DNO limitation and potential workaround

[Bob Smith]

Hello

I would like to share with you some thoughts and that you let me know what you think and what else I should consider.

The set: PV System 15kW. For simplicity let's assume 5kW facing East, 5kW facing South and 5kW facing West.
DNO does not authorize additional power to the grid and therefore 3.68kW is the only authorized power to be exported and the inverter will limit the export accordingly


Size the battery to store all the excess power which has not been consumed by the house (including heating hot water) and cannot be exported due to the limitation.
Then later when the panels no longer produce enough power and the house has enough power from the battery, the excess stored in the battery will slowly be exported to the grid (respecting the limit).

In other words, does it make sense with such an export limit and large system to send some of the electricity stored in the battery to the grid at night? Keep enough for you and export the rest.

Thank you for your insight

 

[binky]

Hello

I would like to share with you some thoughts and that you let me know what you think and what else I should consider.

The set: PV System 15kW. For simplicity let's assume 5kW facing East, 5kW facing South and 5kW facing West.
DNO does not authorize additional power to the grid and therefore 3.68kW is the only authorized power to be exported and the inverter will limit the export accordingly


Size the battery to store all the excess power which has not been consumed by the house (including heating hot water) and cannot be exported due to the limitation.
Then later when the panels no longer produce enough power and the house has enough power from the battery, the excess stored in the battery will slowly be exported to the grid (respecting the limit).

In other words, does it make sense with such an export limit and large system to send some of the electricity stored in the battery to the grid at night? Keep enough for you and export the rest.

Thank you for your insight

The battery releases leccy to meet demand within the house - no demand, no leccy release. Too much demand and you will use leccy from batteries and the grid.

 

[Bob Smith]

so let's say I have 15kWh in batteries at 9pm and I know I will only use 5kWh for the house during the night. You are saying that I will not be able to send to the grid 8kWh ? (I do not want to drain the battery )

 

[binky]

so let's say I have 15kWh in batteries at 9pm and I know I will only use 5kWh for the house during the night. You are saying that I will not be able to send to the grid 8kWh ? (I do not want to drain the battery )

It can be done, but why would you?

 

[Bob Smith]

If you cannot export all the power available because of DNO limitation, you can then better control what you send that way., no ?

 

[binky]

If you cannot export all the power available because of DNO limitation, you can then better control what you send that way., no ?

Why would you want to export your stored energy rather than use it yourself?

 

[Bob Smith]

Why would you want to export your stored energy rather than use it yourself?

if I have too much that I cannot use myself

 

[binky]

You don't flatten the battery to do that, you export surplus solar, or are you thinking of getting a flexible rate like Octopus Go?

 

[MHarv]

Exporting in Winter will not happen, any PV solar output will be for your battery again all depending on your Tariff… normal tariff you’ll be foolish to export for a lower price than the more expensive import; even on Octopus Agile and Go.

On Octopus Go (have EV now asked for plus in T&C’s when you apply)
Your Export SEG with them is only 4.1p
You need a Smart Meter same for Agile Import and Agile Outgoing (Export)

Summer time is King on Octopus you can change tariff without penalty only after every 31 days …

If you have EV, Solar Pv, iBoost+ or other HW heater and Battery storage Octopus Go is a great tariff, hard to be beaten on average kWh consumption versus other tariffs out there especially if you have BEV

I can charge EV 30.57kWh ( 100miles input into the EQA) and Solax HV Batteries 11.6kWh in the Octopus Go time period of 4 hours 0030-0430 hrs.

To be on other Octopus tariffs with Agile it’s all numbers game if you can put the time and effort in

 

[Bob Smith]

Maybe I did not explain the problematic well enough.

I am trying to figure out if it is technically possible to send to the grid the power stored in the day in the battery at night.?

The "Why would you want to do that" or winter or not is not the question and I have never mentioned EV

Thank you

 

[binky]

Maybe I did not explain the problematic well enough.

I am trying to figure out if it is technically possible to send to the grid the power stored in the day in the battery at night.?

The "Why would you want to do that" or winter or not is not the question and I have never mentioned EV

Thank you

I'm sure it could be done, although I can't think of any battery settings to achieve that, but why would you want to empty the battery every night? Batteries have lifespans based on charge cycles, discharging it at night is just wasting battery life.

 

[MHarv]

You can But is NOT Cost Effective versus SEG at to days costs unless have early FIT

 

[Bob Smith]

As explained in my initial post

1) It is not to empty the battery.
"so let's say I have 15kWh in batteries at 9pm and I know I will only use 5kWh for the house during the night. You are saying that I will not be able to send to the grid 8kWh ? (I do not want to drain the battery )"

2) The situation I may find myself is to have an oversized array and DNO will limit my export. Therefore if I cannot export my excess of electricity I need to store it but then if I have too much leccy stored will come a point where the batteries are full, the house has enough, I can't export more because of the limitation so the electricity will be "wasted" (surely not produced because of some security settings.

Therefore, if I could then send within the DNO's limit some of the electricity at night,

I hope this clarifies

 

[MHarv]

Maybe I did not explain the problematic well enough.

I am trying to figure out if it is technically possible to send to the grid the power stored in the day in the battery at night.?

The "Why would you want to do that" or winter or not is not the question and I have never mentioned EV

Thank you

My Tariff is TOU as example Why would I send stored energy back at SEG @ 4.1p

My TOU tariff is for EV plus Battery system
None better out there at present.
It all depends on different variables tariff, Import price, have SEG for Export on which tariff, which Energy Provider.

You did not say what tariff you are on or hope to be on in the future to make a case; study for consideration

 

[MHarv]

Hello

I would like to share with you some thoughts and that you let me know what you think and what else I should consider.

The set: PV System 15kW. For simplicity let's assume 5kW facing East, 5kW facing South and 5kW facing West.
DNO does not authorize additional power to the grid and therefore 3.68kW is the only authorized power to be exported and the inverter will limit the export accordingly


Size the battery to store all the excess power which has not been consumed by the house (including heating hot water) and cannot be exported due to the limitation.
Then later when the panels no longer produce enough power and the house has enough power from the battery, the excess stored in the battery will slowly be exported to the grid (respecting the limit).

In other words, does it make sense with such an export limit and large system to send some of the electricity stored in the battery to the grid at night? Keep enough for you and export the rest.

Thank you for your insight

“DNO does not authorize additional power to the grid and therefore 3.68kW is the only authorized power to be exported and the inverter will limit the export accordingly”

DNO’s will grant above >3.68kWh you just need to apply which is Full G99

What system have you got?

Or are the questions all Hypothetical to gather insight information

 

[binky]

Therefore, if I could then send within the DNO's limit some of the electricity at night,

I hope this clarifies

Nope .

You don't send anything back to the grid at night because you can't guarantee weather good enough the following day to refill the battery. If you find the battery is full and the solar panels are generating more than you need the inverter will export to the grid. If that export is greater than 16amps, the inverter makes itself less efficient to reduce power from the array, and sometimes even shuts down a string. There's absolutely nothing to worry about.

 

[Bob Smith]

This is hypothetical as I am in the process of designing my new system. I already have 4kWp on FiT and expect to add 10.5kW more but on 3 different orientations.

In the event DNO does not grant me enough or I do not want to pay the fee for extra power, the I am wondering what I'll do with that extra electricity.
Therefore, I thought, I could store it and when my panels stop generating above the DNO limit to then send from the battery what was stored which could not be send earlier because of the DNO limit.

 

[Bob Smith]

Nope .

You don't send anything back to the grid at night because you can't guarantee weather good enough the following day to refill the battery. If you find the battery is full and the solar panels are generating more than you need the inverter will export to the grid. If that export is greater than 16amps, the inverter makes itself less efficient to reduce power from the array, and sometimes even shuts down a string. There's absolutely nothing to worry about.

I agree with your point and I have my weather forecast app
So when you say the inverter shuts down. This is exactly my point when that happens you are wasting what the panels is generating. Thus me thinking how to store it and then later send it to the grid. This is anyway leccy I would have not being to use.

 

[binky]

I agree with your point and I have my weather forecast app
So when you say the inverter shuts down. This is exactly my point when that happens you are wasting what the panels is generating. Thus me thinking how to store it and then later send it to the grid. This is anyway leccy I would have not being to use.

If it shuts down, which it won't because it will still export 3.6kw, then you don't need the leccy. What the heck do you get from sending leccy to the grid that you have stored? You store it so you can use it yourself in the evening/ overnight when the panels are doing nothing. That's how you get the maximum benefit from paying out £thousands for batteries. Self use is the name of the game.

 

[Bob Smith]

I understand, the hypothesis is if I do have too much electricity.. but you know maybe I am overthinking it. I have more pressing matters. HV or LV batteries


Maybe best if an admin deletes this useless thread. Sorry for having started it and wasted your precious time......