# Portable Solar 'Generator'

Registered Users Posts: 7
I am wondering if some here could assist in helping me build a portable solar 'generator' ... something that I could use between 1 and 3 solar panels depending on available space, and then having 110VAC outlets to plug items into.
For example, in a power outage, I could run my refrigerator to this generator, or a computer, or even television.

I know I'll need the panels but there are some with the charge controllers built in and other that do not have that option.
1 or 2 batteries in some sort of case I can put on wheels, and then some sized inverter.

Additionally, I'd like to use this as a 'test rig' to see if I can run my 220VAC submersible well pump from it and how long a charge would last in doing that. I'd need some sort of step-up transformer for that as well.

Thanks.

JHR,

A portable solar generator really would not support more than a laptop computer and a few lights. In general, running a refrigerator for a "useful" amount of time and 220 VAC well pump--A generator running from gasoline, diesel, natural gas, propane, etc. is really the only practical solution.

Say you could run 3x 140 Watt solar panels (reasonable size to move around/store by one person). Assume 4 hours of sun per day (typical ~9 months of the year minimum for a reasonably sunny location):
• 3x 140 Watt panels * 0.52 typical off grid AC system efficiency * 4 hours of sun per day = 873 Watt*Hours per day
A typical, very efficient full size refrigerator+freezer is around 1,000 to 1,200 Watt*Hours per day.

And a reasonable size battery bank would be 1-3 days of storage with 50% maximum discharge (flooded cell lead acid type). So for a 12 volt system:
• 873 Watt*Hours per day * 1/0.85 AC inverter eff * 1/12 volt battery bank * 2 days storage * 1/0.50 maximum discharge = 171 AH @ 12 volt battery bank
Or roughly 2x 6 volt @ 200 AH "golf cart" type lead acid batteries.

The above system would be recommended to output ~ 5 hours per night (or 5 hours of cloudy weather) for 2 days and 50% maximum discharge:
• 2 * 6 volt * 200 AH * 0.85 * 1/20 hour discharge rate = 102 Watts recommended "average" 100 Watt load for 2 days of backup power
If you where going to run a large load (like a well pump), the maximum load I would suggest would be:
• 2 * 6 volt * 200 AH * 0.85 * 1/5 hour discharge rate = 408 Watt maximum load (for minutes to an hour per day)
That well pump would probably take something like 1.5 to 2 kWatts minimum to run. No way for a small/portable solar power system to run a standard utility fed well pump.

Does that mean the portable power system is no good? No, it just means you have to either re-think your loads, or design a larger system, or use the small system for laptop, LED TV, cell phone charger, a few LED lights instead. And get a 3.5 kWatt (or possible larger) genset to run the well pump and possible the refrigerator/freezer.

A really helpful tool for you to understand your smaller household loads is a Kill-a-Watt type power meter. It will give you enough information to understand your loads, decide if you can conserve power with a new appliance (if nothing else, reduce your utility bill) and decide what are your critical loads that you plan to run if you have a 1-3 week power outage.

More or less, for most people, this is going to be a lot more like camping than living a full power/normal life--Unless you can install and fuel a genset (stored fuel, natural gas) for those several weeks.

A large enough solar+battery back power system to run even a drastically reduced load set (say ~3.3 kWHours per day)--You are still looking at a \$10,000 to \$20,000 solar power system. Usually way too much for a short term emergency power system. A genset plus stored fuel (and/or natural gas connection) is cheaper both in the short and long run (batteries need to be replaced every 5-8 year and inverters / charge controllers need to be replaced every ~10+ years, etc.).

If you are looking at mulit-month power failures or simply cannot live without backup power--Solar+Genset may be a solution... But understand your loads and do a few paper designs first (including cost to build/install) and see what they are worth to you.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Registered Users Posts: 7
Didn't realize it took that much.
OK . . . I am sure I can handle the larger panels, say the 220watt or so panels as I would build a cart on wheels that I could move them and set them up on. I have also already changed most of our house bulbs to LED bulbs. I will have to rethink the refrigerator and well portions.

So, I'd still like to build the 3 panel generator style system for a few lights, laptop and LED TV (and even alarm system in our home). I am wondering how this works, however, if the batteries are fully charged and not used/discharge for some lengthly period of time, 2 weeks,2 months, etc.?

Also, my main worry is the possibility of some sort of long-term electricity loss, be it from a sun discharge or even an EMP strike ... other than an LP generator which certainly would work for me, is there any good reasonable way to do the following with solar:

Run a well pump to ensure we can get water for indoor plumbing and to shower (I have to figure out how to get hot water as well for showers)

Being a 'prepper', the reason I don't want to run an LP generator is because in case of a very lengthy outage, a national emergency type, the noise of a running generator would make me a target out here in the country.

Thanks.

We can help, but we need something as a starting point:
1. your rough location (nearest major city so we can figure out the amount of sun)
2. you loads (Watt*Hours per day, any special voltages, high current loads, etc.)
3. OR the size of solar array you will use
4. OR the size of battery bank (voltage @ Amp*Hours, number of XYZ batteries, etc.)
5. OR the size of AC inverer
6. OR how much money you want to spend
Or similar... Basically #3 through #6 give you a system size (starting with our basic rules of thumbs) and a capability (Watt*Hours per day, maximum load size, etc.).

In general, conservation is going to be your friend. Running a chest freezer as a refrigerator in a basement is a lot better than a fancy in door water/ice refrigerator in a hot kitchen during the summer.

For emergency/backup power systems, generally minimal loads and minimal solar power system (keep costs low). Some folks will design a full off grid capable system and get a Hybrid AC inverter so you can use the Grid/Sell excess AC power back to the utility (if allowed/makes economic sense with your utility)...

Anything can be done, but if you are planning on 10 kWH per day (300 kWH per month), that is not a small solar power system--But yet is a pretty much a very efficient/lower power grid connected home. Most homes use around 600 to 1,000 kWH per month, and if you have AC/Electric Heat/Electric Hot Water/etc., it can run 1,000-3,000 kWH per month. Solar Power systems that can run homes with this level of power consumption could cost in the high \$XX,000 or even into the \$1XX,000 range.

Not trying to scare you from solar--But you really need to have a good idea of what is acceptable power usage for your off grid experience.

Personally, I would suggest a ~3.3 kWH per day is a pretty serviceable system (lights, well pump, laptop, clothes washer, reasonable well pump). Use other fuel sources for cooking/heating--Perhaps solar hot water/thermal collector would be a nice addition (solar thermal is a great DIY project for heating/hot water).

Is that reasonable to you? I don't know--Energy usage is a highly personal set of choices.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 626 ✭✭✭
Here is a thread I started last year.
http://forum.solar-electric.com/foru...ilt-frame-work
• Solar Expert Posts: 766 ✭✭✭✭
With a portable solar generator with out batteries you can forget about the well pump and pretty much forget about running the fridge.
If you add batteries you can run the fridge and other small items.
Problem is when you buy batteries they will go dead from sitting after a few years.
If you are a preper then you should have some kind of water tank or tanks. Get a generator, run it for a little while fill up water tanks and run other heavy loads, charge batteries and turn it off.

Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

• Solar Expert Posts: 766 ✭✭✭✭
Here is my entry level post apocalyptic generator setup.
http://forum.solar-electric.com/forum/solar-electric-power-wind-power-balance-of-system/off-grid-solar-battery-systems/25027-trailer-mounted-systems
I am the last post. It has about 100ft of cords strapped to it and 18 gallons of total fuel capacity, one AGM battery and a 1000watt pure sine wave inverter.
I figure I might add a solar panel and more battery capacity at some point.
The battery inverter keeps the generator off a lot of the time. It supports small loads like laptop, drill, small lights, fridge. But that one battery wont run a fridge for very long.

Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

• Solar Expert Posts: 626 ✭✭✭
Unless the OP gets into LiFePO4 a "portable solar generator" is out of the question for practical use.

From my experience the units are heavy using AGM deep cycle. My portable version weighed in at 160+ lbs. it wasn't practical for mobility for AVG people. (Me I'm not AVG 200LBs, 6'-2")

It was great for running appliances for brief moments, but long durations with a 120Ah, 12v battery is out of the question.

Solar generators are good for experiments, but that's about it. For survival if needed it will work minimally but solar can't compete with gasoline generators, where some 1000watt generators can use roughly 2gallons of fuel a day, for all day duration.

I have the money to invest in to experiments, infact one of my companies is just that for R&D, experimental for tax write offs, and patents.

I'm actually investing into LiFePO4 for a final generator solution. If I can't get it to work with lithium, it won't work for basic transport. What I do know from the compiled research so far, is that you cannot harvest enough Big Bang energy for basic transport.

Once we convert to 240/120v appliances the consumption rates for kWh becomes to great for transport, but is appliances stay on a DC 5v, and 12v platform it is some what reasonable.

I am devising a solution for portable solar generators to connect into a main service, when the grid is down so the grid tied solar can still operate, this would only work
If there is a main service breaker to shut off for isolation of islanding.
• Solar Expert Posts: 766 ✭✭✭✭
Here are my portable LiFePO4 power packs.
http://www.dieselplace.com/forum/63-gm-diesel-engines/21-6-5l-diesel-engine/444540-byob-more-power-lot-less-weight-7.html
Those 2 lithium packs are a good example of my military/industrial dystopia styling. If it looks like some of the elements those packs are made of is 3rd or 4th life, that's because it is. Only the lithium batteries and Anderson connecters are new.
The 40ah lithium battery needs an inverter installed. I am wanting to get another sweet deal on another pure sine inverter like I put on my generator for my largest Lithium battery.
I also have a jump starter pack with an AGM batt that has a 350 watt elcheap-o modified sine inverter attached to the back (not pictured).

A lot of people come on here looking for one big fixed (immovable) be all end all solution to all their power problems. Put all their eggs in one basket if you will.
I take the opposite approach. Lots of little, mobile decentralized solutions.

Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

• Solar Expert Posts: 626 ✭✭✭
For my LiFePO4 I've been looking into RC car battery packs. High discharge rate, high efficiency charge rate. Easy packs to splice for parallel 12V circuits. The charge controllers are cheap and easy to add solar to.
• Solar Expert Posts: 766 ✭✭✭✭
I had not considered LiFePO4 RC packs.
I really like the premade packs. After carefully spending hours preforming white knuckle battery surgery putting individual cells in series stacks of 4 then paralleling the fully charged stacks of lithium cells together, I have to say it sucks!
Spend the money let some one or some machine build up and seal up cell stacks for you.
Its almost like playing that game "operation", in this real life game of "battery operation" something really could go bad if you touch the wrong edge with a tool or the wrong edges touch together. (I hated "operation")
Putting together AMP20 prismatic cells isn't too bad if you have the proper cell tab connector plates.

Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

• Registered Users Posts: 4
I find this post interesting and somewhat inline with my thoughts minus the well pump and fridge. I do like the basement freezer vs. fridge upstairs in higher temps requiring more power. Great idea!
My interests are for a Portable Solar Generator that would allow for a multi port charging station that could handle twelve Tablets, Cell Phones, etc., a small LED TV, Dish Network Receiver, and Approx. 12 100w equivalent LED Bulbs. This system I would build with a Tow Behind trailer capable of handling the weight of all components and pulled with a ATV, Vehicle, etc. with a 1 7/8"-2" ball. It would be portable to be placed in the best collecting area with no shade concerns.
How many panels would this require at what wattage per panel? The system would be used both day and night although not at full capacity based on the items I would like to power, day time would exclude LED Bulbs, Most charging items such as Tablets etc. could be done during daylight, night use would be for Dish Network, LED Bulbs. How many batteries with the preference being AGM vs Lead Acid, what size inverter would be required and type to handle the items I would like to power? I am new but reading as much as I can, to learn as much as I can. Appreciate all replies. Hope this post is in line with the original Topic. If not please advise and we can move my post to proper area or thread. Thank you!
Tim,

I would suggest a kill a Watt type meter (see my first post in this thread).

It will be less confusing.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 626 ✭✭✭
Sonlight wrote: »
I find this post interesting and somewhat inline with my thoughts minus the well pump and fridge. I do like the basement freezer vs. fridge upstairs in higher temps requiring more power. Great idea!
My interests are for a Portable Solar Generator that would allow for a multi port charging station that could handle twelve Tablets, Cell Phones, etc., a small LED TV, Dish Network Receiver, and Approx. 12 100w equivalent LED Bulbs. This system I would build with a Tow Behind trailer capable of handling the weight of all components and pulled with a ATV, Vehicle, etc. with a 1 7/8"-2" ball. It would be portable to be placed in the best collecting area with no shade concerns.
How many panels would this require at what wattage per panel? The system would be used both day and night although not at full capacity based on the items I would like to power, day time would exclude LED Bulbs, Most charging items such as Tablets etc. could be done during daylight, night use would be for Dish Network, LED Bulbs. How many batteries with the preference being AGM vs Lead Acid, what size inverter would be required and type to handle the items I would like to power? I am new but reading as much as I can, to learn as much as I can. Appreciate all replies. Hope this post is in line with the original Topic. If not please advise and we can move my post to proper area or thread. Thank you!
If your intent is to build a 5th wheel tow "generator", for the items mentioned, you would require the following.
- 600Wp in mono crystalline. (Solar World 300/310/315 watt panels or LG 300 watt panels). Solar Worlds are better manufactured to handle transport abuse. LG's are slightly smaller, but have a better I-V response curve for lower light levels. Mono requires less angel of incidence compared to poly.
- Minimum 40amp MPPT controller
-(2) 120Ah AGM deep cycle batteries
-12v pure sine wave inverter 2000watt

(2) 300 watt panels are to be ran parallel into the MPPT controller to maximize harvest. This will require MC4 parallel splice connectors, and addition USE2 wire with mc4 pin and socket pigtails.
-6AWG conductor with an inline 40amp AGU fuse from controller to battery bank.
-(2) 12v batteries are to be installed parallel to maximize harvest. (Do not install in series for 24v)
- no more than 17" of 6AWG from battery bank to inverter, install 80amp AGU fuse inline.

Most mobile inverters for RV use come with the 5v USB ports.

6AWG is to be that of THHN rated at 90*C. All conductors , with the acceptation of USE2 wires are to be installed in shielded LMFC with the appropriate ground connectors from end to end, and all parts of the system to be chassis grounded.

Kindest Regards
• Registered Users Posts: 4
Hi Bill, Thank you for your reply. Okay, if I order the Kill-a-Watt I will need to plug in the items I plan to power. Should this be done individually to obtain my usage and how long would you suggest for each reading? I can easily plug the LED TV and Dish Receiver into the Kill-a-Watt to see what readings are obtained there. I would probably have to charge two tablets at near empty charge and multiply by six to come up with that usage for a 12 Charge Station and could do the same for the 100w LED bulbs for that usage, currently we are using Fluorescent Bulbs 100w = actual 23w usage. Thanks again!
• Solar Expert Posts: 626 ✭✭✭
Or if you don't want a kill-A-Watt take the name plate rating off the equipment and then multiply by how many hours you use that equipment.
Name plate ratings can be way off (usually too high). Is better to spend \$35 on a kill a kill a Watt type meter.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 626 ✭✭✭
BB. wrote: »
Name plate ratings can be way off (usually too high). Is better to spend \$35 on a kill a kill a Watt type meter.

-Bill
Agreed the name plate numbers are the maximum allowable for device only rated for surge level.
But if everything is rated at surge level then the generator is slightly over built so it can handle other uses besides the above mentioned products.
(I.E)-800watt induction cookers, 20watt fans etc.

Because of the name plate surge most devices based on an hour rate actually consume on AVG 40% less than the given name plate.

Unless it's a name plate for semiconductor equipment for laptops, LCD TV's, etc where the name plate rating is within 15% of it's continuos duty.

Better to over build a generator than under build, to handle any future loads.
How long you measure the power is really up to you... If you have stable power readings (radio, lights, etc.)--Then simply Watts * Hours of use = Watt*Hours of energy used.

For things with variable usage (refrigerator, computers, laptops running from outlet and recharging, etc.)--Running for 24 hours or so can give you a better long term average.

If you have a load that varies with seasons (refrigerators, A/C, heat pumps, etc.)--Sometimes you just have to measure what you have and take a swag. Many devices (refrigerators/AC systems, well pumps) use more energy during sunny summer days--When you get lots of sun naturally.

Too small of system--It may not do what you need. Too large of system, higher initial costs and on going maintenance.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 766 ✭✭✭✭
For things that run intermittently or sporadically such as a deep freeze, fridge, sub pump leave your kill-a-watt meter plugged in for at least a few days to get a good idea of the average use.
You will find some things that stay plugged in draw the same amount of power if they are "on" or "off", such as cable or satellite receiver so getting a larger sample size of time really is not needed for those.

Solar hybrid gasoline generator, 7kw gas, 180 watts of solar, Morningstar 15 amp MPPT, group 31 AGM, 900 watt kisae inverter.

Solar roof top GMC suburban, a normal 3/4 ton suburban with 180 watts of panels on the roof and 10 amp genasun MPPT, 2000w samlex pure sine wave inverter, 12v gast and ARB air compressors.

• Solar Expert Posts: 8,606 ✭✭✭✭✭
I rigged up a system in 2000, call it the monolith, uses 2 group 27 size batteries in the base as ballast, a \$50 HD hand truck to wheel it around.
https://www.facebook.com/media/set/?...4&l=7e66e96c3c should bring up a link to the pics. I used a 60w unisolar panel, but a 100w glass panel is about the same size, Could add 2 "wings" with piano hinges and get it to 300w without too much effort.
Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister ,

• Registered Users Posts: 4
I am very impressed with the different replies and appreciate each one!

Okay, so now that I have a little extra time let me be more specific of what I am trying to accomplish. I am thinking of using a small pull behind Trailer as the "Base", steel framed road legal. I am a welder and can fabricate most of what I would need for framing, positioning, and holding needs. Of course all ideas still very welcome!

My goal is to build my first Portable Solar Station that I thought would have wings (3 panel), but not knowing until I presented my intents here. I want to build a Solar Generator vs. using my gas ones for this reason. I want to be able to go into disaster sites that have long term power outages such as what we are seeing in Texas right now as an example and set up a "call station" where people could come and sit at the table I am designing to handle no less than 12 12v plug-ins for phone charging for those with Cell Phones, Tablets, etc. so they can sit, talk, charge, etc. while making necessary calls to loved ones, insurance companies, etc. while being refreshed with coffee, safe drinking water, etc.

If my first Station goes as planned I will make more than one. I will have a Dish Network Dual Receiver and a Dish on a Tri-Pod to broadcast the Weather Channel Live for updates etc. thus the need to power at least one LED TV, I'm thinking 32" max, nothing huge but possibly two as the receiver allows two per one receiver.

The Trailer would probably start off as a 5x8 where I can have storage for items needed. I would make adjustable racks for the panels for the correct position at each location. I chose Solar for a few reasons. I am very interested in Solar power (and plan on a future home set-up), I want all emergency Stations to be quiet in the event of hearing survivors vs. the noise of my fuel Generator.

I am thinking that daylight depending on weather conditions could handle most of what I would want to accomplish with the right size Panels while also charging for lighter night use where most activity would be slower except for the TV, maybe a 12v Coffee pot. That is my basic plan.

Based on this information excluding the trailer, fabrication costs and needs, what would be the best way to accomplish this with the thought of being above the actual need so charging can still take place during use. Any cost estimates based on the above information and a break down of what I should start with? Appreciate all replies!
Lots of good ideas--But engineering is a harsh mistress...

For example, look at making coffee. The energy stored in 4 x 6 volt @ 220 AH golf cart batteries:
• 4 x 6 volts * 220 AH * 0.85 AC inverter eff * 80% of battery capacity (not a long life, but for emergency use--OK life) = 3,590 Watt*Hours of energy (~248 lbs of battery)
• 1.1 gallons of gasoline * 9 hours per gallon * 400 Watts (from Honda eu2000i @ 400 watt average output) = 3,960 WH (~56 lbs for genset + 1 gallon of fuel)
• 4.6 gallon of Propane * 27,0000 WH per gallon * 50% eff for boiling water = 142,200 Watt*Hours (40 lbs of propane+tank)
So, to make coffee/hot chocolate, you could heat ~35x as much water with a 20lb tank of propane (store in thermos to save more energy) vs using 4 golf cart batteries or a Honda eu2000i (1,600 watt) AC genset.

3,590 Watts of battery capacity * 1/0.52 off grid system efficiency * 1/4 hours of sun per day (after the storm passes) = 1,726 Watt of solar array minimum

Looking at our host's website for "cheap" / large format panels:

255
Kyocera KD255GX-LFB2
\$243.00
\$0.953 per watt

• 1,726 Watt array / 255 watts per panel = 7 panels
• 65.43" x 38.98" x 1.8" = 17.7 sq ft of panels
• 44.1 lbs. * 7 panels = 308 lbs
So, excluding trailer+structure:
• 248 lbs batt + 308 lbs of solar panels + 50 lbs of misc equipment (charge controller+inverter) = 606 lbs of solar equipment
• 50 lb genset + 30 gallons of gas * 6 lbs per gallon = 230 lbs of genset + 1 month of fuel equivalent (~9 hours per day @ 400 watt average load, or 4 hours per day ~1,600 watt load)
• 40 lb propane tank + 10 lb propane powered Mr. Coffee = 50 lbs for 1 month of coffee (Runs for 4.4 hours on one propane 1lb(?) cylinder; ten-cup total capacity)
The batteries will need monthly maintenance (even if not used), the genset fuel will need fuel stabilizer and new fuel every 6-12 months, and the propane tank will sit for a decade and not age (tank will go out of cert after ~10 years).

Not trying to rain on your parade--Just showing that short term energy production (days/weeks) is not a solar power system's strength. And for making hot water, just about anything that uses fuel (or even solar thermal water heater) would be a better choice.

There are some improvements that can be made--Use LiFePO4 batteries--Much lighter and able to sustain "surge loads" better--But probably 4x the cost of golf cart batteries. They do not require maintenance. And really do not need much charging (if at all) during long term storage (if disconnected from loads).

So--Take the same solar power system. Throw in a 20 lb propane tank + Mr. coffee for hot water. And setup for USB charging. Say it takes 6 hours @ 10 Watts to charge an Ipad:
• 6 hours * 10 watts = 60 Watt*Hours
• 3,590 WH of solar / 60 Watt*Hours per Ipad = ~60 Ipads per day (dead to full charge). Or perhaps 3x as many smart phones
Set up a bulk USB charger bank with ~30 ports, and you can charge those 60 Ipads in 2x 6 hour chunks (12 hours per day). Put in "locking charging bay(s)" and some sort of claim check system (for security). US DC to DC usb chargers, or a ~1,000 Watt (guessing) 1,000 Watt AC inverter or a pair of 300 Watt MorningStar AC inverters (not a bad idea for a spare/2nd unit for reliability) with 3-4x [URL="http://Anker® 40W 5-Port USB Desktop Charger"]Anker 5 port 120 VAC USB charger[/URL] per MorningStar.

To figure out how much power each USB device takes (and to debug bad USB cables/chargers), found that there are a whole buch of USB Volt/Current loggers.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Also, clean drinking water is probably a big need in emergency situations... 2,000 lbs of 16 oz bottled water would be ~2,000 bottles (1/2 to 1 gallon per day per person minimum?).

My prep rules (in rules of 3):
• 3 minutes without air
• 3 hours without shelter (cold rain/cold weather/no shade in hot sun)
• 3 days without water
• 3 weeks without food
Electricity is no where in there... And even if you have Ipads charged--Then need WIFI link, or Cell Towers (how many cell towers even have backup power--Not many in urban centers that I have seen).

For communications--Then look at HAM (amateur radio) and the volunteer emergency communications groups.

The days of the local phone company with 2 days of battery power and a month of diesel fuel with 2 wire copper phone lines is going away quickly. My wife wants to keep our copper phone line, and I keep a hardline phone connected (no power needed). Many people are using portable phones with no backup power--Lights go out, cordless phones go dead.

And for those using VOIP, does the cable/fiber/DSL network stay up when local utility power fails? Does it have more than a few hours of backup AC power/propane generator on poles infrastructure?

For most places, you should plan on 3 days of being on your own--And once support arrives (you with trailer, etc.), It is a whole different situation... Either the infrastructure is quickly brought back online--Or the damage is so great, the people have to evacuate. In some areas, cities have turned off fresh water--not because of water shortages, but because the sewage pumps have no power--And they cannot allow people to flush, so they turn off the water.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset