[mikeeastman]

Well lets hope it was just a bad math day and not the Alzheimer starting to kick in    ,  those pesky decimal points. It is actually 10KW per day and going up to 12KW on very hot days, that require extra cooling. As my house is passive solar design I don’t us any more power to heat it in the winter.

genjamon, 10KW for a on the grid house is pretty good. Do you use any passive solar design to heat your house, living in Tucson you would have more solar gain and warmer temps than I have and I get 70-80% of my heat from the sun.

[ctviggen]

I bought solar panels (11.5kW) and I find it a very difficult calculation.  If we make more than we use (rare), we still have to pay $19/month.  When we get billed for power, we get billed on a sliding scale, based on energy consumption, which makes no sense to me, although the less you use, the more you pay.  I've paid anywhere from 17 cents/kWHr to 38 cents/kWHr.  The solar company, using a fixed energy cost, 4% increase per year, and no fee if you produce more than you use, estimated a return on investment of about 8 years.  I have no idea what the actual return on investment will be. It cost me $3.20/kW.

I'm also in CT, so we have periods of not much sun and snow on the cells.

[macrojack]

My panels produce 6500 KWH/yr. We use 4500 KWH/yr. Therefore we do not pay for any electricity --- but install costs $8.00/mo. for the connection and the meter readings. Only true for grid-tied systems, but if you want to use your utility company as a battery bank you will likely have to pay something. Mine is more than offset by my REC payment. This month I will receive a check from Xcel Energy in the amount of $20.24. That represents 3 cents per KWH produced during the previous billing cycle. That leaves +/- $12 to put toward my NG bill of $43 which includes the $8 meter fee on my electric.

This stuff is a little difficult to discuss on a forum because conditions and regulations vary so much from state to state.

[genjamon]

Well lets hope it was just a bad math day and not the Alzheimer starting to kick in    ,  those pesky decimal points. It is actually 10KW per day and going up to 12KW on very hot days, that require extra cooling. As my house is passive solar design I don’t us any more power to heat it in the winter.

genjamon, 10KW for a on the grid house is pretty good. Do you use any passive solar design to heat your house, living in Tucson you would have more solar gain and warmer temps than I have and I get 70-80% of my heat from the sun.

Given that my profession is working to advance environmental sustainability in many forms in higher education, I do try to be as efficient as possible, within reason.  10kWh/day is my ballpark baseline consumption excluding any HVAC use.  This is what we consume during the late fall, and early-mid spring months when I don't use any home AC or heating.  When it heats up, yeah even with 16 SEER AC units, I'm using more like 40kWh/day.  This year we had a hot spell in early March, with highs in the low-mid 90's, and I had to use AC that week.  Then didn't touch it until about the middle of this week when we got a ramp-up of temps, and we hit 104F on my back porch today.  So, today's been a bad day in terms of electricity consumption.     

Incidentally, Amazon just delivered a couple days ago a FLIR IR camera that plugs into my iphone/ipad.  So I had a fun hour this afternoon walking throughout the house with my iphone looking at all parts of my ceiling to find any gaps in insulation or thermal bridges.  We bought the house last spring, and after a year of living in it, I'm now beginning to plan various upgrades, including thinking through energy efficiency desires. 

In AZ, we just had our newly elected corporation commission approve new rate structures for all the major utilities in the state that eliminate true net metering, and instead only pay back to the homeowner the "avoided costs" to the utility for any new rooftop solar installations.  And part of these new rate structures also include new 3-tiered rate structures that incorporate demand charges into the equation.  Basically, your largest single 1-hour demand during 3-7pm time weekdays time window determines a surcharge fee added to your bill.  So, when those solar panels quit working around 5-6pm, and it's still 100+ degrees outside and your AC is still working hard, and you just fire up the electric stove for cooking dinner, it'll kill you.  It's around $5/kW of demand tacked on to your monthly bill.  Again, since it's only your single largest day of consumption, you can do great all month, but if you have a single day when the forces are working against you and your consumption spikes, you're screwed by an extra who knows how much.

Try figuring out your payback period for rooftop solar under those conditions!

[MtnHam]

In most of Northern California, PG&E is the supplier of electricity and the average cost is about $0.25/Kwh. With their tiered pricing, and time of use metering, if you are a heavy user, particularly of air conditioning in summer afternoons, you could be charged as much as $0.50/Kwh!

I installed a 6KW solar system 6 years ago when the price of solar panels was very high compared to today, but am glad I did.
I expect the system to be still producing 20 years from now when the cost of electricity will be substantially more than it is today.