So many of the posters and proponents of alternate energy solutions seek to get off the grid which I am coming to think is a bad approach.
By connecting to a complex and smart grid could we not exchange our energy better? we generate when the wind blows or sun shines and consume when we don't. We use the grid to stabilize and offset consumtion. On hot and clear summer days the grid gets lots of added power from our little home solar systems and the hydro and steam powered generators can throttle down or in the case of some hydro, pump the water back up the hill with the surplus. I would think the socially responsible approach is to increase the grid ties rather than get off. The more producers makes the grid more reliable, but of course more dangerous too, as the power can come from many more sources.
Part of the issue is, are we talking about Transmission or Distribution grid ties?
Where are the most losses? How do we deal with large area variations when the sun goes behind clouds or the storm front blows through? How do you deal with islanding? What about remote generation tied into a remote spur that requires upsizing the spur? One of the issues with using a variable output power source is maintaining grid stability. Ramping up and down hydro is not a 5 second operation. Gas Turbines are 15 minutes to bring online. Coal and biomass may take 6-12 hours for large power shifts.
Grid stability may initially go down before it comes back up. Unfortunatly I don't not know of any quick responding, large capacity power absorbtion / storage / regeneration technologies that are commercially available and economically viable yet. Flywheel systems are beginning to address this but they are not wide spread yet.
How many substations are setup to take power From the distribution system and push it back into the transmission lines to be used somewhere else?
You bring up some good points Larry. Within my Twp we have modest resi systems dumping into the 120/240 secondaries, comm jobs, dumping 480, 3 phase into the secondaries of the respective pad mount xfrs, and I guess in theory...back to the primary (13.2/25 KV) distribution. One could also guess that it could be 'used' at a neighboring non-solar occupancy, or find it's way back to a sub station. That I will leave to those who have more theoretical brain cells then I.
The instability of the generation source as to weather related, time of day, season, maintenance, etc. are things that I have thought about, and debated with a few solar installers. No concensus was made, but opinions are plentiful.
One upcoming job is 4.26 MW in an industrial area. My opinion on that...the refrig whse will use a quantity, and some of the adjacent facilities will probably consume the balance.
If the ads are any clue, this mystical new "smart grid" technology will solve everything, although I'm not exactly clear on what said technology is and why it's so important if grid-tie systems worked just fine before. Sounds to me like just another buzz word for the naturally occurring evolution of generation, distribution and metering technology.
In theory, it sounds best to me to keep everyone tied together. While solar isn't going to keep the lights on at night, it can at least help with the peak usage during the daytime. Until cheap storage comes around, we'll probably be dealing with large base load generating stations for a very long time... At least until we have macro power grids of superconductive materials, so we can pull solar from the other side of the world :P
I think there will be some "fuel charge" savings to be had in these distributed energy systems but all of the fixed charges will end up being higher. You still need the capacity to supply the whole grid in a blizzard so the utility still needs the same plant. Having it sit idle may actually be more expensive than running it, from a maintenance standpoint, and you need the crew in there ready to pull the trigger at a moment's notice. In subtropical environments, big storms can come up with a moment's notice. It is certainly more convenient for the homeowner to shift the management of their excess power over to the utility instead of storing it on site but there ain't no free lunch.
Perhaps smaller generators, such as gas fuel cells like the "Bloom Box" will find their way into substations, to supplement what is already available in the neighborhood. That could take over for the solar/wind/etc. when it's not sunny or windy.
I'm not saying that centralized power plants should or will go away soon, but there are smaller-scale technologies that people will want to cash in on. There will always be a need for base-load generating, and I'm sure there are plenty of smart people who can figure out demand models for traditional generating stations and contingencies for when the weather doesn't pan out. It's not a change that is going to happen overnight. These small-scale things are probably not going to do serious damage to big power any time soon. It may be that, as time goes on and better technologies become available, the supplemental power is used to phase out dirtier tech like coal.
Ironically, the solar highway project I posted about a while ago had its first day of grid-tied generation when all of the panels were covered in snow. They even produce some power (around 500W) at night, although nowhere near the designed capacity of 104kW.