Feb 162014
 

PG&E Report

For the first full month of solar our PG&E graph goes a little wonky:

Technically speaking, Jan 15-Jan 20 was the first part of this last billing cycle, but despite that, our PG&E contract was still on the old pre-Net Energy Metering (NEM or Solar) program.  Which meant that PG&E was not tracking energy credits when I over produced.  I mentioned this in a previous article about how they had to download new software to our meter– Well, Jan 20th was the date they did that so Jan 21 was the fist date we were on the NEM program (and actually tracking credits.)

However, Jan 1-15 was part of the Dec 15-Jan 15 billing cycle and apparently PG&E decided to roll the charges from Jan 1-15 onto the December part of the graph.

It’s so weird how they handle the numbers.

Looking at the post-NEM period (Jan 21-Feb 12) we did pretty good on energy production vs consumption. We produced 291 kWh according to our monitoring service, we consumed 372 kWh beyond production (meaning that we consumed 661 kWh for this 23 day period. So, all in all I’d say our usage is also down from normal.  If we extend that consumption average out over a 31 day cycle we’d arrive at 890 kWh for 31 days (estimated).  The difference is likely my personal PC being in the shop between Jan 13 and Feb 5.)

PG&E Invoice, Plan Conversion, Total charges

Because our energy plan changed on Jan 20, we do pay for the electricity usage on the old plan between the 15th (when the paperwork for the plan conversion was filed by PG&E, not when we filed the paperwork with PG&E) and the 20th when the conversion was actually completed. But, between Jan 21 and Feb 12 (this first cycle) we only pay the “NEM minimum energy charges”, which for us is only $3.40 for Jan-Feb.

The balance of the charges for usage accrued is now “on account.” If we produce more energy than we consume during the coming summer months, then our credits will be deducted from the annual usage.

Once a year we’ll have a “true up” invoice which will be significantly larger than our monthly bill, but will be the total of all charges for the entire year.  This does require a little more planning and budget control, but our electricity being cut significantly means that our annual invoice will be significantly lower than our annual sum of monthly charges would be without the solar.  (e.g., Let’s say $300 per month in electricity over 12 months is $3600 annual electricity  charges.  If we say that the solar panels eliminate 80% of that bill, then the annual charge post-solar is $720.  ($3600 times 20% is $720.) This is a lot higher than a $300 monthly bill pre-solar, but when you compare $3600 to $720, it’s a lot less over the entire year.  These numbers are completely fictional to my scenario.  Until I have a full years worth of history it’s impossible to do anything other than forecast poorly.)

Our true up period for electricity seems to be Jan 15, 2015 (and annually thereafter). There is a detailed NEM energy charge summary for this billing period, which shows Tier 1-3 usage and taxes.

Some of the wording on the invoice is questionable and will require further investigation:

 If your total cumulative energy  charges are negative at the end of the true up period, the energy credit is zeroed out and not carried over to your next true up period. If your total net usage is negative at the end of your true up period, you may qualify for Net Surplus Compensation that will be reflected in your true up bill.

According to the video on the Net Surplus Compensation page, if you have a credit on your account it will be converted to a cash credit (at wholesale rates) which can be rolled over into the following true up period.

This seems to contradict what I was told when I was “sold” the system (that credits could be rolled over from one period to the next. This would be critical if your true up period began during the summer months when your energy production, and therefore credits, were at their peak. This is less critical to me as Jan is likely to be a month when we are consuming more power than we produce. Still, something that I need to look into and will follow up in a future article.)

Edit: Upon further reflection, after a full year of production and consumption peaks, this is not as big a deal as I thought it might be. Regardless of when during the year your period begins, you will have the same peak usage and peak energy generation. (e.g., winters being peak usage due to short days and less sun, summers being peak generation due to long days.)

Unsurprisingly, PG&E even tells you that there is no incentive to build a solar system large than you can use (after all, the problem isn’t transmission, but storage. Producing 5 MWh more power than we consume does nothing for anyone. The energy “goes nowhere.”– technically it goes somewhere, but I don’t know enough about the grid to speculate where surplus energy goes. However, it is safe to say that it goes nowhere useful.)

What if I install a larger generator than my home needs?

There is no incentive for installing a system larger than your business needs. Compensation for excess generation through Net Surplus Compensation is set by the California Public Utilities Commission at a wholesale rate that does not justify the cost of an oversized system.

Now, this is just the electricity portion of the bill. I also have gas, and the gas portion of the bill is invoiced monthly, just like normal.

TCO of my personal computer (a side note)

On a side note, I bought a Belkin Energy Use Monitor

and my 1500W personal rig seems to consume approximately 300 kWh per month (which is about right when you look at the reduced energy charges for this period.)  When you work this out as a monthly dollar amount it comes to about $25 bucks a month (but can double if I get myself into higher tier rates for electricity.)

Jan-Feb Solar Energy Production

Now, if I’d been thinking about how I wanted to write this post back in Jan/Feb, I’d have snagged some scrapes of  the forecast– but early February my area got hit with a nice deluge of cloud cover and rain. The Sonoma area (about 73 miles or 90 minutes North of me) actually posted flood alerts in the last 14 days, but we just got excessive cloud cover. What do this mean you ask? (Maybe you didn’t, but I’m monologueing here.)

During the height of the rain/cloud period energy production never exceeded 7.5 kWh for the entire day.  In early-mid January and clear skies, production reached nearly 17.5 kWh.  As we get closer to summer (better angle between the panels and the sun, more panels exposed, etc.) even with moderate cloud cover we managed to get up to 15 kWh for a day.

Today (so far) is looking to be clear and sunny all day (despite the forecast predicting clouds)

As of 9 AM this morning, energy production was already in excess of 1 kW/h (our “break even” is somewhere around 880 Wh or .88 kWh). By 10 AM energy production had exceeded 2 kW/h. Peak production has been around 12:30 PM.

Today (as of 3:20 PM)

18.8kWh
Peak Power: 3.36kW at  1:50 PM

I can’t express how exciting this is.

(Unfortunately, from time to time, the microinverters experience enough line noise that they stop reporting how much power they are generating– they’re still generating power– but due to the noise we lose the granular detail. Instead it tracks total reporting intervals missed, and total power produced, and then displays the average for the entire period of missed power. A straight line instead of a up/down slope. Line noise can be caused by anything, including stuff going on in other houses on the same grid. In our case, I cannot find anything inside the house that is causing the problem so I suspect the problem is in a nearby house on the local grid.)