Solar Power for Florida Island

1 Posts
Jun 9, 2009 10:22 pm
Solar Power for Florida Island

Folks,
I have an island on central FL gulf coast w/ no access to utilities.  I'm building a small (1,200 sq ft) stilt house currently planned to be 40 X 30 w/ long axis oriented east west. There will be just two roof sections, one facing south, one north.  I really have three basic questions:  1) Can I get enough solar power to run the house, excluding AC/heat, by installing panels on the south-facing roof section and batteries to store the power? 2) Any idea what I should pay for the materials and installation of something like this?, and 3) Can you recommend reputable folks in central Florida that can provide the guidance and  service I need?  Many thanks to you all for your help.

Sincerely,
George Foster
Brooksville, FL
 
28 Posts
Jun 10, 2009 01:12 pm
Re: Solar Power for Florida Island

HomePower magazine had an article on similiar installation in Florida several years ago that would answer all your questions. I think it was a higher end home but should be applicable to you. I believe that they had everything on solar except the HVAC. You can pick up a CD of their first hundred issues for around $50 or I think you can subscribe to the website and search back issues.
 
Jun 10, 2009 08:57 pm
Re: Solar Power for Florida Island

So roughly you'll have a roof area on the south side pitch of 15' x 40' depending on the amount of pitch obviously for a total of 600 sq. ft..
I'll just pick a brand name PV module out of the hat,
Kyocera KC130TM, it measures 25.7 x 56.1 inches.
thats 8 modules long ways east to west and 7 modules eave to ridge for a total of 56 modules or 14 sets of 4 wired in series for 48 volts nominal for a total of 7,289 watt PV array. If the array is tilted south at latitude and we multiply that by the equivalent number of hours of full rated power per day, averaged out over a year, expected in Florida...
5 times 7,260 equals 36,400 or 36.4 kWhs or kiloWatthours.
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook/atlas/serve.cgi

Is that enough?

Think about it this way, if someone is paying the power utilities $100 per month and they are paying $0.10 per kWh that means they are using about 1,000 kWhs per month or divided by 30 that would be 33.3 kWhs per day.

The 56 KC130TM's could cost as much as $10,200.00 per pallet of 20. 3 pallets of 20 of course would be $60,600.00 might as well get the other 4 right?

Keep in mind now, that this is the most you could put of, this particular PV module, on one side of that roof.

The best practice is to figure up what your expected power usage will be in a 24 hour day first and go from there. Be liberal. Try to think of everything. You may what to round everything up and plan for expansion in the future.

I lived off grid for more than 20 years (no electricity at all) before utilizing a 1,000 watt PV array 10 years ago. Its plenty for the 4, sometimes 5, of us but then we were not pre-conditioned into believing the lie that the human race needs electricity in order to survive on the planet Earth. Benjamin Franklin didn't utilize electricity, he lived to be what, 80 something and look at what he accomplished in his life time. Not that I am comparing myself to him, mind you. I am just an electrician. He is the only American to have his signature on the three major documents pertaining to America becoming a nation in its own right.� 

Lets us hear back from you.

« Last Edit: Jun 10, 2009 09:04 pm by Thomas Allen Schmidt »
 
9 Posts
Jun 12, 2009 08:38 am
Re: Solar Power for Florida Island


The 56 KC130TM's could cost as much as $10,200.00 per pallet of 20. 3 pallets of 20 of course would be $60,600.00 might as well get the other 4 right?




Dude....check your math.  3 pallets of 20 would be $30,600 based on $10,200 per pallet of 20.

 
Jun 12, 2009 04:40 pm
Re: Solar Power for Florida Island

Muchas gracias Senor Friedman.
Indeed, $30,600.00 it is!
I am glad it was just that and not something less obvious.
I hope that $30,000.00 mistake didn't scare you away Mr. Foster.
While I am here i might as well figure up the battery bank. Again I'll pick a name brand battery out of the proverbial hat. Surrette's S-530 Rolls - 6 volt - 400 amp hours. It would take 8 of these wired in series to make one 48 volt nominal battery at 400 amp hours. If we go back to that figure of 36.4 kWhs of solar power from before and divide that by 48 volts nominal that would be 759.25 amp hours.

This is where you really need to know what your expected power needs are going to be first but I'll put that aside for now.

I like to multiply the battery capacity by a factor of at least 5. This helps to keep the battery state of charge in the top 20% of full charge, it can give you several days of power without sunshine, and it helps to prolong the over all life of the battery. So, using how much power would be produced by that PV array and assuming that is what will be used in a 24 hour period, 759.25 times 5 equals 3796.25 amp hours or if we divide that by 400 that would be 80 of those s 530's at $350.00 each or $28,000.00 by the way shipping is free east of the Mississippi on orders over 1,000 pounds which subsequently 80 of them would weigh 10,400 pounds.

I hope you can begin to see why its better to calculate the anticipated power needs first and how that could affect the overall cost of a system. It makes that second microwave oven a little less important if you catch my drift. How difficult is it to obtain propane gas at this island?
Hot water could be solar but then there is cooking and refrigeration to consider. Refrigeration can be electric as well, there are a lot of "off grid" refrigerator/freezers to choose from. I bit the bullet and went ahead and got an EZ Freeze 19 cubic foot R/F. Ours using no more LP than a Servel 8 cubic R/F despite what the advertisements say. Of course I enclosed it in a way that the back of it is isolated from the interior of the house and cut a hole in the floor, put screen over the hole, made a hole in the ceiling and a chase from there to the bottom of the roof, and then one of those turbine roof ventilators over top of the chase. If I don't block the hole in the floor in the winter time it works too good.

If I could make a suggestion? Start small with your PV array maybe 2,000 watt (it can be added onto later) but large with the battery bank and pure sine wave inverter(s) assuming you want 120 or 120/240 vac, if so, wire your house for vac like any other conventional house but don't use any multiwire branch circuits (sharing of neutrals) inverter manufactures warn against this, consider all of your appliances carefully, an 8 cubic foot R/F cost less but years from now you might wish you had gotten the bigger one. Living on an island I imagine a trip to the grocery store isn't a short one.

Man! I could go on and on with this but I'll let you absorb this and wait for a reply.

http://www.solarbuzz.com/companylistings/unitedstates.htm
 
Jun 13, 2009 05:47 am
Re: Solar Power for Florida Island

[quote author=Thomas Allen Schmidt
 If the array is tilted south at latitude and we multiply that by the equivalent number of hours of full rated power per day, averaged out over a year, expected in Florida...
[/quote]

I said that wrong. It should be - The number of hours of equivalent full rated charge.

As you may allready know, a PV module does not make full rated power the whole day. Its proportional. So the amount of power it does produce in a day is added up and divided by its full rated output. Hence the phrase - the number of hours of equivalent full rated charge (or power.)


http://photovoltaics.sandia.gov/
http://www.nfpa.org
One item that I cannot put enough importance on, that is a must have on a systems such as these is lightning strike protection. Charge controller(s), inverter(s), battery monitor(s) all utilized electronics and even nearby lightning strikes can cause damage to these items.
http://www.deltala.com/
 
Also, PV arrays mounted on dwellings must have GFP Ground Fault Protection on the PV source circuit(s).
http://www.iaei.org/magazine/?p=790

One other thing, have you given any thought to fire suppression? Obviously being on an island there would be enough water but if a house fire were to happen, God forbid, would you have the means to move a large enough volume of water to fight it?
http://www.jmefireequipment.com/
 

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