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Post by somuchtodo on Apr 11, 2013 16:02:14 GMT -7
There is a good question. We are waiting for a transfer but it will be Nashville or Cincinnati.
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Post by tjwilhelm on Apr 12, 2013 8:53:07 GMT -7
Hmmm...that's a bit of a range. Nashville is at about 36 degrees latitude and Cincinnati is at about 39 degrees latitude.
Nashville has a high of about 5.85 peak-sun-hours/day in the summer; a low of about 1.76 peak-sun-hours/day in the winter; and, about 4.45 peak-sun-hours/day annual average.
Cincinnati has a high of about 5.79 peak-sun-hours/day in the summer; a low of about 1.50 peak-sun-hours/day in the winter; and, about 4.0 peak-sun-hours/day annual average.
This means there's over 10% more energy available in Nashville than Cincinnati. To be safe, if we size up a system for Cincinnati, it will be more than ample for Nashville.
Step (1) -- Loads: Can you give me more specifics here about the makes/models/sizes of the appliances you're looking at? Or, do you want us to pick new ones for you?
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Post by somuchtodo on Apr 12, 2013 13:49:19 GMT -7
I'm open to your knowledge of energy efficient appliances. Small conservative appliances are fine, maybe something that would be found in an efficiency apartment. I also like the idea of the solar water heating panel. You can never have too much hot water!!
Here's some basic criteria not counting the water heater:
1. Freezer (small chest style)
2. Fan
3. Small refrigerator
4. Lighting (a couple of overhead lights)
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Post by tjwilhelm on Apr 12, 2013 19:10:20 GMT -7
OK...I did not select the absolute most efficient appliances out there. Those will save watt-hours; but, they're awful darned expensive. Instead, I chose conventional, albeit energystar rated appliances from Lowes. The fan was tough. I couldn't find specific energy info online. For loads you will control -- lights and fan -- it's important to note that we need to know how many hours per day you will use these, and how many days per year. The time factor is critical -- it defines how much energy is used. Energy = Power x Time. Once you establish these time criteria, you're locked into these as your max useage for the winter. As you approach summer, the energy budget expands and you have more freedom of use. Here's a hypothetical load list. Check it out. Adjust it as you desire, and then we'll go to the next steps: www.lowes.com/pd_384304-46-MBF1953YEW_4294789499__?productId=3648432&Ns=p_product_qty_sales_dollar|1Maytag 18.5 cu ft Bottom Freezer Refrigerator (White) ENERGY STAR Item #: 384304 | Model #: MBF1953YEW 448 KWh/yr www.lowes.com/pd_354996-46-EH151FXTQ_4294857903__?productId=3530432&Ns=p_product_qty_sales_dollar|1Whirlpool 14.8 cu ft Chest Freezer (White) ENERGY STAR Item #: 354996 | Model #: EH151FXTQ 354KWh/yr www.lowes.com/pd_352216-75774-LA19DM/800/LED_4294801193__?productId=3408608&Ns=p_product_qty_sales_dollar|1Utilitech 13.5-Watt (60W) A19 Medium Base Warm White (3000K) LED Bulb Item #: 352216 | Model #: LA19DM/800/LED Qty. = 3? Use = 6 hours/day? If so, = 89KWh/year Generic floor or box fan = about 100W? Summertime, only? Use = 8 hours/day? 60 days/year? If so, = 48KWh/yr Annual energy use = 891KWh/yr for the entire year + 48KWh added for the summer. |
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Post by somuchtodo on Apr 13, 2013 13:29:52 GMT -7
OK...I did not select the absolute most efficient appliances out there. Those will save watt-hours; but, they're awful darned expensive. Instead, I chose conventional, albeit energystar rated appliances from Lowes. The fan was tough. I couldn't find specific energy info online. For loads you will control -- lights and fan -- it's important to note that we need to know how many hours per day you will use these, and how many days per year. The time factor is critical -- it defines how much energy is used. Energy = Power x Time. Once you establish these time criteria, you're locked into these as your max useage for the winter. As you approach summer, the energy budget expands and you have more freedom of use. Here's a hypothetical load list. Check it out. Adjust it as you desire, and then we'll go to the next steps: www.lowes.com/pd_384304-46-MBF1953YEW_4294789499__?productId=3648432&Ns=p_product_qty_sales_dollar|1Maytag 18.5 cu ft Bottom Freezer Refrigerator (White) ENERGY STAR Item #: 384304 | Model #: MBF1953YEW 448 KWh/yr www.lowes.com/pd_354996-46-EH151FXTQ_4294857903__?productId=3530432&Ns=p_product_qty_sales_dollar|1Whirlpool 14.8 cu ft Chest Freezer (White) ENERGY STAR Item #: 354996 | Model #: EH151FXTQ 354KWh/yr www.lowes.com/pd_352216-75774-LA19DM/800/LED_4294801193__?productId=3408608&Ns=p_product_qty_sales_dollar|1Utilitech 13.5-Watt (60W) A19 Medium Base Warm White (3000K) LED Bulb Item #: 352216 | Model #: LA19DM/800/LED Qty. = 3? Use = 6 hours/day? If so, = 89KWh/year Generic floor or box fan = about 100W? Summertime, only? Use = 8 hours/day? 60 days/year? If so, = 48KWh/yr Annual energy use = 891KWh/yr for the entire year + 48KWh added for the summer. These all look good and in the right usage ballpark. Planning to use the box fan for summertime use only is fine. Should we slap on a couple hundred more KWh for good measure? I'd rather have just a bit too much. I'm really curious at the cost for a system to drive this stuff. |
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Post by tjwilhelm on Apr 14, 2013 6:34:15 GMT -7
Rather than dive into a full and detailed system-sizing, perhaps it would be best to start with rendering a rough, "ball-park" cost estimate.
Rule #1 -- For a stand-alone, battery-based system, with solar-only input, you need to size the system for worst-case, solar-input conditions...December.
Rule #2 -- You need to treat a battery-based PV systyem like a leaky bucket...it's not a 100% conversion and transfer of energy from the sun to the end-use loads. There are inefficiencies and losses throughout the system.
Divide your 891KWh/yr (excluding the summer-use fan) by 365 days/yr. This results in 2.44KWh/day.
Multiply your 2.44KWh/day x 1,000. This results in 2,440Wh/day.
Now we have to apply rule #2, above...divide your 2,440Wh/day by .80 (we're assuming the system is "leaky" enough to lose 20% of what the sun provides, so we need to 20% larger "collector" to meet our needs). This results in 3,000Wh/day needed from the sun.
Now, apply rule #1 and look at the winter insolation (peaksunhours/day). Using your worst-case, in Cincinnati, divide your 3,000Wh/day by 1.5 hours/day. This results in the need for a 2,000W (rated at standard test conditions) solar-PV array.
The installed cost of a battery-based, solar-PV system can vary; but, a fair and safe number to use for a new system installed by a professional is close to $7.00/W. Multiply the rated 2,000W x $7.00/W and you end up with a rough, "ball-park" cost of $14,000.00.
HEY, MARC! Please critique! I'd appreciate YOUR perspectives thrown in here, too.
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Post by thywar on Apr 14, 2013 6:37:39 GMT -7
I find this very interesting and so I wanted to jump in here and (not to corrupt the thread) but say thanks to you guys for your willingness to share your professionalism and your expertise. I'm learning a bunch about this and again learning what an incredible group of people we have on here. Thanks
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Post by somuchtodo on Apr 14, 2013 9:00:01 GMT -7
It is great to get an estimate from someone with no financial interest.
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Post by somuchtodo on Apr 14, 2013 9:03:28 GMT -7
Rather than dive into a full and detailed system-sizing, perhaps it would be best to start with rendering a rough, "ball-park" cost estimate. Rule #1 -- For a stand-alone, battery-based system, with solar-only input, you need to size the system for worst-case, solar-input conditions...December. Rule #2 -- You need to treat a battery-based PV systyem like a leaky bucket...it's not a 100% conversion and transfer of energy from the sun to the end-use loads. There are inefficiencies and losses throughout the system. Divide your 891KWh/yr (excluding the summer-use fan) by 365 days/yr. This results in 2.44KWh/day. Multiply your 2.44KWh/day x 1,000. This results in 2,440Wh/day. Now we have to apply rule #2, above...divide your 2,440Wh/day by .80 (we're assuming the system is "leaky" enough to lose 20% of what the sun provides, so we need to 20% larger "collector" to meet our needs). This results in 3,000Wh/day needed from the sun. Now, apply rule #1 and look at the winter insolation (peaksunhours/day). Using your worst-case, in Cincinnati, divide your 3,000Wh/day by 1.5 hours/day. This results in the need for a 2,000W (rated at standard test conditions) solar-PV array. The installed cost of a battery-based, solar-PV system can vary; but, a fair and safe number to use for a new system installed by a professional is close to $7.00/W. Multiply the rated 2,000W x $7.00/W and you end up with a rough, "ball-park" cost of $14,000.00. HEY, MARC! Please critique! I'd appreciate YOUR perspectives thrown in here, too. This is great to know! Any suggestion on implementing the solar system in during the house construction process? +1 thanks again tj |
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Post by tjwilhelm on Apr 14, 2013 9:25:16 GMT -7
Keep in mind, we have NOT yet done a proper system-sizing. Step one (done) is to establish the load. Step two is to size the battery based on a compromise between desired "days-of-autonomy" and your realistic budget. The solar-PV array is sized last.
Another things to keep in mind...If you don't have to mount the PV array on the roof, don't. You can mount this on a "ground mount" rack, high enough to avoid damage from lawnmowers and kids, yet low enough to hose it off ocassionally, or pull off any snow that would hinder your production.
Pre-construction hints and tips...
Do a REAL solar site analysis prior to even designing the new house! Find your solar-sweet-spot -- the place where you have totally clear sky from 9a.m. till 3p.m., December thru June, with no concern of future shading due to growing trees -- and mark that as the spot for your future, ground-mount array.
Plan to have the house to the north of this location, and plenty close to keep wire runs short.
Plan to have your inside, balance-of-system (BOS) components on the south side of the house, close to the array.
If conditions permit, build a basement and keep your BOS hardware there, including your batteries.
Make sure you have enough wall space on the south side of the basement so you do not have to put your battery cabinet directly below your charge controller, inverter and switchgear...keep them separated, side-by-side.
When you pour the basement wall, build sch. 80 PVC-conduit "thimbles" into the wall (capped on both ends). Put in more of these than you think you might need. You'll need at least one to get your PV source circuit into the house, and the extras may come in handy later.
Those are off the top of my head.
Anyone else have ideas on this?
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Post by thywar on Apr 14, 2013 14:51:05 GMT -7
Someone please put a sticky on this for us. Thanks
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Post by somuchtodo on Apr 14, 2013 20:10:25 GMT -7
My dad was asking about starting with a smaller system and adding panels to it as finances allow. Any pro/cons to taking this approach?
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Post by tjwilhelm on Apr 14, 2013 21:12:37 GMT -7
You can do this almost any way you want; but, as you asked, there are pros and cons to any reasonable strategy.
If it were me; and, if I know the load list we have is pretty solid; and, if I could afford this new strategy, I'd approach it like this...
I'd figure out the full-size battery pack and full-size inverter needed for all the loads but I would cut the size of the solar-PV array in half...FOR NOW.
Here's why: The battery pack will be the hub and homebase of the system. A good battery pack should be built from individual batteries as close to identical as possible, including all being the same age, having experienced the same usage. It's not the best idea to put in half the batteries you need and then add to the battery pack a year or two later.
What this strategy does is save you half the cost of the array on the front end; but, it also imposes a pretty austere energy budget...you only get to use half of what you originally planned. It will work just fine (likely) in the middle of summer; but, as you approach winter you are getting closer and closer to a loss-of-load event. However, that will be in the winter time, and you could keep your food in picnic coolers on the back porch.
Just a few thoughts...
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Post by solargeek1 on Apr 14, 2013 21:13:49 GMT -7
Ok since we just built our aggressively passive solar home, ICF and now the 10KW system is online, here are a few more building tips.
First costs. If it is $14,000 +/- remember the 30% fed. tax credits in place until 2016. That makes your system cost only $9,800. Also check with your utility and state. Each may offer another rebate/cash back program.
Second BE THERE and know EVERYTHING about your system as it is being installed. Take copious pictures. Here is an example of this point.
We also put in some solar Thermal. We had done this before but are not plumbers. When they dug the trench to run the PV wires and thermal piping I asked about separation of the two in the trench. They assured me they were going to put a long Styrofoam piece in between and that would be enough.
Fast forward to the actual installation of the PV concrete pillars for the ground mounts - they hit the SOLAR THERMAL pipe. Even tho I showed them the pics and told them where it all was.
Well it was God's blessing in disguise. Despite our plumber betin totally Solar savvy, he was not there the day his guys put the pipes in the trench (when I was there) and the guys used fittings instead of absolutely mandated welded joints. We would have had a blow out once the unit heated up and it would have taken out the PV too.
EIther way, be there, and know everything. I did not know about the weld versus fitting - I pass it on to you.
Third: Write down everything the solar guys say. Or video them. Trying to figure out the OUTBACK menus so I can watch the system live is tough. So is watching the other metering panels unless they explain it to you over and over - or you write it down!
Ok if I think of more, I will add it:O
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Post by somuchtodo on Apr 15, 2013 4:45:51 GMT -7
Ok since we just built our aggressively passive solar home, ICF and now the 10KW system is online, here are a few more building tips. First costs. If it is $ 14,000 +/- remember the 30% fed. tax credits in place until 2016. That makes your system cost only $ 9,800. Also check with your utility and state. Each may offer another rebate/cash back program. Second BE THERE and know EVERYTHING about your system as it is being installed. Take copious pictures. Here is an example of this point. We also put in some solar Thermal. We had done this before but are not plumbers. When they dug the trench to run the PV wires and thermal piping I asked about separation of the two in the trench. They assured me they were going to put a long Styrofoam piece in between and that would be enough. Fast forward to the actual installation of the PV concrete pillars for the ground mounts - they hit the SOLAR THERMAL pipe. Even tho I showed them the pics and told them where it all was. Well it was God's blessing in disguise. Despite our plumber betin totally Solar savvy, he was not there the day his guys put the pipes in the trench (when I was there) and the guys used fittings instead of absolutely mandated welded joints. We would have had a blow out once the unit heated up and it would have taken out the PV too. EIther way, be there, and know everything. I did not know about the weld versus fitting - I pass it on to you. Third: Write down everything the solar guys say. Or video them. Trying to figure out the OUTBACK menus so I can watch the system live is tough. So is watching the other metering panels unless they explain it to you over and over - or you write it down! Ok if I think of more, I will add it:O Wow! Great info! I did not know they were still offering the credit at the fed level. I would never have thought to take pics or recording the instructions. Thanks!! |
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