Electric Rates (where you live)

Uhh.. I paid $32k -- $4k in tax credits.

 

You paid the "Prius Prius" price that most of us did who pre-ordered - that is to say, the price "to go before" the other Prii. Sorry, I could not resist.

 

I have the same situation. I also live in Roseville, and credit from our solar array almost completely cancels out whatever I am billed. I use little electricity, and thanks to the expansive fields out here my east and west-facing panels gather peak electricity efficiently. Last year the net amount I owed was nearly zero.

 

Re: home PV starter system

For June and July, my 1.6kW PV / 1.3kW AC system produced 428 kWh. Over the same time, the net billing meter rolled backwards 19 kWh, so we did achieve 'net zero' over a two month span.

Net-zero happened only because we were vacationing four weeks. While away, the house averaged 7kWh/day of production, burning only 3 of that for refrigeration, timed lights, modem (so I could monitor the PV system remotely) and other overhead.

An NREL PV calculator suggests this PV orientation and location should average 28.3% of its annual production in June and July. With local weather and tree impairments, I would have been happy with 1000 kWh/year of production, or 283 kWh for this period. So 478 kWh is thrilling.

At the same time, the new heat pump water heater (HPWH) slashed consumption. The old resistance heater was averaging 9 kWh/day. The new started at about 3 per day, falling to 2 as summer heated up. The clothes drier is now the hungriest appliance. While most of my laundry is put out for line drying when conditions allow, the spouse still heavily prefers the wasteful machine for hers and the common household stuff.

I hope to expand the PV to 4.3 kW this season, filling out the existing branch circuit. Annual Net-Zero will require something in the 5 to 8 kW range, requiring a second expansion with a subpanel and additional circuit(s) from the PV meter. That is next year's aspiration.

My house has been carbon neutral for nearly a decade, thanks to a public utility whose source fuel mix is 90%+ hydro. It gets less than 1% from fossil carbon, and buys enough renewable energy credits to completely offset that and its entire motor vehicle fleet.

But that is just a legal accounting trick. The DOE Power Profiler claims 45% of local electricity is from fossil carbon, coal and gas. Public utility preferences allow that undesirable energy to be shoved off to the private utilities on the bottom of the totem pole. I figure that producing my own carbon-free energy still helps by freeing up other non-carbon electrons for those less fortunate customers to use.

 

Good to hear! I know it's pie in the sky to dream of everyone with rooftop solar. I know it doesn't fit everyone's life style or economics. Still - the cool thing about having a system that Zeros out your entire home and transportation bill is that you no longer even bother thinking about what electricity costs in your area ... and you no longer have to bother comparing it to the difference in the cost of gas. There's nothing to compare.
.

 

Just to add another dimension to the discussion, we added a Ground-Sourced Heat Pump in Feb 2012, and this is one sweet, simple technology! except for the unholy garden mess during installation. Cools great, heats great, is practically silent, is very low maintenance, and doesn't cost much electricity to run.

If subdivision builders would automatically install this system while the subdivision is in its early construction stages and all the property parcels are wide open for drilling machinery access, the prices would really come down to nearly comparable prices for a standard HVAC system - with huge resultant lifetime HVAC efficiency gains for entire subdivisions. It's the individual retrofitting that's costly.

Regretfully, builders aren't known for their hankering to experiment

Here's a sample picture of what it takes to drill 228 feet in a small back yard:

 

My current target is only to zero out the dwelling, not the transportation too. But since buildings consume as much energy as transportation, or even more, this is still a giant leap forward.

The roof has space for 11 kW on the south pitch, without going to the less efficient east and west pitches. Some years ago the house would have needed all of that, but conservation has cut the load sharply, freeing up considerable potential capacity for a future plug-in vehicle.

Achieving the commonly voiced goal of reducing GHG emissions by 80% by 2050, means that I need to achieve a compounded reduction rate of 3.6% per year, from my starting year of 2006. (People just starting today need to move at 4.3%/year to meet that schedule.) Various efforts on the house were easily keeping ahead of that rate even without PV and HPWH, but going Net-Zero next year greatly exceeds my lifetime target in just a few quick steps.

Progress with our personal transportation is tougher. Hypermiling and occasional bicycle commuting covered several years of required progress, then getting a Prius achieved a bunch more. But another step is due in the next two years. Replacing the next vehicle with a hybrid should buy several more years until the EV market is sufficiently mature for my tastes.

PS:

I wish. But the current excess is due to this being the highest production / lowest consumption season (this location requires winter heat, but no summer cooling), with a major absence thrown in. Year-round Net Zero for the house alone will require at least a 3X, likely 4X, possibly even 5X expansion of this starter PV system. Winter shading loss is still TBD.

I would absolutely consider this for new construction. But as a retrofit, the ductless mini-split (i.e. single zone air-source heat pump) we installed in 2009 has displaced the great majority of our electric resistance heat load. The modern inverter-based units get most of the efficiency and other advantages of GSHPs.

 

My home is net negative for CO2 this summer too, although like Fuzzy I have to add some explanation:

The house itself over the past ~ 100 days has consumed 330 kWh -- about 3.3 kWh a day, 102 kWh a month. I also consume NG, to the tune of about 3 therms a month.

My local utility PNM changed the terms of their buy clean electricity program, and since it now seems as though the program might actually have the desired effect of adding clean kWh to the grid I participate by purchasing 90% (the max allowed) of my monthly use as 'clean' energy.

More definitive, but not actually my home, is my new behavior at work. I am usually the last person around in a shared office space at work in the evening, so I turn off lights. It is really quite amazing what full lighting takes: I calculated 1350 watts! And this is efficient T8 fluorescents. So the 7 times every two weeks I am at work I save 9.45 kWh each night, or about 143 kWh a month.

If I figure 1 kg CO2/kWh for coal electricity, and
7 kg CO2/therm NG*

The monthly totals work out to

+
102 kg CO2 electricity
21 kg NG

-
143 kg CO2 electricity saved at work
----------------------
(20 kg) CO2 a month before I presume any effect from the clean energy program through PNM.

* CO2 emissions from NG according to wikipedia is 68.4 grams CO2 per MJ. A therm is rated at 100,000 btu, equal to 105 MJ.

 

Can you or someone else here ... Provide some specific info for folks like me looking at installing solar?

Also, I have heard that some solar installations violate US code. Just relaying.

 

That really shows the value of having some task lighting at your workspace, when even efficient field lights consume more than does your entire home.

I'd want at least a desk light, a dozen or so LED or CFL watts, but some folks will do fine with just the computer display backlight.

 

Regarding codes, 'specific info' is strongly tied to your location, which isn't disclosed in your profile, and even to the particular inspector assigned to sign off on your electrical permit.

The basic benchmark guide is the National Electric Code. Article 690 covers solar photovoltaic systems, though it contains plenty of references to other sections. Print copies cost money, but it is now available for free online viewing at Free access to the 2011 edition of NFPA 70: National Electric Code.

Your state probably adopts most of the NEC, but with additions and deletions spelled out in the state Administrative Code. Your city or county may pile on more changes. Contact your local permit or code enforcement office for pointers. Find some local installers or solar fanatics willing to give DIY advice. It also helps to develop a friendly rapport with local inspectors. While they won't help design your system, they may offer helpful hints for cheaper / easier things that don't initially appear to meet the letter of the written code, but are acceptable functional equivalents.

And if you come back from a long vacation to find multiple letters from the code department's back office, issuing fines for not promptly responding to the letter they sent the day after you left on vacation, for not responding to a deadline they never previously mentioned, and threatening additional fines and shutoff of your home's power , don't get upset immediately. The individual inspectors just might still be very nice easygoing guys who will quickly help you get everything cleared up. Thanks Phil & Tom.

Your local jurisdiction might also have mechanical requirements. Mine didn't. Thankfully, as the electrical maze was bad enough.

 

We just hit our one-year anniversary with solar on the roof. System size is 4.94 kW DC / 4.32 kW AC. Total electricity produced: 6795 kWh. I'm still waiting for the true-up bill from PG&E, but it looks like we owe them about $44 for all the electricity we consumed over the last year. Monthly lease payments are $100, plus a $13 a month meter fee, and we come to a grand total of $1400 for electricity for the year. Before solar, that would've been between $2400 and $3000 for electricity for the year.

Very happy with solar so far...

 

Awesome. So what's your monthly consumption?

So the 6795 kWh is for the entire year (excuse the noob question) ?

Is the leasing of the panels through the utility itself? What's the other terms for this lease?

 

Great info. I am having a solar guy coming over next week.

 

Vulcanman, I would advise that you get a minimum of 3 estimates and bids for the install. I did and they were vastly different. I ended up with the one that I felt best suited my personality and desires and didn't try to shove something down my throat. (One company did and then kept calling me to find out why I was so stupid as to not lease from them so I could pay them a lot more over a span of several years....) All good companies will come and give you an estimate and offer for your property without any strings attached. This is a move where you definately want to explore all areas of what they want to do and do your own math based on facts. Whatever you get will be up to codes, or it will not be going on your roof! There are a lot of inspections and paperwork needed before the system gets 'blest' and officially can be up and running.

I have a 4.32 kW DC system and am right on the money to produce around the predicted 4700 kWh in the first year of operation. (Mine was put into operation last September.) I live in NYS so the same sized system is not going to produce quite as much as Southern CA.....

Good luck!

 

fuzzy - We swapped places for July. Last year, I had my highest ever production from my PV array. It was close to 1.1kw for the month. This year, down in the 600s. Typically, the June/July/August months can get me 800 on average. I was shocked when I got my July bill this year, because May & June were much lower than last year. I wondered how my usage doubled from the grid from a year ago - then I looked at production. I went from using 500ish last July to 1000 this July from the grid. Taking 250-300 kw production into account, I'm still 200-300 kw higher than last year total usage. I'm OK with that, because we suffered about 10-14 days of incredible heat during the month, plus I have the PIP now. I'm glad you got extra production, though! It's a great feeling to see the net-zero or near net-zero figures. How's the new water heater work, recovery wise? Granted, it's just me in my house, but in those instances where I need more hot water with guests, etc, I can't just downsize to 20gal tank. I looked into those HP ones a couple years ago, but at $1400 for the unit, I passed.

 

Monthly consumption before Solar was between 700 and 1000 kWh.

The 6795 kWh figure is the total Solar production for the year. Total consumption from PG&E was only 1832 kWh. This means that we generated more than 75% of our electrical needs via solar. The solar leasing company guaranteed that we would generate at least 5900 kWh in the first year. I'm pretty please with what it actually produced. It even beat what PVWatts said it would do.

Leasing of the panels/system is through a leasing company called Sungevity. They did the design and install of the system. The lease is for 15 years. Monthly payments started at $100 a month and go up 2.9% every year. No money down required, but we did end up putting some money down to bring the monthly lease costs down. At the end of the initial 15-year lease period we can extend the lease another 5 years, have them pull the system down off the roof, buy the system for fair market value, or have them design a whole new system and sign a new lease. Or they may choose to just leave the panels up there and let us have the system for free. We also have the option to pay off the lease early if we want.

We went with Sungevity because a friend worked there and got us some rebates/incentives. We seemed to have gotten a decent deal. It's not stupendous, but it's also not bad. Total out-of-pocket costs will be $23K at the end of the lease. According to Sungevity, the system is valued at $30K. Figuring in the cost of a replacement central inverter in year 10, and the rebates and credits available at the time, the amount we're paying to lease is about the same as the amount we would've paid to own the system. If I had had $30K at the time to pay for it outright, I probably would've done so, but it wasn't an option, so we went with the lease.

 

My comments were all aimed towards a do-it-yourself installation. If you have someone else do it, they will be the ones that have to know and comply with the code requirements. I don't have any good advice for selecting a contractor.

But do go read up at Home Power.

You location is much more productive than mine. While it is difficult to extrapolate through winter from just two summer months, results so far suggest that a system of your size would likely produce no more than 4500 kWh/year on my roof. But that is much better than the low-3000 range that I was mentally prepared to accept.

The lower site productivity here is one of the reasons I needed to go the cheaper DIY route to justify this project. Plus, as an engineer, this just felt like something I should be able to do myself. But not being a licensed electrician, the inspectors do have valid reason for fearing this sort of project.

 

Have you looked at PVWatts? PVWATTS v. 1
Lets you input your location, pitch of the array, direction of the array, and will spit out an annual estimate.

There's also NREL PVWatts Viewer which is a more sophisticated version of PVWatts that gives you a more refined site specific estimate.