Posted by: @yachtsman

@derek-m My EV is not capable of V2G, but I wish it was.

The problem that Transparent is highlighting, is that there are limitations as to what consumers are allowed to do, with regard in particular to exporting to the grid. Having unexpected generation from wind, solar PV, battery installations or even V2G, is equally as bad as unexpected demand, since both have to be accommodated to maintain grid stability.

What Transparent is suggesting, is that by careful design, it is possible to maximise a system whilst remaining within the constraints imposed by the local DNO.

@derek-m Yes I appreciate that. I’ve explained my requirements to the supplier/installer who assures me there will be no issue meeting the needs of the DNO or getting approval. Particularly since I don’t intend to export. I intend using everything generated on home appliances and the EV.

obviously there will be several months & days when solar can not support the home or fully charge the battery, off peak will be used to maintain a fully charged battery which will then support the solar.

Posted by: @yachtsman

@derek-m Yes I appreciate that. I’ve explained my requirements to the supplier/installer who assures me there will be no issue meeting the needs of the DNO or getting approval. Particularly since I don’t intend to export. I intend using everything generated on home appliances and the EV.

obviously there will be several months & days when solar can not support the home or fully charge the battery, off peak will be used to maintain a fully charged battery which will then support the solar.

Whilst I try to fully utilise all the generation from my 4kW solar PV system, there are still days when I cannot do so and export to the grid. I think that you may find that you will have similar situations.

@derek-m You may well be right Derek, after all I’ve never owned a PV system before & I have this idea it’s not going to be too difficult, & I enjoy a challenge.

Getting the EV almost 2 years ago and now having PV + battery system installed is a fun game to me. I will of course report back after the DNO have responded and when I’m up & running. I’ll probably be asking a lot more questions then. 😀

@yachtsman I'd personally suggest getting air conditioning. You'll use it basically only in the summer and it'll soak up excess PV so you get to cool your house... For free. We love our AC

@batalto  Honestly we don’t need AC, the house is lovely & cool when it’s hot outside & quickly warms up when the temperature drops. Even in winter we rarely run our heating for more than about 30 mins every couple of hours to maintain a comfortable  to the ctemperature.

I think as long as I can make the EV available to charge  I hope I can dump any excess into the RV.

Posted by: @yachtsman

I’ve explained my requirements to the supplier/installer who assures me there will be no issue meeting the needs of the DNO or getting approval.

The installers for my storage battery were equally confident. However it actually took 7 months to get G99 approval to add the string inverter. 😧 

The DNO will consider a number of factors about which an installer may know nothing. These include:

• the distance between you and your substation
• the cross-sectional area of the feed cable from that substation
• the number of houses on the same feed between you and the transformer
• how much unallocated capacity remains on the transformer
• the variation (daily or seasonal) of the voltage supplied to your house

These factors are fed into a formula which provides the maximum export permitted (or the power available to you if the application is for Low Carbon Technology). However, the DNO engineer can then change some of the input values to check how much dependence can be placed on the result.

For example if none of the houses between you and the substation have yet got any LCT devices, an allowance might be made. This could warrant the granting of a G99/100 export on the grounds it is highly likely that LCT applications will shortly be forthcoming, in line with the regional average.

Unlike other members of the public I have been given access to WPD's network mapping tools so I can actually see the data about cable feeds for example. This helps enormously in trying to understand why some grid connections are refused.

In response I have undertaken that I will have this sort of discussion with members of the public on Fora and in person. The whole point is to increase public knowledge about these issues.

@transparent  I’ve received the system schematic & I was wrong about the hybrid inverter.

I don't think you're entirely 'wrong' about the status of the inverter @yachtsman

It all depends what is meant by hybrid.

The storage battery is DC-connected to that inverter, and can be charged either by solar or from the grid. I'll return to that point in a moment.

The designer has provided one point of connection to the grid. This will require G98 approval, and will be subject to the DNO's appraisal of whether they accept the specified current-limiting for grid export. There are two main possibilities:

• Grid export configured to zero; all stored charge to be used within the home. DNO will check that the export limitation system is on the ENA Approved list (mine wasn't!).
• Grid export limited to 3.68kW (16A). This does at least allow you to export some electricity on sunny days if the battery is full, or if the system 'knows' that it will be full at some time later that day. Although theoretically possible, I'm not aware of any control system which yet implements that 'look-ahead' feature.

What you don't have in this system design is the ability to run anything if the grid is 'down'. Everything relies on the inverter picking up the 50Hz grid frequency and synchronising to it. If the off-grid provision is what you regard as an essential factor in the description 'hybrid', then this design doesn't fulfil that intention.

The system which I'm developing does have that off-grid functionality. I'll be able to run a number of 230v 50Hz AC-connected devices during power-outages, and also operate all DC-connected essentials such as landline-phone, internet router, WiFi, CCTV security etc.

However, let me point out here, and hope that the Moderators pick this up...

I am liaising with senior DNO network engineers regarding the prototype system I'm developing.

1. certain parts of a hybrid off-grid system may still need notification to a DNO, even if they appear to have no direct grid connection
2. some safety features which I'm incorporating are not currently stipulated within UK regulations, and I firmly believe that they should be. Your house-insurer may think similarly!
3. a proportion of the required component parts, particularly relating to safety, are not readily available in the UK. Just because there's a YouTube clip showing someone who's found a work-around does not mean that it's safe, effective or efficient to follow that route.

This is all very much at prototype stage. It 's entirely likely that some parts of my approach will need to be packaged into a 'product', tested, certified and sold commercially. That's expensive... but then so is electricity!

I want a system which allows consumers to defend themselves against energy poverty by drawing on cheap-rate electricity and solar/wind/hydro supplementing it if possible.

That differs from what you may wish to attempt, @yachtsman

Posted by: @transparent

I don't think you're entirely 'wrong' about the status of the inverter @yachtsman

It all depends what is meant by hybrid.

The storage battery is DC-connected to that inverter, and can be charged either by solar or from the grid. I'll return to that point in a moment.

The designer has provided one point of connection to the grid. This will require G98 approval, and will be subject to the DNO's appraisal of whether they accept the specified current-limiting for grid export. There are two main possibilities:

• Grid export configured to zero; all stored charge to be used within the home. DNO will check that the export limitation system is on the ENA Approved list (mine wasn't!).
• Grid export limited to 3.68kW (16A). This does at least allow you to export some electricity on sunny days if the battery is full, or if the system 'knows' that it will be full at some time later that day. Although theoretically possible, I'm not aware of any control system which yet implements that 'look-ahead' feature.

What you don't have in this system design is the ability to run anything if the grid is 'down'. Everything relies on the inverter picking up the 50Hz grid frequency and synchronising to it. If the off-grid provision is what you regard as an essential factor in the description 'hybrid', then this design doesn't fulfil that intention.

 

The system which I'm developing does have that off-grid functionality. I'll be able to run a number of 230v 50Hz AC-connected devices during power-outages, and also operate all DC-connected essentials such as landline-phone, internet router, WiFi, CCTV security etc.

However, let me point out here, and hope that the Moderators pick this up...

I am liaising with senior DNO network engineers regarding the prototype system I'm developing.

1. certain parts of a hybrid off-grid system may still need notification to a DNO, even if they appear to have no direct grid connection
2. some safety features which I'm incorporating are not currently stipulated within UK regulations, and I firmly believe that they should be. Your house-insurer may think similarly!
3. a proportion of the required component parts, particularly relating to safety, are not readily available in the UK. Just because there's a YouTube clip showing someone who's found a work-around does not mean that it's safe, effective or efficient to follow that route.

This is all very much at prototype stage. It 's entirely likely that some parts of my approach will need to be packaged into a 'product', tested, certified and sold commercially. That's expensive... but then so is electricity!

I want a system which allows consumers to defend themselves against energy poverty by drawing on cheap-rate electricity and solar/wind/hydro supplementing it if possible.

That differs from what you may wish to attempt, @yachtsman

Hi Transparent,

Are you developing something similar to the SMA system?

Similar thinking @derek-m but different approach.

Theirs operates like a UPS. They have an Automatic Transfer Switch that feeds power from the storage battery to the mains devices when there is a grid failure.

They also require connection to an external, internet-based management/control system.

Firstly I want to hide the complexity beneath the bonnet. The consumer may want to understand technicalities when buying/installing such a system, but it should operate out-of-sight & out-of-mind on a daily basis. Many of those on the UK's Priority Services Register would be unable to understand the operation of the SMA monitoring/reporting system, but those account for a very high proportion of the UK population in energy poverty.

I also want a system that can operate according to user preferences set according to

• price bands on a ToU tariff
• the amount of renewable energy in the mix

That leaves in the hands of the consumer (not the Energy Supplier!) how much they're prepared to pay for greener electricity. It's a sliding-scale, not a boolean decision!

Posted by: @transparent

Similar thinking @derek-m but different approach.

Theirs operates like a UPS. They have an Automatic Transfer Switch that feeds power from the storage battery to the mains devices when there is a grid failure.

They also require connection to an external, internet-based management/control system.

Firstly I want to hide the complexity beneath the bonnet. The consumer may want to understand technicalities when buying/installing such a system, but it should operate out-of-sight & out-of-mind on a daily basis. Many of those on the UK's Priority Services Register would be unable to understand the operation of the SMA monitoring/reporting system, but those account for a very high proportion of the UK population in energy poverty.

I also want a system that can operate according to user preferences set according to

• price bands on a ToU tariff
• the amount of renewable energy in the mix

That leaves in the hands of the consumer (not the Energy Supplier!) how much they're prepared to pay for greener electricity. It's a sliding-scale, not a boolean decision!

 

Hi Transparent,

From what I gather the SMA system is not just like a UPS, but actually allows any output from a solar PV system to continue to provide power for inhouse use.

Reading through the SMA manual it would appear that the system operates quite automatically on grid failure, and does not require any external control.