by the house to my shed 200m away, can I use that cable to feed back to my house if all the the gubbins is also in the shed and I am using electric in the shed?

Correct. You don't need to use anything in the shed for it to work though.

200m is a long cable though.....the voltage drop on it at full system power might be limiting.

 

[reb78]

Correct. You don't need to use anything in the shed for it to work though.

200m is a long cable though.....the voltage drop on it at full system power might be limiting.

Its 3 phase supply 35mm2 if that makes a difference but i thought that was excess detail for here!

 

[MattF]

Lets leave SWMBO out of this

 

[Gareth J]

Its 3 phase supply 35mm2 if that makes a difference but i thought that was excess detail for here!

Same calculations required for volt drop for drawing from at the shed end as "pushing" with an inverter the other way.

 

[joebog1]

here is an easy way to calculate whats needed

TheBackShed.com - System Design

Some basic maths to size up the system components of a renewable power system.

www.thebackshed.com

If it simply the electrolysis tank, all that needs be done is connect the panels directly to the tank.

Joe

 

[Barlidge]

So lets assume his man cave has a very modest inverter welding machine Mig.
How long will a 2000 watt chinese heatsink style invereter run that little baby welding machine?. How many lights, EVEN LED lights does he need/use?. An aircompressor at the same time of course.
Perhgaps a fan to aid air purity. Computer??.

HOW much power does he consume?.
How long is he fiddling in the shed ?.
What equipment is on when he is IN the shed ?.


Respectfully,

Joe

Oh my! You really don't know our 8ob

 

[sako243]

The small welding set is 350A...
The main compressor is a bigish 3ph 250+l one.

 

[joebog1]

Thanks Ed, you have the same taste in humour as myself!!

Joe

 

[joebog1]

What is 8ob please Barlidge ?

Joe