johnb2713
Well-known member
From what I have read from the OP he really hasnt understood off grid 'v' grid tie. I feel he will be making a big mistake going for an off grid inverter.
DIY solar install
- Thread starter tony gh
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From what I have read from the OP he really hasnt understood off grid 'v' grid tie. I feel he will be making a big mistake going for an off grid inverter.
Hello all
thanks for the replies they have been interesting, in respect to how much I think it will cost I have an idea already but I would be interested to hear how much you think it will cost. I thought £12,000.00 +scaffolding or 12+ 20% increase over a week or more + scaffolding was a lot for an off grid setup.
I do not have a large house and I am able to limit my use to a great extent, I certainly won't be using 5kw to cook my Sunday dinner. I would be interested to hear from anyone who is off grid if there are any here.
many thanks for the input
regards
Tony
thanks for the replies they have been interesting, in respect to how much I think it will cost I have an idea already but I would be interested to hear how much you think it will cost. I thought £12,000.00 +scaffolding or 12+ 20% increase over a week or more + scaffolding was a lot for an off grid setup.
I do not have a large house and I am able to limit my use to a great extent, I certainly won't be using 5kw to cook my Sunday dinner. I would be interested to hear from anyone who is off grid if there are any here.
many thanks for the input
regards
Tony
Hawkwind
Member
Hi, I am no electrician, but presently going through the process of getting battery storage added to my PV, which is 3.6kw had for10 years.
Someone may correct me but, what you are wanting "off grid" is different to what you are doing "grid tied".
From what I understand you will also need to notify your DNO with G98/99 or 100 depending on size and capacity and have it signed off by qualified electrician.
The invertor would have to be anti islanding.
That is if you are wanting it to all legal of course, if you ever sell up.
Someone may correct me but, what you are wanting "off grid" is different to what you are doing "grid tied".
From what I understand you will also need to notify your DNO with G98/99 or 100 depending on size and capacity and have it signed off by qualified electrician.
The invertor would have to be anti islanding.
That is if you are wanting it to all legal of course, if you ever sell up.
Hi Hawkwind
I too am not an electrician.
I am using panels to store power in 2 lithium Ion batteries and then using them to power stuff in the home on a separate consumer unit from that in the electric cupboard. I am not connecting to my consumer unit from the electric company and therefore have no tie to the grid.
I will use a separate supply from the house to add a backup for the batteries on cheap rate overnight electric, this is a plug in on the side of the cabinet containing the inverter charger etc. and can be timed to come on overnight I do not see that powering my own stuff will need notification to the DNO as I am using a separate source of power not the grid. Maybe I am wrong, I would be interested to see if that is the case. I am sure someone will tell me.
Thanks for the reply.
Hawkwind
Member
Yeah I get that, but you will need to check that the inverter doesn't send power back down the line that you are connecting to the grid, if there is a power cut overnight when you are charging, if not the correct inverter with anti islanding, that's what could happen, it's something you will need to double check.
An inverter is not like a battery charger, it can send power both ways.
Hello Hawkwind
I will have to have a look at this, it was not something the supplier mentioned given that the inverter is designed to plug in via the mains. Perhaps there is a way to install a reverse current diode into the line that is going to be used to act as a backup charging supply? I will also have a word with the supplier to check as I can't tell from the spec if it is anti islanding. Thanks for the reply
I will have to have a look at this, it was not something the supplier mentioned given that the inverter is designed to plug in via the mains. Perhaps there is a way to install a reverse current diode into the line that is going to be used to act as a backup charging supply? I will also have a word with the supplier to check as I can't tell from the spec if it is anti islanding. Thanks for the reply
Hawkwind
Member
No problem, I'm going with a victron multiplus-ii, that has anti islanding built in, but you can get a stand alone unit but they are not cheap.
I was going with eon to get battery storage, but its taken 6 months and the contractor didn't turn up for the appointment, rescheduled and they turned up with the wrong inverter.
I've cancelled with them, was going to cost £5500 for a 8.2kwh Givenergy system.
I'm getting all the stuff my self, then get local sparky to install and commission.
Will be saving about £1500.
Like you said in earlier post, don't mind paying but they are taking the p****.
Hi Hawkwind
I am getting a pre-built cabinet with everything in and the supplies are via external plugs on the cabinet. The main out then goes to the home appliances vie another consumer unit and the standby power in through the other plug. Do you know the models of standalone units as in the event the conversol v7 is not anti islanding I may need one.
regards
tony
I am getting a pre-built cabinet with everything in and the supplies are via external plugs on the cabinet. The main out then goes to the home appliances vie another consumer unit and the standby power in through the other plug. Do you know the models of standalone units as in the event the conversol v7 is not anti islanding I may need one.
regards
tony
Hawkwind
Member
I was looking at at victron unit.
hi Hawkwind
I have spoken to the supplier and they have assured me that it is technically impossible for the inverter to put power back into the grid. I did look at the above unit but to be honest there must be an easier way to shut off the supply to the inverter in the event of a power cut.
It only needs something that stays on when it has power and goes off when the supply is cut. I have used stuff in the past where you turn the item on and depress a lock in switch to keep it on and if the power goes off it cuts the power. A bit like a trip switch. I will have a bit more research into things and I am sure I will come up with something suitable.
I have spoken to the supplier and they have assured me that it is technically impossible for the inverter to put power back into the grid. I did look at the above unit but to be honest there must be an easier way to shut off the supply to the inverter in the event of a power cut.
It only needs something that stays on when it has power and goes off when the supply is cut. I have used stuff in the past where you turn the item on and depress a lock in switch to keep it on and if the power goes off it cuts the power. A bit like a trip switch. I will have a bit more research into things and I am sure I will come up with something suitable.
johnb2713
Well-known member
Pretty much all the way through this thread youve been very insistant on having an off grid inverter rather than a grid tied inverter. Surely if this is the case you have any issues with it feeding back into the grid, it wont happen?
There's a little more to it than that, it must not reconnect for 3 mins in the event of a grid failure. G100/99 grid tied inverters meet this spec, as well as other requirements.
johnb2713
Well-known member
For an off grid inverter?
Hawkwind
Member
An off grid invertor would have no connection what so ever to the grid. That's where the confusion is, that the OP is wanting off grid, but to top up with grid power, so it would be grid tied.
johnb2713
Well-known member
Thats isnt my understanding........
None Grid Tied / Off Grid
My understanding is that all of the loads are connected to inverter only and inverter can several sources of power including grid / generator / solar / wind turbine / batteries. It works with or without a grid supply present
Grid Tied
The inverter is connected to the household supply and can modulate its output voltage so the supply is taken from the inverter rather than the grid. It wont work without a grid supply being present
Have I got this wrong????
Hawkwind
Member
Both of those diagrams are connected to the grid, hence grid tied.
Its irrelevant where the solar power goes, wether to batteries or inverter, the invertor is tied to the grid.
Off grid is where there is no connection whatsoever to the property.
This may be the reason the original OP had a problem with the company that gave the quote and what he was wanting, they could not do it as it was not an off grid system.
Its irrelevant where the solar power goes, wether to batteries or inverter, the invertor is tied to the grid.
Off grid is where there is no connection whatsoever to the property.
This may be the reason the original OP had a problem with the company that gave the quote and what he was wanting, they could not do it as it was not an off grid system.
Hawkwind
Member
johnb2713
Well-known member
I'm not convinced, the grid tie aspect is synchronising the inverter output to the voltage and frequency of the grid so it can then increase voltage to feed appliances. Heres a wiki definition:
"Grid-tie inverters convert DC electrical power into AC power suitable for injecting into the electric utility company grid. The grid tie inverter (GTI) must match the phase of the grid and maintain the output voltage slightly higher than the grid voltage at any instant. A high-quality modern grid-tie inverter has a fixed unity power factor, which means its output voltage and current are perfectly lined up, and its phase angle is within 1 degree of the AC power grid. The inverter has an on-board computer that senses the current AC grid waveform, and outputs a voltage to correspond with the grid. However, supplying reactive power to the grid might be necessary to keep the voltage in the local grid inside allowed limitations. Otherwise, in a grid segment with considerable power from renewable sources, voltage levels might rise too much at times of high production, e.g. around noon with solar panels."
As above
[QUOTE}
Off grid is where there is no connection whatsoever to the property.
[/QUOTE]
I agree when you 'Off Grid' in terms of property, but if say it in terms of inverters you will have an AC IN, AC OUT etc, Off Grid for inverters means the output is isolated from the grid and output runs independently of the grid
This is where I think the OP has got it wrong and a grid tied inverter would be much better
Hello to all who have replied.
Just to clear up one thing. My system is separate from the consumer unit in my home and the inverter will supply separate outlets for the appliances inside the house. The additional backup power supply that is available on the system can be derived from a generator or from a lead from a socket in the house (cable spec to be calculated before this) It is not permanently connected to the grid in any way, merely when I choose to plug in a lead for a boost to the batteries.
The original company that looked at the install was not interested as it was probably not something they are used to doing (i.e no meter change etc).
If I connected my backup permanently then yes I can see it would be grid tied but if you are connecting a backup source from an outlet in the home does this really constitute grid tied? My supplier has told me that the inverter cannot export power back down the line to the grid in any way so I would have thought (and I am happy to be proved wrong) that this would not cause any issue with the grid in the event of a power outage, I am guessing the inverter would just stop charging the batteries until the power came back on?
I am in effect charging my solar batteries the same way you would charge a laptop.
Just to clear up one thing. My system is separate from the consumer unit in my home and the inverter will supply separate outlets for the appliances inside the house. The additional backup power supply that is available on the system can be derived from a generator or from a lead from a socket in the house (cable spec to be calculated before this) It is not permanently connected to the grid in any way, merely when I choose to plug in a lead for a boost to the batteries.
The original company that looked at the install was not interested as it was probably not something they are used to doing (i.e no meter change etc).
If I connected my backup permanently then yes I can see it would be grid tied but if you are connecting a backup source from an outlet in the home does this really constitute grid tied? My supplier has told me that the inverter cannot export power back down the line to the grid in any way so I would have thought (and I am happy to be proved wrong) that this would not cause any issue with the grid in the event of a power outage, I am guessing the inverter would just stop charging the batteries until the power came back on?
I am in effect charging my solar batteries the same way you would charge a laptop.
I was looking at a Growatt offgrid inverter manual the other day. It has the option of charging from the grid, which I was a little surprised at, but I don't think it backfeeds from what I can gather.
