National grid transformer won’t support additional solar

That can and does happen. I was lucky and am the only person on a 50 kva transformer, so I didn't have to pay for the upgrade. I believe others in this group have posted, and it usually ends up being a couple grand. The utilities are usually sizing for ac inverter capacity, so when getting your interconnect approved this is your chance to get your sizing, or really any increases in the future approved. If you are going to be shelling out a couple of grand to fund a transfer upgrade, make sure you get what you will need in the future... don't want to have to go back to the well again in a few years.

Fair, right or equitable or not, that doesn't sound that unusual, and may be becoming more common.

When I lived in Albuquerque, new A/C installs were being allocated in my part of town pending service upgrades.

Seems that many homes had been cooled by evap. cooling (swamp coolers) and the move over to A/C which increased demand by maybe 3-8 kW/household on hot days was putting a strain on local distribution in various parts of the POCO's service area. Customers in affected areas were not asked to foot the bill for specific improvements in the electrical grid, but surcharges were applied to specific areas based on increased demand and there was some talk by the POCO of instituting demand charges for residential customers.

I moved back to San Diego before there was any resolution to the situation or if there was one, what form it may have taken, but being NM and all, my guess is it's still a cluster function.

What did you POCO tell you when you went to the horse's mouth and enquired ?

Sounds like the utility doesn't understand that solar actually feeds power back into the grid and helps to power the neighborhood. I could see the transformer being too small to support a bunch of EVs in the neighborhood. Unless there is already a bunch of solar on your street, the utility is just making this up to deny the solar permit.

There are about 50-55 houses on our circle and lots (maybe half) of them do currently have solar installed. Most went with the 8.6 kw to 10kw size system. so, I guess it’s conceivable we ran out of capacity on the transformer on high production summer days.

In the US, many states have special solar regulations that require the utility to accept small solar installations under a set limit (usually 10 KW). In that case the utility has to upgrade the system at their cost to accept the load. This is definitely very jurisdiction limited. Time to talk to your local legislator to get the rules changed as the push is on to get more and more solar on the grid.

The bigger transformer is needed to provide power when the sun isn't shining so you should not include the kw that a solar install provides. The POCO is tasked with keeping the lights on at night and during inclement weather so additional loads (like and EV) may require a bigger transformer. Something that most people do not understand that the grid was originally designed to handle a specific "load" and with people now adding to that load with EV's the old formula and grid configuration is out of date and will need upgrades. That may be either or both bigger transformers and wire.

If that were true then they wouldn’t have a problem issuing a solar installation permit. They don’t have a problem building the house with the additional load they have a permit for that already. They have a problem issuing a permit for solar which takes the load off the transformer. The are asking for information about how many ev are present on the circle as an excuse to upgrade the transformer to get around the expense. So it’s explained as a solar generation problem not a draw loading problem as I understand it.

Again most people are uninformed that solar will reduce the load on the grid. That may be true for as much as 40% of the day but not for 100%. Also the grid was designed for sending power one way not 2 ways and the infrastructure may suffer from that type of distribution. A solar home is not always continuous and the sudden on / off of sending power can cause the POCO to have issues.

All those people that really think they are helping the POCO with a solar installation are incorrect in their thinking.

That is kinda self explanatory since the sun isn’t overhead 100 % of the time. I’m pretty sure most people are informed about that. Solar by definition will relieve the grid since the power generated goes into the houses closest connections. I don’t see how transforming (step up vs step down) makes the grid suffer?

producing power and not loosing through long transmissions lines is better for everyone. Have you seen the power transmission costs and losses lately?

again the home owner can build his house and install as many ev charges as he wants. He just cannot install solar panels. You need to explain your views more clearly so everyone can understand your point of view.

Physics tells us that transformers are bidirectional. What specifically can get damaged from an infrastructure standpoint from power flowing in two directions? Please consider how the power flows to the closest other loads on the same transformer first then onto the distribution network where it most likely serves the loads down stream of a substation which actually reduces the load at a substation.

What solar systems have you seen that "suddenly" stop sending power? My systems gradually taper off on cloudy days.. Turning off my oven or electric dryer is more of a shock to my system than my solar system will ever produce. with Megawatts of power on the grid. Please explain the physics of the shock to the system if I were to turn off my breaker when I was generating 6kW of back feed or running my dryer and oven when I shut off the power? Solar eclipse? Even that concern was debunked years ago.
I realize as a moderator you make the rules, but I live in a world where facts and the laws of physics are important and would like to hear the facts that support your opinion. A simple Google search on distributed generation would suggest there are other opinions that may not be incorrect in their thinking that distributed generation helps the grid and may be more efficient.

Solar eclipse are not necessary. There are these things called clouds. You can produce 70 kw or you can produce 3 kw depending on conditions. You have seen snow coving solar panels before where the produce absolutely nothing? You produce or you consume? The average daily usage for a home depending on size and weather conditions is 30 kw. You can produce enough power to support your power usage or you cannot. Even you have to admit the excess power you produce isn’t going to Canada. It most likely going to the houses surroundings where it’s produced. It’s going back onto the grid locally. Obviously, electric devices are needed to achieve this otherwise solar wouldn’t exist.

30 kW on average would be 720 kWh per day. That seems like an exaggeration or did you confuse kW with Kwh? My average per day is less than 30kWh with electric heat in winter. Your point about solar production going to my neighbors homes is consistent with my point that distributed generation does not hurt the grid.

You mention the average system is 10 kW but try to make the point about a 70kW system turning off when a cloud goes by? Consistency would make your argument more persuasive.
Have you Googled or researched distributed generation as a concept?

Maybe you are correct but again the POCO's own the grid and write the rules. We can either abide by them or go totally off grid and power our own needs and that won't happen soon because it is too expensive for the homeowner.

I know the grid is not designed for 2 way operation based on my past history as an EE. While it is easy to justify and believe the power is going to local loads you have to remember the electricity will go to the least resistance place instantly. So even if the loads may be local if there is more power being generated (more and more homes getting pv) then what is not used will go somewhere and that may be farther back up the grid to other loads.

That is the main reason Hawaii chose to limit new solar installations. Their grid was not designed for more local generation then what could be consumed. So they stopped granting new pv installations until they could upgrade the grid to handle 2 way flows.

I do not need physics to understand that people feel they are entitled to installing their own power source but they have to understand what they feel is their right is not always true.

Actually, it's engineering and not physics that made transformers bidirectional.Could you elaborate on some of the physics you claim or at least imply you know a lot about ? Begin by considering how power flows to and from all loadsin/out of a transformer as f(load imbedence), not distance and does so almost instanteneously or as modified by some capacitance or other circuit components

You're out of your depth and spreading useless crap as usual. You repaet what you read without understanding the whys and the science behind stuff. You're dangerous to the casual reader l

As for your inference that a moderator can be so petty as to be a bully - as if truth and real knowledge can be a function of the biggest stick, or that being in your world is different from everyone else's world where the laws of physics which you seem to know little about are apparently not as important as you think they ought to be is an idea that's patently childish and a cheap shot.
IMO only, crap like this makes you dangerous to the uniformed reader and a wart on the butt to everyone else.
Your spouting off and bloviating lowers the quality of this forum.