Off grid solar

[intheshire]

Can anyone recommend an off grid mttp battery charge controller for my solar panels please, I'm going to be charging my powersafe 170ah AGM batteries, 24v

2 strings of 8x250w panels in series

Per panel:
VOC: 60.50v
VMP: 50.60v
ISC: 5.3A
IMP: 4.94A


Any help appreciated

 

[binky]

Victron is probably your best bet for off grid inverters/ charge controllers.

 

[intheshire]

Victron is probably your best bet for off grid inverters/ charge controllers.

They don't make anything big enough

The max voltage on one string is just shy of 540v

I found this but wow look at the price
https://www.morningstarcorp.com/products/tristar-mppt-600v/

 

[binky]

They don't make anything big enough

They don't make anything big enough

The max voltage on one string is just shy of 540v

I found this but wow look at the price
https://www.morningstarcorp.com/products/tristar-mppt-600v/

They do, but you won't like the price

What are you actually trying to achieve with an off grid system?

 

[intheshire]

They do, but you won't like the price

What are you actually trying to achieve with an off grid system?

My old dad is on an oxygen concentrator machine , . Not panicking or anything but with the news is taking about black outs / brown outs , longer term power cuts. I'd like to keep him going + keep the lights on , maybe the fridge

We've got a few days worth of back up batteries, but I'd like to be able to charge them from the solar array when the grid is down . I was very surprised when I found out grid tie solar systems stop working during a power cut , I understand why safety ect. But still seems silly being sat in the dark with a couple of £1,000 worth of PV system on the roof doing nothing

 

[johnb2713]

My old dad is on an oxygen concentrator machine , . Not panicking or anything but with the news is taking about black outs / brown outs , longer term power cuts. I'd like to keep him going + keep the lights on , maybe the fridge

We've got a few days worth of back up batteries, but I'd like to be able to charge them from the solar array when the grid is down . I was very surprised when I found out grid tie solar systems stop working during a power cut , I understand why safety ect. But still seems silly being sat in the dark with a couple of £1,000 worth of PV system on the roof doing nothing

Most inverters have an emergency output that is live when the grid goes off. Essential items can be powered from this and the panels will keep recharging the batteries.

 

[binky]

My old dad is on an oxygen concentrator machine , . Not panicking or anything but with the news is taking about black outs / brown outs , longer term power cuts. I'd like to keep him going + keep the lights on , maybe the fridge

We've got a few days worth of back up batteries, but I'd like to be able to charge them from the solar array when the grid is down . I was very surprised when I found out grid tie solar systems stop working during a power cut , I understand why safety ect. But still seems silly being sat in the dark with a couple of £1,000 worth of PV system on the roof doing nothing

Most grid tied inverters/ battery systems have a UPS output of around 3kw

 

[monkey5]

Most inverters have an emergency output that is live when the grid goes off. Essential items can be powered from this and the panels will keep recharging the batteries.

This was mentioned before. Is it live all the time or just when there's a cut?

 

[intheshire]

Most inverters have an emergency output that is live when the grid goes off. Essential items can be powered from this and the panels will keep recharging the batteries.

Now that I'd be interested in! Could save me a small fortune?

It's an SMA sunnyboy

Most grid tied inverters/ battery systems have a UPS output of around 3kw

Ah the batteries are separate from the grid tie solar system, they are in my shed right now on a big smart charger

 

[johnb2713]

Ah the batteries are separate from the grid tie solar system, they are in my shed right now on a big smart charger

We'd really need more info to advise. Why are the batteries not connected to the inverter? Is the inverter a Hybrid inverter i.e. can it charge the batteries from the grid? Perhaps the model number of inverter would help.
As an example, my Growatt inverter has the UPS output of 3kW that Binky mentioned, it remains live with grid attached or not and will therefore maintain the supply to the circuits connected to it. The inverter can charge from the grid or from solar.

 

[intheshire]

We'd really need more info to advise. Why are the batteries not connected to the inverter? Is the inverter a Hybrid inverter i.e. can it charge the batteries from the grid? Perhaps the model number of inverter would help.
As an example, my Growatt inverter has the UPS output of 3kW that Binky mentioned, it remains live with grid attached or not and will therefore maintain the supply to the circuits connected to it. The inverter can charge from the grid or from solar.

Hi John so we have a 4kw solar array on the roof - it was all here when we moved in. It's south facing, 16x250w panels, 60.5v, two strings of 8 panels. Grid tied with a SMA sunnyboy 3.6kw inverter , it looks a lot like this :




And then separate from the grid tie system , in my shed , I have a few bits and bobs, mobility scooter batteries / leisure batteries, inverters, mains chargers, 1x250w solar panel with 10a mppt , a Rutland wind turbine I'm yet to set up

I also have a small bank of powersafe 12v 170a AGM batteries (set up as 24v atm) - these are the ones I'd really like to charge from the panels during power cuts .


Do all the growatt grid tied inverters have this off grid mode ? Which one have you got pls ,

I'm not against having the grid tie inverter changed

 

[johnb2713]

Hi John so we have a 4kw solar array on the roof - it was all here when we moved in. It's south facing, 16x250w panels, 60.5v, two strings of 8 panels. Grid tied with a SMA sunnyboy 3.6kw inverter , it looks a lot like this :

View attachment 14369


And then separate from the grid tie system , in my shed , I have a few bits and bobs, mobility scooter batteries / leisure batteries, inverters, mains chargers, 1x250w solar panel with 10a mppt , a Rutland wind turbine I'm yet to set up

I also have a small bank of powersafe 12v 170a AGM batteries (set up as 24v atm) - these are the ones I'd really like to charge from the panels during power cuts .


Do all the growatt grid tied inverters have this off grid mode ? Which one have you got pls ,

I'm not against having the grid tie inverter changed

I have a Growatt SPH6000 connected to my solar PV and a 7Kw Growatt battery. I also have a Victron Multipluss II GX which I am using soley as a powerwall connected to 14kW LifeP04 cells. Both inverters are grid tied, when the panels are producing and their attached battery is full, immersion up to temp and cars charged etc, if it starts to export the Victron starts to charge the big battery.
I cant say if all inverters have the emergency output, certainly all of the ones I've looked at do.

 

[intheshire]

I have a Growatt SPH6000 connected to my solar PV and a 7Kw Growatt battery. I also have a Victron Multipluss II GX which I am using soley as a powerwall connected to 14kW LifeP04 cells. Both inverters are grid tied, when the panels are producing and their attached battery is full, immersion up to temp and cars charged etc, if it starts to export the Victron starts to charge the big battery.
I cant say if all inverters have the emergency output, certainly all of the ones I've looked at do.

Thank you John, I was looking at that inverter.

That's a good set up, how long do you think you could last off grid ?

 

[johnb2713]

Thank you John, I was looking at that inverter.

That's a good set up, how long do you think you could last off grid ?

I can run a whole day quite comfortably with the 2 batteries including heating (heatpump) etc. Our normal base load is around 475w so 21kWh should give us nearly 2 days. I havent purchased any electricity for car charging since the end of May, it's all been done from my roof.

 

[stuboy]

You will need to search for Hybrid inverter, many companies do them. Hang on here's a link 4U:-
https://www.cleanenergyreviews.info/hybrid-solar-inverter-comparison
I've got a Solis Hybrid for what that's worth ;-)

Enjoy trolling the specs
Stu

 

[binky]

Hi John so we have a 4kw solar array on the roof - it was all here when we moved in. It's south facing, 16x250w panels, 60.5v, two strings of 8 panels. Grid tied with a SMA sunnyboy 3.6kw inverter , it looks a lot like this :

View attachment 14369


And then separate from the grid tie system , in my shed , I have a few bits and bobs, mobility scooter batteries / leisure batteries, inverters, mains chargers, 1x250w solar panel with 10a mppt , a Rutland wind turbine I'm yet to set up

I also have a small bank of powersafe 12v 170a AGM batteries (set up as 24v atm) - these are the ones I'd really like to charge from the panels during power cuts .


Do all the growatt grid tied inverters have this off grid mode ? Which one have you got pls ,

I'm not against having the grid tie inverter changed

Ok, that inverter does not have UPS function. I would not change it as that could invalidate your FiT payments.

I would install an AC battery system, which usually consists of a hybrid inverter with no solar panels attached. It will still charge from spare solar energy, and also has the UPS function you need, although rearranging ccts to use that can be fun. Have a read of other battery posts on here, all the information is in those.

 

[intheshire]

Thank you both

 

[johnb2713]

Ok, that inverter does not have UPS function. I would not change it as that could invalidate your FiT payments.

I would install an AC battery system, which usually consists of a hybrid inverter with no solar panels attached. It will still charge from spare solar energy, and also has the UPS function you need, although rearranging ccts to use that can be fun. Have a read of other battery posts on here, all the information is in those.

Victron Multiplus II does exactly that.

 

[intheshire]

Victron Multiplus II

I'm off to the bank, see if they'll accept me for a second mortgage so I can buy one

 

[johnb2713]

I'm off to the bank, see if they'll accept me for a second mortgage so I can buy one

They're not cheap but they are designed for that job. I have the 48/5000 GX version which has all of the GX stuff built into it. There are some good prices around if you know where to look.

J