Comment by robomartin | Hacker News Reader

Comment by robomartin | Hacker News Reader

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> All of those analogies apply to selling power back to PG&E at retail prices. It's in small lots; it's undependable; it comes from many sources, not just a few; and it's priced wrongly.

You must not be an electrical engineer.

Do you think the power I generate from my solar array travels a hundred miles to some facility to then be sent back to the house next door?

Not so.

Multiple homes are connected to, and fed by, power distribution transformers. In other words, five to ten homes share the same output. Which means that excess power from one or more of those homes is fed directly to any home that needs it.

My power goes directly into my neighbor's meter. The power company charges my neighbor the full rate for my power. They pay me almost nothing. Pure fucking profit.

Of course, it would not be sensible to ask for the full rate. However, they should pay a good percentage of what they are charging for the power. Among other things, if anything breaks it is my responsibility to fix it. And, of course, I paid for the entire system. They sell my electricity at full rate with minimal costs.

Maybe a silly question, but from those of us that aren't electrical engineers.

Am I correct in assuming that excess generated power can't leave my local distribution network? So there are X houses in my circuit served by a dist transformer, and if we can produce more than those X houses need at that point in time, then the excess simply doesn't get "pulled" from the panels?

It's a good question.

Theory: Transformers are bidirectional. You can drive them from either side.

For example, in testing one of the devices we manufacture we need 480 Volts AC. At each test rig we use a 480 V to 220 V transformer, drive it backwards and generate 480 VAC from 220 VAC.

Distribution transformers have primaries in the tens of thousands of volts (say, 50 kV) and 220 VAC (for residential service) outputs. The topology could be different, however each home receives a two leg service with 120 VAC per leg.

So, yes, you should be able to drive the low voltage side and end-up with high voltage on the other side.

Let's say you have ten homes on the same transformer. Each home has solar. During a holiday, all homes are empty and nearly all of the power they generate drives the transformer backwards. The power would then drive other transformers and feed homes that need it.

What I don't know is if they explicitly have devices to prevent backwards flow of power. I don't think they do. Not sure this would make any sense. I could see protection devices to prevent overload.

You must not know much about actual PG&E equipment.

A neighbor here told me there was a 6-month wait to get solar & its associated metering, because PG&E doesn't have the equipment on our lines that can accept power back from the customers.

Sending humans out to fix things is costly.

You use local distribution when selling power back, but your point still stands it is mostly profit.

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