This SOLAR PLAN MUST be Possible>>

13

Comments

  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: This SOLAR PLAN MUST be Possible>>

    Yea--knowing you Marc--you probably are busy insulating your "ducks" with duck tape.... Hmmm, that sounds even better in French "isolantes vos canards avec bandes de canards". :p

    Remember, Marc is really near where the sun really does never set (at least during summer). ;)

    Treblig,

    Only if your ducts are very well insulated--Otherwise, you run the risk of simply bringing in more heat to the home--and running your bills up more.

    Perhaps a second mini split (or a central heat pump with several evaporators) would help (yea--this is all getting towards replacing the main A/C--don't want to go there yet).

    By the way, how do you heat your home? Many of the mini-splits have a heat pump option (and there are heat pump water heaters too).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TrebligTreblig Registered Users Posts: 23
    Re: This SOLAR PLAN MUST be Possible>>

    I'v never seen a heat pump where I live, don't think they are practical here. We have a gas heater built into the AC plenum. It comes on about 3 times a year. Even if it never it never came on we wouldn't freeze, we'd just put on an extra layer of clothes. The heat pumps carry an extra cost for the heater portion (gas is super cheap and we don't use much of it). In fact the gas stove probably uses way more gas than the heater.
    Coot,
    I already have a 5000 BTU (9.7 SEER) window ac in the bedroom (did that just two weeks ago, didn't know about mini-split at the time)). It's really helped with the problem. I'm looking at a mini-split as something to run interference on the 4ton. Like I said, even it only cuts $50 off my monthly bill I'll be way ahead in just two years. Wen the main unit dies I'll put in a mini-splitfor the whole house (but might be 8-10 years from now).

    I also like the idea of being able to run the mini-split (115V) off a small generator (better to have two rooms cool than none during a power outage).

    Gil in Tex
  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: This SOLAR PLAN MUST be Possible>>

    You have to read the specs carefully--I believe the Sanyo (SEER ~ 16) is a 120 VAC unit... The 26 SEER units (many, all, some?) may only be 240 VAC models.

    Sanyo Mini-Split AC
    Time to Buy some Mini-Split A/C systems, your thoughts?
    Sanyo mini split AC (inverter/variable speed)
    Mitsubishi mini-split 26 SEER
    RV A/C System--Would Sanyo Mini-Split work?
    More panels & window AC or efficient mini split AC?
    Ac vs gshp

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    BB. wrote: »
    Yea--knowing you Marc--you probably are busy insulating your "ducks" with duck tape.... Hmmm, that sounds even better in French "isolantes vos canards avec bandes de canards". :p

    -Bill

    may be better than trying to insulate against earth-quacks.:p:p

    as to the savings in putting in 1 minisplit at seer 26 it would cut in half the cost of cooling in only that section of the home if it stays isolated. being it's 1/3 of the house load then the overall savings would be roughly 1/6th. overextending the unit to cover those other areas could strain the minisplit and lead to a breakdown or shorter lifespan. minor overlaps you might get away with once in awhile.
  • Dr. StrangeloveDr. Strangelove Solar Expert Posts: 49
    Re: This SOLAR PLAN MUST be Possible>>
    Treblig wrote: »
    I'v never seen a heat pump where I live, don't think they are practical here. We have a gas heater built into the AC plenum. It comes on about 3 times a year. Even if it never it never came on we wouldn't freeze, we'd just put on an extra layer of clothes. The heat pumps carry an extra cost for the heater portion (gas is super cheap and we don't use much of it). In fact the gas stove probably uses way more gas than the heater.

    Where are you in TX Gil? My house out in Hill Country had not one but two heat pumps. The only "extra" cost of a heat pump over an AC is the switching valve. When in heating mode, a heat pump is nothing more than an AC in reverse, cooling the outside and dumping the heat inside. I wish I had known about mini-splits back then, because I had a couple of ancient balky, clunky, noisy and power hungry units. I didn't replace them because all the HVAC shysters that came out to give me a quote coughed up ridiculous prices in the $10K - $20K range for more of the same (the worst was Sears with their high pressure "save 10% if you sign right now!" tactics - how do they sleep at night?). My heat pumps were barely sufficient for the task: in the Summer, at 115 degrees outside, they ran nearly continuously. In Winter, when it got to 20 degrees, they ran almost full time in addition to the "aux heat". You might want to think about the energy savings from day one with a mini-split system rather than run the old 4 ton AC into the ground. If the newer system saves you $50/month now, that's $600/year and $6K over 10 years if your AC lives that long. It's a false economy to keep the older POS simply because you have capitalized it already. Perhaps you can donate it to some charity for a tax write-off. I know that my local animal rescue shelter needed a new cooling system while I was there. I certainly hope they didn't get quotes from the same carpetbaggers I talked to.

    Andrew
  • TrebligTreblig Registered Users Posts: 23
    Re: This SOLAR PLAN MUST be Possible>>

    I've done lots of research and I've found a few 115V minisplits like this one

    http://www.acsuperstore.com/Merchant2/4.12/00000001/catalog/c705.html

    Although this on is a heat pump, there are others I've seen with 26 SEER rating that run 115V, I'm looking for a 115V so I don't have to run another 220V line. I've seen some 18000 BTU mini-slits that are also 115V.
    My ducts are the newer type well insulated and well sealed. i really don't expect the mini-split to carry the whole house. My plan was to use it to help keep the house comfortable during the hottest part of the day, simply to keep the 4ton from having to run so much.
    I imagine during the wintertime when temperatures "nose dive" into the 70s the mini-split could easily carry the whole house. That would be great!!! And yes, when it's 70 outside it gets up around 85/90 degrees inside once the attice heats up plus the humidity is still in the 80% range in the winter. So 80/90 degrees plus 80% humidity equals MISERY!!
    Oh yea, 1/6 of my current electric bill is $50 and remember, August is always our hottest month!! What month are we in.....???


    PS- only 6 month to our 3 days of winter!!! I'm not complaining, I love the heat and humidity, I'm outside all day working on the hot rod. I just don't like the kids being inside the house if it's hot. Oh yes, I lived up in Cheyenne, Wy for three years (that's 1000 ft above Denver), liketa froze to death!!!!!!!!
    Gil in Tex
  • TrebligTreblig Registered Users Posts: 23
    Re: This SOLAR PLAN MUST be Possible>>

    Dr. strangelove,
    I live in Corpus Christi, but I love the Hill Country, in fact I'm headed for Fredricksburg this month for the swap meet at Lady Bird Johnson Park in three weeks. Been to Enchanted Rock, Perdinales Falls, bat cave (outside of Fredricksburg), Peach Orchards, etc, etc Many many times!!
    As for mini-split prices, I'll scavange the internet and find the best deal. I have friends that can hook everything up for me (AC pros who will do it almost for free...6 pack).

    Gil in Tex
  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: This SOLAR PLAN MUST be Possible>>

    Also watch what is going on around and inside your home (shade from trees/plantings, kids with 120" TV and three desktop servers always left on, etc.)...

    I pretty much have replaced my older entertainment stuff (stereo, TV, desk top computers) with smaller stuff (laptop, MP3 players, etc.)...

    We still have one few year old 32" flat screen LCD TV in our bed room, and the ~150 Watts from it can keep our room pretty warm in cold weather. Add ~100 watts per person, and and we are putting some heat into the room.

    For you, where you have to pay to remove any heat generated in the home outside--I would suggest getting a Kill-a-Watt meter (or similar) and see what is left on/used/on standby power (like DVR's, cable+sat boxes, etc.) and see if you can both cut down your direct energy usage and the indirect heat removal costs too.

    There are also whole house monitoring systems (single channel, multi-channel, Internet access, etc.)... If nothing else, you can have fun nagging your kids with the data. :roll:;)

    Some of the stuff that I have seen borders on crazy... Putting a large ceiling fan in an office to help keep it cool (no A/C) and they put 4x 100 watt lights in it... The fan now becomes a big electric heater.

    I am not a huge fan of CFL's (light is a terrible color, slow to light, don't like to be switched on and off a lot, sometimes expensive) and my wife hates them... However, I replaced with CLF's all of the lights that are used daily--The reduction in power usage (yea, we only use less than 300 kWH per month--big deal:roll:) and how much cooler the home was with these lights--converted here (enough) that we use them everywhere now except for certain fixtures (I use screw in bulbs with halogen capsules--they work really well on dimmers and decorative fixtures--although not cheap).

    LED lamps--they are getting there. My suggestion is to only get one of a type and use it for upwards of 1 year before replacing every thing. LED's don't always look "right" but their bigger problem is they still generate some waste heat that is really bad for the LED's and electronics. There are enough LED's that last only a few hundred hours before they fail--that I would not spend $$$$ for a mass change out just yet--Try a few different brands/models for a year first and see which ones last in your home.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TrebligTreblig Registered Users Posts: 23
    Re: This SOLAR PLAN MUST be Possible>>

    I have CFLs thoughout the house and even in the garage outside. Got a few solar powered flood light in the yard. Planted three live oak trees to help block the sun but they are double edged swords...when we get hurricanes and windstorms the big limbs end up putting big holes in the roof when they fall so you can't put trees too close to the house.

    ordered some "daylight" CFLs online (e3 company I believe), man they are the cat's meow...they actually lite up the room with something that looks like sunlight...very, very happy. Folks have come inside the house and can't belive the light quality....plus it saves on the electric bill.

    A Kill a watt is probably a good idea but the kids aren't going to like it.


    Gil in Tex
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    wild01 wrote: »

    I will wager you are looking at several costly requirements.

    3. must have a bizarre arcane outdated and costly anti-islanding feature built in (keeps the system from electrocuting utility workers who are working on lines they think have been turned off. $$$$$$$$$$$

    So, you'd repeal UL1741? You'd rather that grid-tied inverters keep their outputs (and therefore the local grid) energized in the event of an outage? Or are you being ironic?

    Incidentally, safety for line workers is not the only reason for anti-islanding. Who knows what sort of a load the external connection would present to your inverter if the grid went down and your inverter kept running, or tried to?
  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: This SOLAR PLAN MUST be Possible>>

    GT Inverters too expensive?

    Xantrex GT4.0N Grid Tie Solar Inverter
    Price: $2,542.50
    • $2,542.50 / 4,000 watts = $0.64 per watt end customer price (plus delivery)
    Our aim for wholesale price for medium production levels of straight forward 1,000 watt custom AC to 5/12/-12 volt switching computer power supplies back in the early 1980's--$0.50 per watt

    I doubt that the Anti-Islanding adds very much to the overall cost of the inverter--Just some computer code and a few gates to turn off is the grid "dies".


    Realistically--There is no way that you could have the inverter operate when the "grid fails"... You would at the very least need an AC Transfer switch and a mode switching Inverter (GT to Off-Grid) if you wanted to make a "Hybrid" GT/OG power inverter/system.

    Xantrex XW6048-120/240-60 Hybrid Inverter-Charger
    Price: $3,400.00
    • $3,400 / 6,000 watt = $0.57 per watt -- End customer price
    I am suitably impressed as a design engineer. Even a little curious that the XW Hybrid inverter with a whole bunch more parts is actually less expensive ($/watt) than a "simpler" pure GT Inverter. Bet there are some market forces involved here (GT inverters are high volume vs XW Hybrid Inverters--And the market supports the higher GT price because of government incentives vs less for pure Off-Grid systems?)

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dr. StrangeloveDr. Strangelove Solar Expert Posts: 49
    Re: This SOLAR PLAN MUST be Possible>>

    Ah, Corpus Christi, that makes a lot of sense. I still recommend a heat pump split-air system. This way your HVAC system will depend on only one motive energy source. And heat pump heat is far more efficient than resistive heating (which is the electrical equivalent of a gas-fired heater). Shoot, in the Summer, you could probably collect significant amounts of distilled water from your evaporator condensate. While the Hill Country has its charms, I can tell you that I prefer the light morning rains that just passed by, and the expected clear & sunny day climbing to the high 80's predicted for today. Especially since I expect to spend the day building a rock wall with a group of Tongans.

    Bill, the anti-islanding feature seems to require some additional hardware to "ping" the grid to measure "stiffness". That is necessary to allow the function to continue to operate with multiple GT inverters in parallel. Does anyone have any detailed information about how this is implemented and what are the thresholds for detecting grid failure? I can envision a situation where a neighborhood, sharing a single split-phase transformer, has multiple grid-tied RE systems at different homes. What happens when this local grid becomes "stiff enough" to island? The way I see it, UL 1741 implementations are kind of a hack - the future of distributed energy production on a single grid will require either out-of-band signaling or affirmative in-band signaling to control production, distribution and subnet shut down. Expect the utilities to run kicking and screaming to the PUC about how terribly burdensome this will be, and can't we go back to the good old days where they made power and cleaned out everyone's wallet?
  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: This SOLAR PLAN MUST be Possible>>

    Years ago, as I recall, only Germany had a "grid impedence check"--Of course, it would not stop vendors from making the test common across their entire product line.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • techntrektechntrek Solar Expert Posts: 1,372 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    Treblig wrote: »
    ... there are others I've seen with 26 SEER rating that run 115V ...

    Please post some links, I would love one with both of those specs. The only 26 SEER units I've found are all 240 volts.
    4.5 kw APC UPS powered by a Prius, 12 kw Generac, Honda EU3000is
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    Treblig wrote: »
    The other big difference (this holds true in very hot climates) is that the fewer times the 4ton comes on the fewer times the whole house will get "pumped" full of very hot attic air which "bakes" the ducting in the attic when the AC is not running. This happens when the 4ton initially turns on and pushes all the hot air out of the ducts, you feel it everytime it comes on. Not sure how much saving that would give me but I know that cooling down a house that just had 30/40 cubic feet of 90 degree air pumped into it can't be the smartest way to live!!!
    If the air in your ducts are heating up that much in between AC cycles you definitely need to get more insulation around them... Most of the "stock" insulation for ducts is like R6-12 at best - so when your AC is running that's like extending your living space into an area exposed to 130F and minimal insulation!

    If you don't have R40 in the attic already get that done and perhaps some radiant barrier as well?
  • TrebligTreblig Registered Users Posts: 23
    Re: This SOLAR PLAN MUST be Possible>>

    drees, I really appreciate the suggestion and you may be correct.
    Now that I have the small window unit in the bedroom I can keep the house at 78 all day long and still freeze my "cookies" off at night. The 4ton doesn't come on that often during the day so I don't think thicker insulation on the ducks would help. Now that the 4ton stays on 78 during the day it stays off for longer periods of time. The thicker insulation would surely heat up because the AC stays off so long between cycles so there is plenty of time for the ducts to heat up. Like I said, you might be correct...I'd have to spend the extra money to find out?? To make things worse...I have a very low attic, as it stands now I can barely slide (on my belly) past the ducts when I have to work up there if I get bigger ducts I won't be able to go up there at all. The temp at the ducts (in the middle of the day) is 64 degrees....except when they first come on.
    The radiant barrier...if by that you mean spraying the roof with a reflectant coating, now that is cheap and easy to do!!!!! And it makes the roofing shingles last longer!!


    techntrek,

    I checked all my saved sites and you may be correct. The highest SEER rating on 115V mini splits is 22 SEER on a Fredrich M09CH 9000 BTU air conditioner. The 26 SEER I found (Mitsubishi "Mr Slim" ac/heat is 220V). But still, 22 SEER is a big improvement over my 13 SEER 4ton and the 22 SEER won't require running a 220 line.

    Dr Stangelove,
    I really hate spending the extra cash on any kind of heat pump as we barely use the heater, I'm serious, the thing only comes on a few times all winter (well, not really winter, it's more like the mild summer season during Dec and Jan). Most of winter it's in the mid 80s with a few 70s thrown in there. Yes, we do get a "cold front" now and again but the very next day it's back up in the 70s/80s again. Even the one time it snowed a few years back, the next day it was high 70s (with snow on the ground), the kids had to hurry and make snowmen before the snow melted...and it didn't take long.

    Gil in Tex
  • BB.BB. Super Moderators, Administrators Posts: 28,879 admin
    Re: This SOLAR PLAN MUST be Possible>>

    I believe the Radiant Barrier that is being discussed here is typically some sort of reflective aluminum foil.

    Beware--In Australia, they had quite a bit of problems with connecting the aluminum barrier to the house wiring. Fire and Electrocutions resulted...

    Homeowners Scrap Foil Insulation:
    As at last Friday, 46 per cent of householders had chosen to have foil removed from their roofs, while a further 40 per cent of householders had safety switches installed - all at taxpayers' expense.

    Fourteen per cent of householders had safety inspections only.

    The Government has pledged to inspect all of the 50,000 homes fitted with foil under its disastrous $2.45 billion home insulation program.

    The program was axed after it was linked to four installers' deaths, dozens of injuries, more than 100 house fires, and reports of dodgy installations and fraudulent operators.

    Be sure of what you are doing (or what contractor you hire). If done wrong--it can be a huge safety hazard.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: This SOLAR PLAN MUST be Possible>>

    Radiant barrier I have used is mylar - non conductive - over "bubble wrap" core.
    A top layer of rigid foam insulation, even 1", can be more effective in some cases.
    You need a good insulation contractor to evaluate the particular condition of your house and correct any shortcomings/make improvements.
  • TrebligTreblig Registered Users Posts: 23
    Re: This SOLAR PLAN MUST be Possible>>

    Interesting!!!
    Around here, in South Texas, companies spray a reflective, rubber type, flexible material on the roofing shingles. It's sprayed on the roof top only. At least I think it's rubber, it may be some other type of flexible material, but it's definitely spayed on the roof after the shingles are layed. It cuts down on heat penetrating into the attic by reflecting the sunlight. Other companies around here spray the rafters from the under side...here one of their advertisements>>>


    http://www.aaaac.us/rb/

    Radiant Barrier Benefits

    •Lowers heating and cooling costs year round
    •Reflects 70% of radiant heat
    •Non-toxic/non-carcinogenic
    •Not affected by moisture or humidity
    •Dual protection: The metallic aluminum pigment reflects radiant energy or heat from the
    sun during the summer months and in the winter the same microscopic aluminum particles
    prevent radiant energy from leaving the building.
    •Environmentally Friendly! Contains No ammonia, No alcohol, No solvents!


    I wonder what would happen if I did both, the outer one would reflect 50% of the heat and the inner one would reflect 70%....that's 120%...it would actually cool my attic!!!! I know, that isn't possible, but you guys have got my brain thinking about some good ideas!!!

    Gil in Tex
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    Treblig wrote: »
    The radiant barrier...if by that you mean spraying the roof with a reflectant coating, now that is cheap and easy to do!!!!! And it makes the roofing shingles last longer!!
    Not what I meant (see other posts) but a white/cool roof is always a good idea in hot climates, too. :)
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    Treblig wrote: »
    Interesting!!!
    Around here, in South Texas, companies spray a reflective, rubber type, flexible material on the roofing shingles. It's sprayed on the roof top only. At least I think it's rubber, it may be some other type of flexible material, but it's definitely spayed on the roof after the shingles are layed. It cuts down on heat penetrating into the attic by reflecting the sunlight. Other companies around here spray the rafters from the under side...here one of their advertisements>>>


    http://www.aaaac.us/rb/

    Radiant Barrier Benefits

    •Lowers heating and cooling costs year round
    •Reflects 70% of radiant heat
    •Non-toxic/non-carcinogenic
    •Not affected by moisture or humidity
    •Dual protection: The metallic aluminum pigment reflects radiant energy or heat from the
    sun during the summer months and in the winter the same microscopic aluminum particles
    prevent radiant energy from leaving the building.
    •Environmentally Friendly! Contains No ammonia, No alcohol, No solvents!


    I wonder what would happen if I did both, the outer one would reflect 50% of the heat and the inner one would reflect 70%....that's 120%...it would actually cool my attic!!!! I know, that isn't possible, but you guys have got my brain thinking about some good ideas!!!

    Gil in Tex

    That is elastomeric roof coating. I've used that too. Doesn't stand up in our climate here. We can't get the aluminium type, though. I just found that out when I went looking for it to do a barn roof. :grr
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>

    In answer to the question of whether it would be better to run the fan all the time to keep the "ducks" (ducts) cool, I'm pretty sure the answer is no. The heat transfer rate into the ducts is what it is, and that heat is going into the air in the ducts. If you run air through them continuously, you are heating up a lot of air a little bit rather than heating up a little bit of air a lot. You might also argue that as the temperature of stationary air in the ducts approaches the temperature of the air in the attic, the heat transfer rate goes down and eventually stops, so heating up a little air is better. Add to that the expense of running the fan all the time, and I think it's a no-brainer.
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    ggunn wrote: »
    In answer to the question of whether it would be better to run the fan all the time to keep the "ducks" (ducts) cool, I'm pretty sure the answer is no.
    You are right for all the right reasons. :)
  • wild01wild01 Solar Expert Posts: 97 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>

    have you considered adding an attic vent fan or 2?
  • TrebligTreblig Registered Users Posts: 23
    Re: This SOLAR PLAN MUST be Possible>>

    Yes, last summer I calculated my attic space (area) and purchased an attic fan. Then I calculated how much venting to install in my eaves and installed sufficient venting to allow the new fan to evacuate the hot attic air easily. It helped alot but this year it's been particularly hot....yes, even hell has times when it is hotter than normal. FYI, I have the fan set to turn off at 80 degrees so that it doesn't run 24/7 and guess what.....the fan comes on around 9:30/10AM and turns off every night around 10/11PM....AMAZING!!!. I love the heat but not inside the house. Of course the 95%/100% humidity doesn't help.

    Gil in Tex
  • wild01wild01 Solar Expert Posts: 97 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    ggunn wrote: »
    So, you'd repeal UL1741? You'd rather that grid-tied inverters keep their outputs (and therefore the local grid) energized in the event of an outage? Or are you being ironic?

    Incidentally, safety for line workers is not the only reason for anti-islanding. Who knows what sort of a load the external connection would present to your inverter if the grid went down and your inverter kept running, or tried to?

    actually I was referring to the fact that even though most if not all grid tie inverters have a built in anti-islanding feature many utility companies require a separate stand alone anti islanding system to be installed before they will allow you to grid tie. many of these practices were put into place before the implementation of 1741 and have simply never been updated
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    wild01 wrote: »
    actually I was referring to the fact that even though most if not all grid tie inverters have a built in anti-islanding feature many utility companies require a separate stand alone anti islanding system to be installed before they will allow you to grid tie. many of these practices were put into place before the implementation of 1741 and have simply never been updated
    Wow, I have never seen that. I assume you mean something other than the standard accessible, lockable manual AC disconnect?
  • GreenerPowerGreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>

    Gil,

    Here are my experiences in hot & humid Houston, probably very similar to yours.

    Umteen years ago I put radiant barrier (bought on eBay, aluminum foil backed with mylar, stapled under roof rafters). It dropped the attic temp down tremendously. A few years ago the roof was replaced and I've got radiant barrier roof decking at no additional cost. Now the attic temp is around 115F on a 95F day.

    I put in the battery backed up system (Outback) for outages during storms and hurricanes (helpful during Rita and Ike). Solar was added much later just to take advantage of the recent low PV price and to take federal tax rebates (and for fun to learn about it). I have 2 14000 BTU portable AC units to ride through outages in hot summer. Battery would last 2 hrs for our normal electricity usage and then the generator would be in order and to charge battery to get us overnight without the noisy gen.

    Hi SEER AC units don't work well in our humid climate - they don't take much moisture out. I wire a humidistat into my AC system to have a lower fan speed if the humidity is higher than some set-point to squeeze moisture out. Getting the humidity in the house around 50% or lower would allow you to raise the thermostat temp up and still feel very cool. That would save AC run time.

    So, for the money, put them in insulation, keeping house envelop tight. Look like you've done a lot on these. If you're DIY type, maybe radiant barrier sheet stapled to the roof rafters. I agree with other posters here that for area with grid, solar is not an economic solution. And if you must go with solar, grid-tie would give better return than off-grid. But depending on the city, the process to get grid-tie system inspected/approve might be challenging.

    Good luck in your decision.

    GP
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>

    I agree with other posters here that for area with grid, solar is not an economic solution. And if you must go with solar, grid-tie would give better return than off-grid. But depending on the city, the process to get grid-tie system inspected/approve might be challenging.
    Just to be clear, what we have said is that for areas with grid, off-grid solar is generally not an economic solution. Grid tied may or may not be economically feasible, depending on electric rates, available rebates, design of system, etc. As to the process for getting approvals and inspections; the integrator/installer usually takes care of that.
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: This SOLAR PLAN MUST be Possible>>
    Hi SEER AC units don't work well in our humid climate - they don't take much moisture out. I wire a humidistat into my AC system to have a lower fan speed if the humidity is higher than some set-point to squeeze moisture out. Getting the humidity in the house around 50% or lower would allow you to raise the thermostat temp up and still feel very cool. That would save AC run time.
    There's nothing special about high SEER AC units being worse than low SEER AC units at removing moisture. If it's not removing enough moisture that's likely a setup problem where you've got too much AC so AC cycle times are not long enough to remove the moisture (your AC unit is too big).
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