Gas station without pumps

2018 November 14

Large thermal mass

Filed under: Uncategorized — gasstationwithoutpumps @ 16:52
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Our poured-in-place concrete house has a very large thermal mass. We have not turned on the heat yet this year, but the temperature inside the house does not vary much. The outside temperature today varied from 38.1°F to 76.5°F (3.4°C to 24.7°C), but the inside temperature only changed from 58°F to 62°F (14.4°C to 16.7°C).  The outside temperatures are from a home weather station a couple of blocks away, and the inside temperature is from the thermostat, so they may not be identically calibrated, but both should be good to about ±1°F.

The breakfast room, where I do most of my work, fluctuates more than the thermostat, because the breakfast room gets bright sunlight once the fog burns off in the morning until about mid-day.  I’ve not measured the temperature where I sit, but I generally don’t need a sweater in the breakfast room until sunset.

We put off turning on the heat until it gets too uncomfortable in the house, even wearing sweaters. I expect that we’ll be turning on the heat around the end of November—at least, that’s what we did last year.

The natural gas we use costs about $100 a month for the four-to-five months a year when the heater is turned on, and about $30 a month the rest of the time (mainly for heating water, but also for the gas clothes dryer and the gas stove).  Switching from natural gas to electricity would be good for the environment (our local electricity is supposedly all from renewable sources), but would cost us a fair amount, both in replacing appliances and in increased energy costs—I don’t think we’ll be doing it in the next decade, unless electricity costs come down a lot or natural gas prices go up a lot.

2018 August 13

PG&E trying to screw people with home solar systems

Filed under: Uncategorized — gasstationwithoutpumps @ 11:22
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PG&E informed me that they were requesting an increase in minimum bill amounts for electricity “to reduce bill volatility”, but did not say how much an increase they were requesting. I looked at the complete language of the proposal at, but all it says is “Approval of this Proposal would increase electric rates for distribution customers by less than one percent; therefore, a statement setting forth PG&E’s proposed increases or changes to electric rates is not needed.”  So I have no idea how big a change they are proposing to the minimum bill.

I am currently paying the minimum bill amount monthly, so increasing that minimum amount will not “reduce bill volatility” for me, as bill volatility is already zero.  The change will definitely increase my bill, and probably by much more than 1%—but  it seems to be top-secret what my new bill will be.

So far as I can tell, PG&E’s primary aim is to extract more money from customers with net energy metering (NEM), making home solar energy systems less cost-effective, which works against California’s carbon-reduction goals.

If the increase in the minimum bill is less than 1%, then I have no major objection to the change, but if (as I suspect) it is much larger than the rate of inflation, then I strongly oppose the attempt to transfer costs primarily to NEM customers without even saying how much the increase is.

If anyone reading this blog is also a PG&E customer, you can send comments to, making sure to include “R.12-06-013” somewhere in the subject line.

2016 September 6

PG&E time-of-use Schedule E-6 gone

Filed under: Uncategorized — gasstationwithoutpumps @ 17:19
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The time-of-use rate schedule for electricity that I’ve been using (the E-6 schedule) is no longer available. It ended 2016 May 31, but those of us who already had it will be grandfathered in for a few years, but transitioned out of it by 2022.

E-6 was a good rate schedule for customers with solar panels. Under E-6, summer peak electricity is 34.159¢/kWh, but summer off-peak is only 14.854¢/kWh.  Winter part-peak is 17.071¢/kWh, and off-peak is 15.388¢/kWh. Note that the summer time fluctuation in rate is a factor of 2.3, so generating during peak times (which solar power does) and using electricity at night (which we do) results in substantial financial benefit, even when net usage is near 0.

The available time-of-use schedules now are much less favorable to the customer, especially to net-energy-metering customers.  ETOU-A has only 5–25% price differentials, and ETOU-B has only 10–30% price differentials, so the incentive to time-shift usage is tiny compared to E-6. The peak prices are about the same as under E-6, but the off-peak prices don’t drop nearly as much.

ETOU-A has higher rates 3pm–8pm weekdays, while ETOU-B has higher rates 4pm–9pm weekdays.  The summer/winter difference is only a change in the rates for the two time periods, not in when the higher charges apply (unlike the more complicated E-6 schedule, which has 4 time periods on weekdays, 2 on weekends in summer, and 2 on weekdays, 2 on weekends in winter. Winter is October–May for the ETOU schedules, but November–April for E-6. Because May is a month with high solar output, it is better for me to have it at summer prices.

The ETOU-A schedule has low rates up to a baseline amount, then somewhat higher rates.  Because of net-energy metering, I would nearly always be at the lower rate, which would be good for buying electricity, but is terrible for getting credit for energy I’m selling them.  The lowest rate on the ETOU-A plan

I’m certain that the E-6 schedule is much better for me than the new ETOU-A and ETOU-B schedules, but I don’t know by how much. PG&E has a rate-comparison tool that compares what bills one would pay with one’s current rate or any of the available alternatives. Of course, it does not work with E-6 plus net-energy metering—not only does it not work, with that rate schedule, but it then refuses to show what the bills would be with any other rate schedule—customers are left trying to calculate this themselves, which is unfair, because PG&E has all the data about how much electricity the customer used at different times, but the customer does not, and PG&E does not make access to the information easy.

When the time-of-use rate schedule changes in a few years, I suspect that my break-even time for the investment in solar panels will stretch out even further.

2016 July 30

Average annual power use

Filed under: Uncategorized — gasstationwithoutpumps @ 00:47
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I just got my “True Up” bill from PG&E—it has been about a year since the solar panels were installed. During that time, the panels generated about 2.63MWh of electricity (7.2kWh/day): 77kWh more than we used during the year. PG&E reimbursed me $2.11 for the extra electricity, but wiped out the $106 of Net Energy Metering credits that we had accrued from generating electricity during peak time and using electricity during off-peak times.

Next year, we’ll be facing a minimum delivery charge of about $120 for the year. If we follow the same peak/off-peak usage, that means that we could use about another $226 worth of electricity without increasing our bill (other than losing the $2.11 credit). That would be about 1.5MWh off-peak, or only 660kWh peak consumption. What that translates to for us is that I will be buying a dehumidifier for our house, to reduce the condensation on the walls. Current Energy Start rated dehumidifiers remove about 1.85 liters of water per kWh used, and I don’t think we need to remove 2775 liters of water a year (7.6 l/day) from our house, so the dehumidfier will add nothing to our electricity bill.  Based on reviews (in Consumer Reports and on Amazon), we’re looking at the 30-pint Whynter RPD-321EW Energy Star Portable Dehumidifier, is it has good performance in cool rooms (our house gets quite cool in winter, especially when we’re both at work) and is relatively easy to empty (we don’t have a convenient way to rig up a drain hose).

We are fairly light users of electricity by US standards. We used about 2.63MWh a year, but the US average is 10.932 MWh/year, and the California average is 6.744MWh/year [].  PG&E also reports what people in our area use: similar houses use 6.042MWh/year, and efficient similar houses use 3.262MWh/year [].

Part of the reason we use so little electricity is that we rely on natural gas for heating, hot water, cooking, and clothes drying, using about 433 therms a year.  Here we are not particularly efficient: PG&E reports that similar houses use 548 therms/year, but efficient similar houses use only 293 therms/year []. Shorter showers and setting up a clothes line would probably reduce our usage, but heating is the biggest chunk, and our house is already as cool as we are willing to live in.  We’ve invested in insulation over the years, but there is only so much you can do with a poured-concrete house for sane amounts of money.

A therm is about 29.3001 kWh, so our natural gas use is about equivalent to 12.7MWh—much more energy usage than our electricity!

We’ve been planning to buy carbon offset credits for our energy usage this year (see previous estimates in Solar lies).  Nothing for electricity of course, since we had a slight surplus there.  According to PG&E, natural gas produces about 6.1 kg CO2 per therm (and their electricity generation is about 238 g/kWh, only slightly more than the 208g for the same amount of energy from natural gas) [].

I calculate approximately the following CO2 production from our various uses this year:

My wife and I have considered taking another trip this year, to Boston, which would add another 4.9MT. Note that flying is by far the most energy intensive thing we do—reducing travel is probably the only way we could significantly reduce our carbon footprint.  As carbon offsets, we’re considering projects like, which cost $6–$10 per MT.  Do any of my readers know of good carbon offsets that aren’t scams or just enabling polluters?


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