OK, once again, I'm not from California, but I'd appreciate a bit further explanation about this.
I understand that ttweed ended up using 600kwh over the year, so he is a NET consumer of power. I understand what has been said that much more power could have been used without any financial impact to ttweed.
So the credit of ttweed's kwh (@ $0.04/kwh) sent to the grid went to offset the minimum $120/year charge. I think I'm understanding that.
In California, we have the choice of time of use or tiered billing (for the Investor owned utilities anyways). If you are on TOU, then the utility tracks both the retail dollar amount of NET generation plus the energy usage amount. The only time you will receive the ~.04/kWh generation credit is if you are a NET producer over the true up period. The retail amount that is tracked can only be used against energy purchases in the same true up period - if you have a credit at true up, you lose it.
sub3marathonman wrote:So why didn't ttweed get any further credit or payment for the other $550 of electricity (even @ $0.04/kwh) that was sent back? If the power company didn't get it from him, they would have had to purchase it somewhere else.
This is correct - he produced it and was not compensated for it in any way. So he could of had a smaller PV system and lowered his capital expense.
sub3marathonman wrote:And what would have happened if ttweed used 700kwh less, and was not a NET consumer of power?
He would get a generation credit for the 97 kWh he over produced - ~$4.00
sub3marathonman wrote:I will say, from my perspective, that the power company has a sweet deal there in this situation, as there was no usage at all during peak times, and the PV sent huge amounts, 2.5MW, of power back to the grid at the most critical times. Here in Florida, it is always being stated that PV customers are somehow taking advantage of the power company because the sun doesn't shine at night, but in my opinion it only matters if the sun is shining during peak periods, where by definition somebody with PV generation will use less, or even send back to the grid, as opposed to another customer who runs his dryer, A/C, and arc-welder during peak times because TOU rates are not the norm.
It is more complicated than that and depends on the time of the year.
In California, PV has pushed the peak into the afternoon/evenings. A lot of this has to do with utility-scale solar farms and lesser to residential rooftop PV. In fact, the grid-scale farms have to curtail production during the middle of the day at this time of the year due to over-production/low demand - yet at the same time residential NET metering customers are "selling" this power to the grid at peak rates. Residential installs do not have the capability to curtail production, so the utility "must take" the power generated from NET metering customers.
FWIW, the California IOUs have or are in the process of changing the peak times to the afternoon/evenings.
You can look at the current demand on the CA ISO page. If you scroll down to the NET demand chart, the green line shows what the traditional power plants are providing - look at the big dip in the chart in the middle of the day (for this time of year) - a lot of traditional plants have to go idle, which raises their net operating cost. Residential PV is "behind the meter" so it shows up as reduced demand on these charts. The solar shown is the utility scale plants.