1 hour ago, lom said:

No, you will not infringe on transformer capacity. What you feed in before the transformer will be used before the transformer by the other customers under the same transformer.

That also means that there will be less need of energy for the transformer to transform and if there are enough solar plants within the transformers distribution area then these plants could feed all non-solar customers so that the transformer would be idling.

Sorry, not following you. PEA doesn't limit the solar power sent to a transformer? I was told they do but never confirmed. Who told you PEA doesn't limit solar in an area? Below is my post you responded to.

3. The Local Feeder Bottleneck

This is the hidden trap that trips up homeowners who try to expand later. PEA limits how much solar power can be fed back into any single local transformer district to prevent grid instability. If you try to upgrade your system size a year or two down the line, you might find that your neighbors have taken up the remaining transformer capacity. PEA can—and will—reject your expansion request simply because the local grid can no longer accept the extra power.

As far as I can see, the specs of the 2026 rooftop solar purchasing program is similar to the latest 2024 program for which I have a contract.

In 2021 built my DIY grid solar connected to an analog PEA meter. Those were happy days, as long as you don't export more than you consume at the end of the month. While on holidays Jan 24 I forgot to switch off export. PEA changed the meter to digital. End of happy days. This period gave me the best ROI.

July 2024 met a PEA engineer who installs solar as a side job. He helped me with issuing the technical diagrams and collected the specs of panels and inverter. My DIY install needed no changes. In Nov got the green light for inspection. He made drone pics of the roof. Inspection was done by PEA Phetchaburi. Lasted 1 hour. Only inverter and combiner box were checked. Turn export on/off. No physical checks of panels, cables or grounding rod.

Collecting the money is also interesting. For every month with a credit amount, my wife has to sign a paper in twofold prepared by a PEA officer. The money need to be collected at the PEA office. Fortunately we can collect once a year.

4 minutes ago, 4myr said:

As far as I can see, the specs of the 2026 rooftop solar purchasing program is similar to the latest 2024 program for which I have a contract.

many thanks for your post!

how does the 5 kw PEA export limit work? do you have to set an export limit in your string inverter, or does the PEA enforce it through the smart meter?

4 minutes ago, motdaeng said:

many thanks for your post!

how does the 5 kw PEA export limit work? do you have to set an export limit in your string inverter, or does the PEA enforce it through the smart meter?

I can only confirm what was tested at inspection. No limit needed to be enforced in the export of inverter. I oversize my panels but clipped by the inverter. I think as long as your inverter has 5 kw specs and on the approved list it is OK.

I don't know if the bidirectional meter clips the export. I export less than what the inverter produces.

28 minutes ago, atpeace said:

the local grid can no longer accept the extra power.

There is no extra power. If the area draws 100KW from a transformer and you feed the area with 5KW then those 5KW will be consumed in the area and the power through the transformer will decrease to 95KW.

1 hour ago, lom said:

No, you will not infringe on transformer capacity. What you feed in before the transformer will be used before the transformer by the other customers under the same transformer.

That also means that there will be less need of energy for the transformer to transform and if there are enough solar plants within the transformers distribution area then these plants could feed all non-solar customers so that the transformer would be idling.

That statement is too absolute. Whether transformer capacity is affected depends on the balance between local generation and local load.

Solar penetration changes the grid from a one-way street to a two-way street. Without careful capacity management, distributed solar can overload transformers (lower risk), lift voltages to unacceptable levels (higher risk), and compromise reliable grid operation.

16 minutes ago, Fruit Trader said:

Whether transformer capacity is affected depends on the balance between local generation and local load.

In an area with 100 consumers the transformer should have at least a rating of 500KW since a 5KW meter is the smallest PEA provides.

Now if every Peter, Paul, and Mary in the area has a solar system that exports 5KW then there are no user consuming grid power and 500KW will flow in the other direction and the transformer still operates within its limits.

There is a reason why the export is limited to the same amount (5) of power as the common single-phase meter..

Edited July 7Jul 7 by lom

24 minutes ago, lom said:

In an area with 100 consumers the transformer should have at least a rating of 500KW since a 5KW meter is the smallest PEA provides.

Utilities design grids based on diversity factor. 100 homes at 5kW will not get a 500kW transformer.

If a simple math equation is preferred then use realistic ratings. Far better view it as a dynamic network with physical constraints.

Edited July 7Jul 7 by Fruit Trader

1 hour ago, Fruit Trader said:

That statement is too absolute. Whether transformer capacity is affected depends on the balance between local generation and local load.

Solar penetration changes the grid from a one-way street to a two-way street. Without careful capacity management, distributed solar can overload transformers (lower risk), lift voltages to unacceptable levels (higher risk), and compromise reliable grid operation.

I agree with you but my post was about the limits PEA places on solar and had nothing to do with transformer capacity. It is not an if type of scenario. If the amount of solar is met for a district they will not allow more. Submit an application and if the solar quota is met prior then Denial 100%.

PEA does not want solar because it erodes their cash flow. Higher up government officials know this and are struggling with how to get PEA to play nice. Not an easy task because of the incentive structure. Change the incentives though and PEA would change their stance.

Maybe my post was unclear but that was the intent :)

Edited July 7Jul 7 by atpeace

15 hours ago, lom said:

No, you will not infringe on transformer capacity. What you feed in before the transformer will be used before the transformer by the other customers under the same transformer.

That also means that there will be less need of energy for the transformer to transform and if there are enough solar plants within the transformers distribution area then these plants could feed all non-solar customers so that the transformer would be idling.

I have 22kw in panels and 18Kw in single phase grid-tied inverter.

I could output about 6Kw most of the time but rarely anywhere near 18Kw as the voltage climbs too high and they “error”.

We don’t export anymore since we got caught, punishment was just being told we’re naughty.

14 hours ago, atpeace said:

I agree with you but my post was about the limits PEA places on solar and had nothing to do with transformer capacity. It is not an if type of scenario. If the amount of solar is met for a district they will not allow more. Submit an application and if the solar quota is met prior then Denial 100%.

PEA does not want solar because it erodes their cash flow. Higher up government officials know this and are struggling with how to get PEA to play nice. Not an easy task because of the incentive structure. Change the incentives though and PEA would change their stance.

Maybe my post was unclear but that was the intent :)

I had no problem understanding your post and was not replying to its content directly. What followed was my argument.

PEA a government owned utility has financial and operational reasons to be cautious about widespread rooftop solar because it can reduce electricity sales while leaving most grid maintenance costs unchanged. However, we cant deny that PEA has also supported rooftop solar under government policy so it is not accurate to say it simply does not want solar.

... it looks like not everyone is happy with the solar roof scheme 2026 ...