Undergrad Research Student in need of some Solar guidance

[Duggan419]

I have been trying to contact solar panel manufaturing companies directly, and they have been giving me the run around.  So I have stumbled upon this site and it looks like exactly what I've been looking for, knowledgeable people.

I am doing a research project on using completley renewable resources to power the FEMA trailers.  They are now powered almost entirely by propane, which has proven to be dangerous to the displaced families.  I have researched exstensivley to find the most efficient appliances to install in these trailers and have found the combined wattage to be 6,135watts.  

Products found and wattage:

 Fridgidaire Window Air Conditioner (150 sq. ft)= 515watts

 Maytag Electric Oven = 3500watts

 6 gallon water heater= 1500watts

 8 CFL (compound florecent light) light bulbs= 120watts

 Kenmore Refridgerator w/ top freezer (14.8 cu ft) = 400watts

I am choosing a trailer with dimensions of  27.0' x 8.0'.  

Would this trailer be feasible to run on solar energy alone?  Is there enough space on the roof for the neccesary amount of panels? Will the gulf coast climate be sufficient for supplying enough sunlight?

I have so many more questions but this is just a start.  Thanks for you help!

Air Conditioning on PV? Surely you jest?

Intro text fixed to fit the character limit, also. TW

[DanB]

Yes, its really quite of the question to run electric stoves, ovens, air conditioners off solar at todays prices (or even a fraction of todays prices).  Possible... but very very expensive!

A good book on wind/solar power basics which would answer a lot of questions for you and its a fun read:  Power With Nature by Rex Ewing

[asheets]

They are now powered almost entirely by propane, which has proven to be dangerous to the displaced families.

The college professor in me would demand that you properly document the above statement -- mainly because the board participant and the man who lived most of his younger years on propane (before he became a college professor) would heartedly disagree.

Off the top of my head, I'd say you just barely have enough space on the roof to supplement (not replace outright) the hot water heater with non-PV solar panels.  A google-search of the board might give you some additional ideas on how to reduce the power usage of the a chest freezer so that it can be used as a fridge, and MAYBE you could run that on a slew of PVs.  But then you've got to consider initial costs -- propane can be set up quickly, cheaply, and flexibly (not to mention, safely).  Solar is expensive, and when you consider the batteries you'll need for many of the applications you describe, definitely not flexible or quick either.  And, if you aren't careful, running that oven off the solar-charged batteries could potentially cause an explosion hazard that'll parallel propane any day.

Do some reading and see what various people have come up with.  Personally, I'd steer you toward some of the at-sea and yacht-owning members of the board who use combo solar/wind solutions.

[ghurd]

"Would this trailer be feasible to run on solar energy alone?"

Sure.  If the trailers are full of money.

"Is there enough space on the roof for the neccesary amount of panels?"

Not even close.

I get about 32, 75W SolarWorld mono PVs.  2400 rated watts.  Under 2000 real watts.

So 2KW x 5 hours?  10KW.  Then losses... etc.

The A/C can run 2/3rd of the time, with luck.

Maybe the oven for a couple pizzas.

But not both.

Probably the fridge and lights.  Maybe a little A/C.  No oven.  No hot H2O.

No mention of TV or DVD or sat box or PC or fans or cordless phone / cell phone / iPod / razor charging.

Think battery.  Gonna jack those things up to 2-stories to hold enough batteries?

You need to find a 'solar sizing worksheet'.  

That will tell how many watt-hours it needs.  Then solar insolation charts to find out how the PVs will produce.  They should figure the battery size too.  Then how many of the chosen PVs.  Then the dimentions.

Then the stuff in between. Controllers. Disconnects. Boxes. Mounts. Inverters. Wire.

Then price the system.

Then add labor and maintainance.

(I would be curious to see what it comes out to)

Propane is dangerous?  More safety stuff than most anyone can screw up without doing it on purpose.  Idiot Proof.

Try DC power and battery acid.

And who is going to fund this?

Not Them?  Meaning Me?  Again?

Would be a nice paper, but I pray it never actually gets done.

G-

[DamonHD]

Here's something I did about the (roof)space and cost to get a whole small (London) house off the gas and electricity grids.  Scaled down a little it might be trailer-sized...

http://www.earth.org.uk/towards-a-LZC-home.html

Rgds

Damon

[Duggan419]

What about creating a network of large solar panels?  These FEMA trailers are usually in large communities.  So what if the community as a whole all had solar panels covering the top of each trailer.  The power would be used as needed, and then unused energy stored in a shared battery storage unit of some sort.  Just as a starting point...say 50 trailers with dimensions of 27' x 8'.  

And I'm beginning research on wind power like you advised, I will let you know how that goes.  Thanks for you help thus far.

[spinningmagnets]

I have speculated that, someday when I retire, I might purchase a property with no home on it. This is the reason I'm now doing my homework here.

Rather than "waste" money on a trailer home while a proper "passive solar" house is built, I have contemplated various temporary housing options that will still be useful later for storage or a shop.

I have seen two of the steel shipping containers (8 feet wide, 10 tall, 40 long) set parallel with an elevated shade roof over both. The area in-between formed a shaded patio of sorts. The elevated roof shaded the walls and tops of the containers, so even on a hot day, the interior temps were mild.

A glance at your figures shows that a federal employee specified the details. An evacuee yard will most likely be set up in the nearest vacant field, and immediately supplied with electricity by mobile Diesel generators (later changed to propane?). Trailers of some description will be brought in to form a temporary community. Port-a-johns can be set up, a 5,000 gallon water truck can be parked, and a satellite dish with a portable cell tower set up. Laundry can be done in a "laundromat" trailer.

Then, people will "want" certain things, but sometimes teenagers and evacuees shouldn't be given everything they ask for.

To heat up the inside of a trailer in hot weather with a 3500 Watt electric stove, and then to cool it with air conditioning is,...well...the type of thing the US government would do. This is not a good idea, and it eliminates the possibility that renewable energy might be used. The electrical loads are way too much, and the size of battery needed (cloudy day, no wind) is very large. Evacuees cannot be expected to  properly care for a large expensive battery pack.

Trailers should be provided with an OUTDOOR propane barbeque under the patio shade (no carbon monoxide build up). The insides should be provided with cross-flow windows and ceiling fans. No AC, an elevated roof can be deployed to shade the top and the sunny side. Refrigerators should be chest style. If the weathers too rainy to cook outside, eat sandwiches (I do) or stew from a low-watt crock pot/e-skillet/microwave. Use low-flow showers with a small propane water-heater tank and solar water pre-heater. (Don't like the set-up? we can help you get a job in a state where there's work, and then you can pick your own apartment)

If you want to put solar PV panels on the roof and a telescoping windmill, great, they will charge a battery pack. An inverter will alow the battery to power some lights and TV at night.

For the amount of money FEMA has spent on each family to rent a hotel room for 9 months, they could have given them a car, a motor home, and a piece of property where there are jobs nearby. The trailers FEMA built had brand new carpet that strongly smelled of formaldehyde, making some people sick (why did they need carpeting?).

There are lots of retired snowbirds here now in Southern Utah (from Montana, Idaho, etc). They live in small motor homes or fifth wheel trailers. They cook with propane and have propane back-up generators. Their electrical loads and battery packs are small. They seem to be much happier than the evacuees I've seen in on TV.

The scariest words in the english language are "I'm from the government, and I'm here to help you" -Ronald Reagan

[ghurd]

OK.  Sure.  10% are occupied.  The other 90% are full of $102 bills and batteries.

Communities of FEMA trailers have people in most of them?

The people in the OTHER trailers don't want A/C, hot water, stove, TV...

You really need to do a worksheet and the other stuff I mentioned.

Maybe do it for just the stove.  Maybe only the A/C.  The hot H2O for a family of 5.

Then you will understand.

The nice thing about wind?

When the next hurricane comes... the batteries will be fully charged to run the pumps.

[richhagen]

Hmm, very briefly, and not my most organized response, but I think a more reasonable way of looking at your problem would be:  What can be powered with an RE-only trailer to maximize its standard of living.  

Since the FEMA trailers are used in emergency situations, I would look at what is necessary to power in order to sustain life first, and increase the productivity of the occupants second.  I think that once you investigate your options, you will find that it is not reasonably possible to maintain every luxury appliance and feature that we take for granted in the U.S. in this type of situation.  I would try to simplify my goals to keeping people alive and functional.  

For some people, air conditioning may be a necesity for medical reasons, but for most, even in the gulf, air conditioning is a luxury.  Based upon the relative power consumption, I would recommend air circulation as opposed to air conditioning for the purpose of limiting the maximum temperature.  

Hot water for sanitation is probably beneficial.  Refrigeration is probably beneficial for food storage.  

You will also want some AC power from and inverter for small AC appliances from the occupants, such as cell phone chargers, other comunication equipment, or other items that may enable them to function more efficiently in the aftermath of whatever disaster caused the trailer to be in use.  This discretionary type of electrical usage would have to be limited however.

For air circulation, a built in ducted fan with limited power draw selected for its efficiency and reliability.  Also I would place the solar panels on a tiltable rack so that they could be adjusted at least for the latitude and season where the trailer is in use.  This should shade at least part of the roof from the direct sun which should help a bit too.  

For hot water, I would use a solar thermal system rather than an electric hot water tank, as the solar thermal system will be both cheaper and make more efficient use of your limited roof space.  

Compact flourescents for the lights.  LED lighting might be an option as well, if not now, in the near future, as it is becoming, and has the potential to become much more efficient.  

Many of the persons using these trailers will have limited knowlege about how such systems work.  You will have to design the system to prevent someone from bringing in a 2000 watt appliance and leaving it connected all day using up all of the available power.  Failsafe and Foolproof so that even the most uneducated can get some benefit from it.  From experience, you will find that you will not be able to rely on training to overcome these issues.    

[DanG]

Replacing the copper propane lines with something unattractive to thieves & other vermin would be one good safety step.

Going with passive conservation measures has the highest payoff:

Super-insulated trailers, reflective roof coatings.

Quality double pane windows with coated glass.

Window awnings to shade interior from summer sunshine.

Entry cubicle or porch to lessen air exchange from entry traffic.

Timer on hot water heater & set back thermostat.

Halogen light browning microwave oven.

Thermo-siphon solar water heater tempering tank.

If you place photovoltaic panels on the trailers a large percentage will be stolen.

[wooferhound]

For sure you would want to use microwave ovens instead of a stove

[Volvo farmer]

"Would this trailer be feasible to run on solar energy alone?"

Sure.  If the trailers are full of money.

Curse you ghurd! Perfectly good beer blown out of nostrils! Damn it burns!

[finnsawyer]

I would add the question to the propane issue, "Are the users stupid or are the designers of the trailers stupid?"  In either case design the trailers so that the propane tanks are not accessible without a key kept by the propane provider.  If the occupants are illegal aliens send them packing and save the money.

[stephent]

So who is going to do PM on the trailer batteries for the sometimes 2 or 3 years of just sitting in a yard unused? (I would love to be the battery supplier for this!).

And hookup and clean the solar panels when deployed?

Who is going to fix the electrical dodads when they break?

Who is going to test the whole sheebang each few months just to make sure stuff works still? They --well "shouldn't be"--stored for years neglected.

Would you allow Govt contract suppliers to haul YOUR PV bank around?

The propane would probably just sit there and wait patiently until needed.

A solar water pre-heater would probably be an asset, but the plumbing might be slightly fragile for a disaster area...a small set of PV panels for just a couple lights "might" be beneficial but costly in the long run.

You ever been around a storm/hurricane disaster housing area? The buildings need to be solid concrete and bulletproof. Even the relief and re-construction crews housed early in these things are heavy handed sometimes.

 

[elvin1949]

V F

 What came out of my nose was a tad bit stronger than beer.

later

Elvin

[richhagen]

Of course, knowing us, after years of research and millions of dollars spent, we'll build a fairly decent trailer for the gulf after a hurricane, well ventilated, solar hot water and such, and then the next disaster will be in Minnesota in the dead of winter where we will try and use them and they won't work right.  Rich

[ghurd]

Maybe they will have non-corroding (solid gold) gutters and down spouts.

Always useful after an earth quake in death valley.  ROFL

G-

[Volvo farmer]

You were drinking from the left hand, I was drinking from the right. It's all in the timing really :-)

[spinningmagnets]

The military has Containerized Living Units (CLU). Using standard steel shipping containers, they can be deployed by cargo planes, helicopters, or trucks. (Container trucks pick-up and drop like a flatbed roll-off tow truck). They are robust and shrapnel-resistant (hurricane?), but not luxurious.

http://www.combatreform2.com/isopowerunit.jpg

[finnsawyer]

The son of a friend of mine was in the SeaBee reserves.  Once they were ordered to demolish some temporary housing to make way for permanent structures.  They noticed some locals living in shacks outside the base and asked them if they would like the trailers.  So, they moved them outside and connected up the services rather than destroying them.  I think those boys deserve a salute.  It's that kind of independent thinking that has always being the strength of our armed forces and our nation.

[finnsawyer]

They'd work fine in Minnesota if they are insulated well, but maybe not here.  Here, their flat roofs might collapse under the weight of the accumulating snow.  On the other hand no one has ever come to our aid no matter what disasters we've had here.

[spinningmagnets]

My brother was a SeeBee at Port "Who-needs-me" in Pt Mugu. We should be building quick deployable robust trailers with minimal luxuries. There should be several storage yards within a days drive of anywhere in the US. There will be earthquakes, floods, tornadoes, huge brush fires, etc. Only question is when and where.

When I worked in the desert for a road-building company, we ate in a cafeteria trailer, showered in a shower trailer, and slept in four-bed single wide trailers. They turned on the A/C at bed time powered by a diesel generator on...a trailer. (no TV or music unless you brought it)

The most watts per square-foot PV panels are (of course) the most expensive. If you "want" to power high loads with fixed size of array, you could spec these. Tracking mounts would add over 20% more watts (I've heard). High winds rarely occur when its sunny, hail and flying branches always happen during high winds, therefore, high winds should activate a "face down" retraction. During high winds the wind-gens should be able to keep up...either that or evacuees will have to do without TV a few nights.

Battery packs can be stored without electrolyte until deployed (then auctioned after a few months use when the emergency is over). Each trailers battery pack should be accessible from the outside so they can be easily maintained by trained personnel.

For cold camps, the propane furnaces can be small, and located outside, so the furnace cold intake air and exhaust can never be mixed with the warm inside air. The propane flow (no pump required) can spin an internal magnetic rotor in a non-magnetic housing. This housing can be attached next to part of the heat exchanger loop (two tubes going into the trailer wall, in/out). In this way, the flow of propane going into the small furnace will power a small fan inside the heat exchanger loop with no mechanical connection or seals to leak. If the trailers cold tube is near the floor and the warm air tube is near the top, there will be some natural thermosiphon flow as well (hot air rises).

I can't imagine the US government using large format NiCD's or NiMH's, but I can see them using Lead/acid or Lithium (LiFePO4, not the "bad" lithium's). If you specify a format of 12 volts about the size of a motorcycle battery, you won't have any problem auctioning them off to the EV folks after they've been used a while.

[elvin1949]

 You are right.I was drinking with the left hand.

later

Elvin

[Duggan419]

Okay here is the update on where I am.  I now have a trailer that runs on 4.1kilowatt-hrs per day.  I then performed a battery sizing calculation with this website:

http://www.howstuffworks.com/framed.htm?parent=question418.htm&url=http://www.sunelco.com/

I used a Crown 395 AH 6-volt Deep Cycle Battery...and found out I was going to need 28 batteries...Obviously not acceptable.  So then I neglected cost (and weight) and found a 24 volts 935 amp-hour battery....and I would still need 4 of these giants to run the system.

I have the most efficient of every appliance (CFL lighting, 2 cieling fans, microwave, refridgerator and window AC) but it still looks like an impossible feat to power these trailers on only renewable energy.  I think that my professor just gave me this task to prove that propane and diesel generators are the cheaper and more reliable choice.  Does anyone out there have suggestions for how to make this work?? And don't worry about price....just go for broke because then it will make a more reasonable case to my prof on why this plan just isn't feasible.  THANKS!

[ghurd]

Why is it NOT feasable?  Other than cost?

Idiots. Soorry- 'End User'. (you didn't get the basics of cost- but they should understand how it works???)  

Sleeping with the TV and 4 lights on is no big deal?

Looks like water, so it won't make a scar on my legs (like mine)?

Volume.  Trucks were lined up to get into N.O.  From the Red Cross, GB, a guy from Akron OH who made the local paper, and almost everybody else.

The Mayor refused them entry, in an attempt to make people flee.  Good idea IMHO, but don't blame the RC and GW for not sending help after the fact.

If FOOD can't get in, how many pre-fab homes with solar, support system, and batteries can get in?

Do those things come with TVs?  Just curious.

Cost of system storage.  They cost a LOT.

Batteries only last so long, even if they were never used.

Mobility.  

Move a bunch of wet batteries.  They are dangerous and heavy.

Move a bunch of PVs.  They break. Often.  Ask UPS.

Reusable.  

Connect a bunch of PVs, remove them, reinstall them.  Some Butt-Head broke half the important parts.  Nobody at-hand understands how to fix what can be fixed.

Put a good controller in, then out, then in.  Somebody sometime did a bad thing, and it's shot too.

Ditto for the inverter.

Batteries, in a reusable fashion, wear out from standing wet.  They don't last all that long either, even under good conditions.  Batteries deployed at the start would be long ago recycled.  Meaning more supplies and costs.

Takes a while to connect it.  

Wires. Poles. Pipes. Batteries. Grounding rods, if you are so inclined.

Who is going to that?

A system that size with Gov't funding should have a tracking system (it is the best bang for the buck on something that size).  Who will take care of that stuff?

And the top 10 reason....

Who will make sure the PVs point south.

Funny.  In a strange sort of way.

G-

[Duggan419]

I now and have an estimate of 5192 watt-hours a day needed for basic neccesities on the trailer.  Using a 200watt solar panel with dimensions of 39"x56.2" on my 8'x35' trailer I can fit 14 solar panels. Is this calculation shown below right for the daily wattage the panels will provide?

(14 panel) x (5 hrs avg peak sunlight) x (200 Watt) x (95% efficiency of the panel)

= 13,300 watts per day

(I'm just ignoring, for now, that all the panels cost a total of $12,152)

If this is wrong how do i effectively judge the amount of watts a solar panel will provide per day?  I need to know this so I can start justifying the need for a wind turbine along with the solar set-up.  Thanks for your help.

[DamonHD]

My entire house and family and home office in London comes in at almost exactly 7kWh/day, so my feeling is that your figure is too high still.

For example, if I was not running my Internet-facing server that would drop 1.1kWh/day.

If we replaced our ageing fridge/freezer with a new efficient one that would save maybe another 1.2kWh/day.

I'd already be below your figure for a trailer.

Rgds

Damon

[TomW]

419;

= 13,300 watts per day

Where did your time factor go?

This [common] mistake causes confusion amongst the new folks.

Lets be accurate when stating energy and power units.

Cheers.

TomW

[ghurd]

First...  Thanks for checking back in!

It often feels like a waste of time answering.

The 5 hour thing seems WAY off.

Hurricane Katrina?  What was the average insolation for the next 90 days?

That was about as far south as you can get.

The 95% thing is way off too.

It will need MPPT (google it) to get close for one thing.  Batteries are not 95% efficient either (IIRC 90% is best case).

Wire losses.  Semiconductor losses.  Hot PVs in any area with 5 solar hours a day.

Take the 95% back to 60%?

What if the insolation is based on an average?  (and it is)

What if the insolation average is 10 days with 0 sun, the 1 day with full sun?

In that case the battery will reach regulation voltage in a short time.

The rest of the day's sun will NOT be put into the battery.

(see link)

Wind power is much the same. 10 days with 0 wind and 1 really windy day.(see link again)

How did the wind after Hurricane Katrina compare to average?

Wind power takes a lot of planning. Towers for one.

A user that comprehends the system for #2.

TALL towers, LONG wires, HIGH voltages, NO morons.

After reading the link...

How much battery will it take to maintain this system?

How much generator/fuel/wiring will it take to make sure the starving masses have everything they desire, if the wind ain't blowin' and the sun ain't shinin'?

That is a lot of battery.

Here, with solar the way I figure solar, 5200WH/D, divided by 1.5 = 3500W.  And 3500/17x12= 5KW of PVs.  I would kick in an extra 20% for reliability.

The link,

http://www.fieldlines.com/story/2007/4/28/232143/114

Your rated solar panel array just went to 6KW.

Not PC.

People die.  Just like rabbits.  When its too hot or too cold.

More people die when it's cold, or the population line wouldn't be along the equator.

People die when they have heat and A/C. It happens.

People die.

Should someone in 'Hurricane Katrina' without A/C get RE A/C,

before my parents get RE heat?

My parents plan for this kind of thing (and they taught me to do it too).

Crazy stuff, like cut fire wood before January.  Know how to get drinking water out of a water heater.

Know how to kill and cook local fauna.

Lots of other trivial stuff too.

Maybe folks in places like where the gov't says "GET OUT While you still can!" should get out then (like my folks taught me).  Then they could come back to their solar panels.

[Duggan419]

I apologize...i meant to write 13,300 watt hours per day

[TomW]

Duggan419;

No need to apologize. It just is a point of confusion and we are trying to keep things clear. Thanks for the clarification.

Cheers.

TomW

[Duggan419]

Lots of info to process, thank you for your help.

What are the numbers you have for your calculation of the solar panels appropriate KW of PV.  Why are you diving by 1.5? What is the diving by 17 then multiplying by 12?  So could you please just break down what you actually did, remember I'm a newbie at this.

[Duggan419]

I looked for the best battery sizing chart and found this:

http://www.wholesalesolar.com/battery_sizing.html

So I did a battery sizing with these specs: (All for Gulf coast region)

5200. watt-hours per day
      
4. 5 avg. consectutive cloudy days
   
   

Used both 50% and 80% battery discharge

Low temp factor of 1.19 with avg low of 50F

Watt-Hour Battery Capacity~(395AH)X(6Volts)=2370 (Crown brand battery)

With 50% discharge: (28 batteries) x ($300.45) = $8412.60

With 80% discharge: (16 batteries) x ($300.45) = $4807.00

Is that unreasonable amount of batteries? Dimensions are (11.625" x 7.0" x 16.125") So they could be stored under the trailer.  

Thanks for the MPPT recomendation...it will help in the efficiency calculation for the solar panels...

And I JUST got an email from my prof saying that a grid tie in could be a possibility for the design but to limit its usage....hmmm changes things a bit....the tie-in would allow for hot water...which I still hadn't added and possibley even a reduction in the amount of batteries...lost of new variables to deal with now....