07-01-2015, 05:12 AM
The power that is produced by rooftop solar is not of the same quality that HELCO produces. If you cut the connection to the panel-mounted inverters, they stop producing power. They need to "see" the grid's power wave so they know what to do. Another facet of this is that as the ratio of solar power to grid power goes up the system becomes less stable since it is the grid power that is defining the sine wave of the system. Imagine a truck towing a trailer. Big truck with a small trailer, truck hardly knows the trailer is there. That's how it used to be. As the trailer approaches the weight of the truck maintaining stability becomes a real factor. There must be a practical limit. A ford F250 weighs about 6,000 lbs and can tow under ideal conditions 15,000 lbs, a ratio of about 2 1/2 to 1.
I was speaking with a HELCO shift supervisor the other day. Factoring in existing grid tied solar and applications for new solar connections that HELCO will have to accommodate, there is something like 90 mw of potential unstable solar out there that might flood their system on a clear sunny day. Traditionally, the peak load for the whole Big Island on any given day is in the mid 90's of mws. So back to the truck/trailer analogy. That 6,000 lb truck that can only keep 15,000 lb of trailer under control will soon be expected to successfully steer 90,000 lb of trailer.
If you were in HELCO's place you wouldn't want to pay people to do this to you either.
I was speaking with a HELCO shift supervisor the other day. Factoring in existing grid tied solar and applications for new solar connections that HELCO will have to accommodate, there is something like 90 mw of potential unstable solar out there that might flood their system on a clear sunny day. Traditionally, the peak load for the whole Big Island on any given day is in the mid 90's of mws. So back to the truck/trailer analogy. That 6,000 lb truck that can only keep 15,000 lb of trailer under control will soon be expected to successfully steer 90,000 lb of trailer.
If you were in HELCO's place you wouldn't want to pay people to do this to you either.