Some rough numbers on how to get to a net-zero energy lifestyle
- Thread starter georgepds
- Start date
-
Active since 1995, Hearth.com is THE place on the internet for free information and advice about wood stoves, pellet stoves and other energy saving equipment.
We strive to provide opinions, articles, discussions and history related to Hearth Products and in a more general sense, energy issues.
We promote the EFFICIENT, RESPONSIBLE, CLEAN and SAFE use of all fuels, whether renewable or fossil.
- Status
OK.. so you use propane as a fuel.. how much did you use last winter? How much did you use before you put in solar thermal panels?
If it was 1 tank, than you used 400 gallons, or 36.4 MBTU ( 1 gallon of propane is 91 kBTU), more energy than is possible with that 110 ft^2 of south facing unshaded solar thermal
I think you probably used more.. the 18.7 from the solar , plus the 36.4 from a full tank of propane, adds up to 55 MBTU.. that's low for a normally insulated house is a class 5 cooling/heating zone
What unamed corporation?
How does one post on the internet without dealing with a corporation?
The cute little car seems to have gotten George's ire up. We have these disputes all the time....which is greener, conservation (turning down the stat) or efficiency (more insulation), DIY solar (low material use and no govt incentive) or net zero PV (greater CO2 reduction than DIY, but more complex/costly)?
Not really an either/or. Just part of a bigger problem, which is IMO all 'mental'. Every positive action we take can also be an excuse or cop-out for not doing something else. If someone turns their stat down to 60°F and puts on a sweater, half of us will scoff (for being uncomfortable for no reason). If someone else improves their house/heater to save the same amount at 70°F, the other half will scoff (for still 'wasting' some energy). If someone does 'all of the above' then they are heroes and we would all respect them.
And then there are the folks buying shiny green toys and driving to the recycling center in hybrid SUVs, and still using more any energy than any of us while being smug.
If you think 'green' is not being widely adopted b/c of cost, then you probably favor the DIY/conservation side. Conversely, I live in a high rent district where everyone could energy retrofit their big ol houses with the money in their sofa cushions, but they don't because they don't know any better or are misinformed, or wrongly equate green with discomfort/deprivation (i.e. conservation). I think we here can all be role models for our different communities.
Not really an either/or. Just part of a bigger problem, which is IMO all 'mental'. Every positive action we take can also be an excuse or cop-out for not doing something else. If someone turns their stat down to 60°F and puts on a sweater, half of us will scoff (for being uncomfortable for no reason). If someone else improves their house/heater to save the same amount at 70°F, the other half will scoff (for still 'wasting' some energy). If someone does 'all of the above' then they are heroes and we would all respect them.
And then there are the folks buying shiny green toys and driving to the recycling center in hybrid SUVs, and still using more any energy than any of us while being smug.
If you think 'green' is not being widely adopted b/c of cost, then you probably favor the DIY/conservation side. Conversely, I live in a high rent district where everyone could energy retrofit their big ol houses with the money in their sofa cushions, but they don't because they don't know any better or are misinformed, or wrongly equate green with discomfort/deprivation (i.e. conservation). I think we here can all be role models for our different communities.
As someone under 50, I was a kid during the last 'energy crisis' and spent countless hours designing/daydreaming about how I was going to build a passive solar house in the future to survive some energy apocalypse. I would've gone big for earthships and massive amounts of south facing glass and thermal mass, solar DHW, and riding out some temp swings. And I would do it all DIY and it would work great.
When my dad poured a ton of insulation in the attic in 1980 I was a super fan. 30 years later I realize he should've airsealed that attic first to get bigger savings, airsealed his rim joists to avoid the dehumidifier in the basement, and that asbestos filled vermiculite was not a good insulation to use! That's called progress.
30 years later we have affordable wind utility power, affordable rooftop PV, and can build superinsulated and net-zero houses (with an appropriate amount of passive solar gain) using off the shelf technology. These houses are more comfortable than conventional houses from the 1970s, and use far less energy and CO2 than the passive solar house experiments of the 1970s and 80s. And unlike those earthships, such houses COULD be adopted widely and become a new normal, now that would be real progress.
When my dad poured a ton of insulation in the attic in 1980 I was a super fan. 30 years later I realize he should've airsealed that attic first to get bigger savings, airsealed his rim joists to avoid the dehumidifier in the basement, and that asbestos filled vermiculite was not a good insulation to use! That's called progress.
30 years later we have affordable wind utility power, affordable rooftop PV, and can build superinsulated and net-zero houses (with an appropriate amount of passive solar gain) using off the shelf technology. These houses are more comfortable than conventional houses from the 1970s, and use far less energy and CO2 than the passive solar house experiments of the 1970s and 80s. And unlike those earthships, such houses COULD be adopted widely and become a new normal, now that would be real progress.
Circus
Feeling the Heat
Don't get me wrong, I'd like to buy a grid-tie PV system. But only large enough to break even every month. Energy harvested in the summer might not be savable for winter use.
http://northwindre.com/2013-wps-rate-case/
http://northwindre.com/2013-wps-rate-case/
Here in the west they only allow you about break-even energy PV panels if you tie to the grid, based on previous use. So it is hard to scale up if you are going to convert to something like an electric HP from oil, LP or wood. The issue with the PV grid connection is that it still requires a grid and an on-demand source of grid tied energy to be available 27/7: meaning oil, NG, coal, wood, nuke or hydro power. Also with any energy grid-tied system, burning oil, NG, coal, or wood on site is always going to be far more efficient than producing electricity and distributing it on the grid and then converting it back to heat, even with a HP. From the perspective of the engineer at the power plants trying to balance the loading of a grid with all these multiple power sources (all these tied mini PV and hydro systems with large electric plants) it can be a royal nightmare. In San Diego we simply used Mexico as a shunt. If there was an excess it went south, and if there was not enough we simply cut them off.
As for solar hot water systems, they do not always leak. Nor do you need water bottles and exotic storage systems. A simple water storage tank is highly effective. I installed many solar systems during the 70s/80s and lived with several different solar water heating systems. Depending on the latitude that you live at, they can produce space heat as well as DHW. I installed many chill chasers that were very effective, year round. The return on them is usually going to me far shorter than PV, they are essentially 'off-grid' and localized and they can be very effective and efficient.
Also if you want to play mind games with this stuff, why not move to a warmer climate that does not require a lot of winter heating and use a PV system for A/C when solar power is available? Or why not live in a cave like a lot of people do in places like Utah, and never need heat or A/C? Also insulate the crap out of wherever you live to reduce the energy needed to heat and cool the place. And in the longer run, what difference will any of this stuff make if we keep reproducing at the current rate? At some point, energy demand will strip energy supply, no matter how efficient, effective, or creative we get.
You know.. I'd like to install solar thermal ( especially solar air, which does not have the freezing problems) , but every time I do the numbers.. they come out low
For someone else's opinion, try here.. http://www.greenbuildingadvisor.com/blogs/dept/musings/solar-thermal-dead
"Green builders have an emotional connection to solar hot water systems, because they represent a fairly simple technology that's been around for over 100 years. But it's time to admit that a PV array is cheaper and less troublesome than fluid-filled solar collectors on your roof"
He's mostly interested in cost ,and does list conditions under which solar thermal is appropriate ( none of which apply to those of us who live close to the Canadian border)
For someone else's opinion, try here.. http://www.greenbuildingadvisor.com/blogs/dept/musings/solar-thermal-dead
"Green builders have an emotional connection to solar hot water systems, because they represent a fairly simple technology that's been around for over 100 years. But it's time to admit that a PV array is cheaper and less troublesome than fluid-filled solar collectors on your roof"
He's mostly interested in cost ,and does list conditions under which solar thermal is appropriate ( none of which apply to those of us who live close to the Canadian border)
Thanks , that helps. It appears net metering is dead in Wisconsin . The state government in Wisconsin appears to be filled with wingnuts these days, I'd blame them for passing this rate law as much as the electric utilities who promoted it.
The political environment is a bit different here in Massachusetts (though the law could be changed), and the Net metering support by state officials much stronger
If by mind games, you mean theoretical exercise, that's not what this is for me. I'm trying to implement a practical system exploiting the advantage local laws on net metering give. I currently generate about 3 MWh more than I need, and the heat pump will absorb that over production ( in a time shifted manner) . I'm trying to decide if I should install another 2.5 kV of solar to make up for the other 3 MWH to heat the house
As to why not move.. Well I like it here. I spent all last weekend kayaking in the great salt marsh,chasing cormorants, terns and egrets. Sure it's cold in the winter, but the work is good, and the play is better, and with the net metering , as implemented here, I can offset the cost of the cold. I also like the great desserts in Arizona , New Mexico, and Nevada too, and spent quite a lot of time working in them (mostly near Roswell, Barstow and Yuma) .. but I was born on the Atlantic, grew up on the shore, and feel out of place if I bed more than 1/4 mile from the ocean.
Also.. despite my current fascination with solar PV heat, I like to heat with wood in the winter.. there is little like it, and that, more than anything else, will probably limit the size of the solar PV I install
The rejection of NM in Wi is a proposal, not the law, Wi allows for net metering
http://www.dsireusa.org/incentives/incentive.cfm?Incentive_Code=WI03R
Net Excess Generation: Varies by utility; Generally credited to customer's next bill at retail rate for renewables and avoided-cost rate for non-renewables ...Credit is carried over monthly and reconciled annually, at the avoided-cost rate
Not sure of this , but I suspect this means that they sell you electricity at a higher price than they credit you for.. not a good thing if you want to heat your house with the energy you generated in the summer using solar PV and a heat pump
I have no real attachment or emotional connection to solar hot water (SHW) systems, but I have installed a lot of them. I also have a degree in electrical engineering and some experience with steam power generation and the grid.
I disagree with a lot of his statements and assumptions (of course he makes some counter statements at the end). Particularly the cost differences (SHW is still about half the cost of a PV system, especially if it is going to be on grid), his statements about SHW maintenance issues, and freeze protection issues. I never had a SHW system freeze up, ever. In either the ones that I installed or owned (in Northern California and Oregon, down to 8 deg. F.). Also the maintenance was all of 2 hours a year for me on any system. Cleaning the panels, checking/calking the roof seals, testing the circuits, looking for leaks. There was no need to drain any drain-down systems. Certainly SHW systems are better the farther south you are, and better below the 45th parallel. But they are likely better for most off-grid and even a lot of on grid systems, w/o the need for inverters, a much larger PV panel array, a two-way meter, a grid connection, or a heat pump water heater. Also he fails to mention some of the faults in PV: the fact that they degrade over time and the issues with PV array production quality lately. Also the drawback for either system here in the PWN is the fact that in winter PV and SHW panels are going to be rather ineffective at generating any hot water.
In the future costs may likely come down enough to make a PV system economical just for heating with. Comparing these two systems though, wood space heating is far cheaper for me. Water heating costs me all of $25 a month in electricity. For a SHW system costing $8k, the return would take 27 years to re-coop the cost, so why bother. That is if I were live here for another 27 years, which is highly unlikely. I am not even likely to live that long. The cost of a PV system would be at least twice that, which males payback beyond the likely life of the PV system, or even this house or myself (similar to the SHW system, but far more expensive). Both systems would qualify for rebates and tax incentives here in this area.
And to counter your posted SHW vs. PV web opinion, I offer this one, which I think is far more realistic:
http://www.homepower.com/articles/solar-electricity/design-installation/pv-vs-solar-water-heating
Yes, any power company is going to pay less for the excess energy than they will charge you for it, and you will also have to pay for transmission and distribution fees for the electricity used (the cost of maintaining the grid), and any added taxes on the electricity in your area. At least that is the way it is here. So you are going to have to generate more electricity in summer than what you use for winter heating.
I'm beginning to see that Massachusetts is a special place, with respect to Solar PV
First capital cost.. you can have PV installed for ~$4/watt here (not the $8 to $10 in the HP article). Next there are the rebates : 30% federal, 15% state tax credit up to $1000, Mass CEC install incentive of $0.40/watt up to 5 kW (or $0.80/watt up to 5 kW if your house assesment is less than the median for your county).. What this does is reduce capital costs, installed , to ~$2/ Watt
Next recurring cost: There is the credit from the electric company.. it 's a full credit , and includes all those other charges that Stihlhead mentioned.. in fact it's so good they divide it into three parts
Net Met Cr Other $0.09543 per kwh
Net Met Cr $0.03539 first 600 kwh
Net Met Cr $0.04018 next 600 kwh
That last one is to reflect the fact that if you used more than 600 kwh in a month, they would charge you a bit more.. so if you export more than 600 kwh / month they will pay you a bit more
Finally, there is the SREC market.. For each MWH you generate, you get a SREC credit you can sell, this is currently ~$240/ credit, and the right to sell credits is guaranteed for 10 years (and at my house each kW installed generates about 1.4 MWH/year)
The net effect is to bring payback period down to ~4 or 5 years.. after that it is all gravy.. My equipment is warrantied to 25 years, with panel degradation guaranteed at less than 10%/ decade.. I use enphase microinverters.. this allows me to monitor each panel separately.. and if one goes bad.. I know which one, and the rest keep on working.. On the whole.. the system will outlive me
So the hitch is the electric compay will be happy to credit you, but will never send you a check. What that means is that most people install to cover what they use (~6 MWH/year or, roughly, 5 kW). But PV finances are so good, it's worth the price even if the electric company does not pay you back ( it increases payback by a factor of two) .. What I'm trying to do here is find other places to use that electric company credit to offset costs that I would have to pay anyways ( heat for example) .. and so long as I'm doing it, I might as well use a heat pump to squeeze the most benefit from the credit
First capital cost.. you can have PV installed for ~$4/watt here (not the $8 to $10 in the HP article). Next there are the rebates : 30% federal, 15% state tax credit up to $1000, Mass CEC install incentive of $0.40/watt up to 5 kW (or $0.80/watt up to 5 kW if your house assesment is less than the median for your county).. What this does is reduce capital costs, installed , to ~$2/ Watt
Next recurring cost: There is the credit from the electric company.. it 's a full credit , and includes all those other charges that Stihlhead mentioned.. in fact it's so good they divide it into three parts
Net Met Cr Other $0.09543 per kwh
Net Met Cr $0.03539 first 600 kwh
Net Met Cr $0.04018 next 600 kwh
That last one is to reflect the fact that if you used more than 600 kwh in a month, they would charge you a bit more.. so if you export more than 600 kwh / month they will pay you a bit more
Finally, there is the SREC market.. For each MWH you generate, you get a SREC credit you can sell, this is currently ~$240/ credit, and the right to sell credits is guaranteed for 10 years (and at my house each kW installed generates about 1.4 MWH/year)
The net effect is to bring payback period down to ~4 or 5 years.. after that it is all gravy.. My equipment is warrantied to 25 years, with panel degradation guaranteed at less than 10%/ decade.. I use enphase microinverters.. this allows me to monitor each panel separately.. and if one goes bad.. I know which one, and the rest keep on working.. On the whole.. the system will outlive me
So the hitch is the electric compay will be happy to credit you, but will never send you a check. What that means is that most people install to cover what they use (~6 MWH/year or, roughly, 5 kW). But PV finances are so good, it's worth the price even if the electric company does not pay you back ( it increases payback by a factor of two) .. What I'm trying to do here is find other places to use that electric company credit to offset costs that I would have to pay anyways ( heat for example) .. and so long as I'm doing it, I might as well use a heat pump to squeeze the most benefit from the credit
semipro
Minister of Fire
Check out the simple drainback systems at Gary's site builditsolar.com. Gary is a regular here.
Solar thermals still pays if you DIY.
jebatty
Minister of Fire
It's a bit of bummer for me on a proposed solar PV install. First, for net metering the power company requires a variety of disconnects and installation procedures which raise the cost, and second, for unshaded solar I need to do a ground mount with concrete footings installed a fair distance from the house connection point, which involves trenching under a road and a long cable run. Installed cost/watt is about $4.70 for 7.95KW before credits. The only credit is the federal tax credit, no state credits or incentives. The plus side is that the net metering law requires the power company to credit/pay me at the full retail rate, a complete off-set to what we use.
DevilsBrew
Minister of Fire
- Apr 21, 2013
- 687
- Status
Similar threads
