Solar Panels – DNO, Zero Export and Regulations

Reed_Richards

It used to be said that when a popular TV show was over there was a spike in electricity demand as many people who had been watching TV then put the kettle on.  I wonder how the number of people with solar panels compares with the number of thirsty TV watchers?  Can the DNO perceive a sunny day because of a drop in the normal level of demand around the middle of the day?  

[Deleted User]

QrizB said:

My supplier? My supplier does nothing in particular with it, since I'm receiving FIT payments. They simply take my meter readings, do a bit of admin then pass on the payment from the Government.

In return, I'd quite like you to explain exactly how foregoing SEG payments (by using a zero export setting on your inverter) is going to be more cost-effective than taking your suppliers money for surplus power would be.

There seems to be a moral dilemma: you are a generator and your export has nothing to do with the wholesale price of gas now or in the future. Indeed, your export has cost your supplier nothing because the taxpayer paid you for what was exported. May I suggest that your supplier takes your export and sells it on and come October this will be at around £0.43/kWh. SEG or FIT you will be importing electricity during the night and at this rate too. How do you feel about this as a generator?

Despite the controversy above, SEG and FIT are good 1 phase schemes with no power wastage however they are not scaleable because of prospective problems with DNO infrastructure. So why would you want to change to zero-export it makes no sense.

Zero-export on the other hand attracts no controversy and costs the taxpayer nothing what's more DNO infrastructure is not affected which makes it highly scaleable by the millions. Generated power is self consumed but there can be wastage something that can be addressed if the excess power is available in a suitable form that the consumer can use.

[Deleted User]

Reed_Richards said:

It used to be said that when a popular TV show was over there was a spike in electricity demand as many people who had been watching TV then put the kettle on.  I wonder how the number of people with solar panels compares with the number of thirsty TV watchers?  Can the DNO perceive a sunny day because of a drop in the normal level of demand around the middle of the day?  

This is not a DNO issue so much, however shock loads can trip sub stations. Managing network loading is down to National Grid who do an absolutely amazing job of keeping our Gas and Electricity available to us.

QrizB

[Deleted User] said:

There seems to be a moral dilemma:

Not to me.

How do you feel about this as a generator?

I feel nothing in particular. I entered into an agreement with the Government whereby I paid to install sonar panels, and they agreed to pay me at a set rate for the next 25 years. I kept my end of the deal and they are keeping theirs.

Now I'm out of this thread, since you seem to have no interest in explaining the glaring anomaly in your proposal:

I'd quite like you to explain exactly how foregoing SEG payments (by using a zero export setting on your inverter) is going to be more cost-effective than taking your suppliers money for surplus power would be.

ispookie666

Most of the inverter manufacturers would have type tester their equipment so that it will comply with G98, G99  and at times g100. Most of the time the G100, export limitation is done by using various grid profiles (Enphase and Victron).  These certifications are available on the manufacturers site and the central repository. 
I do not see what is incorrect in what MCS have said - their members are installing the panels and the inverter manufacturer has obtained required certification. At times the DNO might want to check the export limitations on site. 

Exporting power to the grid might help my service provider (SEG/FiT) add to this lower transmission losses. I'm yet to see a street where every house is full off solar panels ☺️. 

[Deleted User]

ispookie666 said:

I do not see what is incorrect in what MCS have said - their members are installing the panels and the inverter manufacturer has obtained required certification. At times the DNO might want to check the export limitations on site. 

Exporting power to the grid might help my service provider (SEG/FiT) add to this lower transmission losses. I'm yet to see a street where every house is full off solar panels ☺️.

Like I said previously the panels themselves do not connect directly to the DNO infrastructure the issue is one for the panel manufacturer. They want a competent install of their their panels which MCS provides if their their guarantee is to be protected.

Zero-export is different because it is so highly scaleable second hand panels may be used in a way that does not happen with SEG/FIT as these are usually lots of new panels to maximise output with a need to last for decades.

In parts of the world like the US, Philippines and Hawaii export to a pole transformer would damage it leaving the DNO with costly repairs so they do NOT allow exports to grid. You will however see streets full of zero-export installs and with panels of dubious origin but nevertheless affordable even in the poorest of neighbourhoods.

You are quite right about inverter certification. It is the inverter that protects DNO infrastructure wherever they are installed in the world not the panels themselves. As solar power matures more and more used panels become available and at an affordable cost. The requirement is not to export as much power as possible to maximise earnings it is quite simply to provide power for self consumption with power to spare. The needs of SEG/FIT and zero-export are quite different in these respects.

ispookie666

Not sure what you are trying to imply? 
Solar panel age does not matter in installation so your whole argument is moot. 
I fail to understand if your issue is 
1. DNO 
2. Power supply company 
3. MCS 
4. Other - cannot accept properties which have G98/G99 installation and is not applicable in your case 

Good luck, I'm out 

[Deleted User]

This thread lost all credibility when the OP suggested that he could get a return of 10% interest on £6500 in a bank/savings account.

[Deleted User]

Dolor said:

This thread lost all credibility when the OP suggested that he could get a return of 10% interest on £6500 in a bank/savings account.

As this post is drawing to a close and by popular demand.

Design: Zero-export must reduce import cost by 1 kWh per day where 1 kWh = 0.43 and wastage of available power is 50%: two Sunpower Maxeon 400W panels are in use.

What interest rate would earn £0.43 per day in the bank?

Formulae: P x % = K x 365

% = Simple Interest Rate. K = Price per kWh. P = Savings Amount

% = 0.43 x 365 / 1500 = 10.46%

What interest rate would earn £0.28 per day in the bank?

% = 0.28 x 365 / 1500 = 6.8%

How much will bank savings of £1500 at 2.5% earn per day?

1500 x 0.025 / 365 = 0.1027 per day

Costs are being reduced in a solar year of 6 months by:

(0.43 - 0.1027) x 365 / 2 = 59.73 (equivalent savings interest of 3.98%)

(0.28 - 0.1027) x 365 / 2 = 32.35 (equivalent savings interest of 2.16%)

Conclusion: the install cost of 1500 is earning more than it would do in the bank. Real world testing and changes to lifestyle to reduce or accommodate wastage is seeing 3 to 5kWh cost reduction per day and over the solar year a 50% reduction in import costs. In any regard yearly standing charges for gas and electricity is being fully recovered.

theoldmiser

[Deleted User] said:

The burning issue is the amount of export or excess power that has to be got rid of. Some devices sense this and divert to hot water heating with batteries being a very expensive alternative.

All solar inverters use MPPT (Maximum Power Point Tracking) to extract the maximum available power from a solar panel string, but they also use this to only take as much power from the solar panels as the load requires - the 'load' being your house's electricity usage at that point in time, and/or your batteries' charging requirements at that time, and if export capable inverters, then also the amount that your DNO allows you to export. That's all.

So there is NEVER any "excess power that has to be got rid of". MPPT simply doesn't work like that - it controls what it takes from the solar panels at all times.

Even QrizB didn't notice that part... LOL. And he seemed reluctant to explain what his supplier did with the electricity that he exports - LOL again. He says "My supplier does nothing in particular with it." Of course they do something with it - you can't just export electricity back to the grid and it ceases to exist, and this is the whole reason why, if you are planning to export electricity back to the grid from your solar panels, you need to inform your DNO so that they can see how many other people in your street are already exporting, and they can decide whether their system can cope with any more electricity being exported, and if so, how much they will allow you to export.

Personally I have 'off grid' inverters (not capable of export) so I don't have to worry about this. I'll wait a few years and see if Octopus are still offering 15p/kWh then, before going down the export route.