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Old 07-10-2012, 09:54 PM
 
Location: SC
8,560 posts, read 8,361,009 times
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Default Decent Portable Solar Generators that....

don't cost an arm and a leg.

I've seen info-mercials demonstrating solar generators that you can take around your house and plug in 2-3 appliances at a time and run them. Are they any good?
What is a fair price to pay for something like that? Does anyone have one?

My father rigged up a little 6 inch by 8 inch solar panel that kept a battery juiced up that ran a bildge pump in a sailboat we had and it was very reliable and I don't think cost a lot of money at all. All we had to do is make sure to remember to leave the solar panel out in the cockpit after going sailing) so it could soak up the sun rays.

It would be great to have a quiet source of power (not one of the noisy gas powered generators) to be able to plug a freezer into for a few hours (and I can think of lots of other examples of uses of appliances I'd like to be able to use -- at least sparingly).
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Old 07-11-2012, 12:30 PM
 
Location: Backwoods of Maine
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Not sure what you mean by a "portable solar generator". What you have described is a "portable solar collector" (solar panel) with a battery that it keeps charged, and the bilge pump runs off the battery, not the solar panel. In other words, a 12V DC system that many boats and RV campers use.

Yes. solar is quiet (silent, actually), but unless you get into a very big (and expensive) solar array (group of panels), they will not power a freezer alone, unless you have a battery bank. A bilge pump draws substantially less power (amps) than a freezer would. So you aren't going to run a freezer (even a 12V one) off a "little 6 inch by 8 inch solar panel". All that will run is a modest outdoor light, or...a little bilge pump. And why would you want to run a freezer "for a few hours"? It will take longer than that just to freeze the food.

You should start at the power consumption end (the appliances you wish to run off "solar power") and calculate the amp-hours you will require. Then you size the battery bank to provide that. Then, you size the solar panel to keep the bank charged. That's the order you need to do things in. And if these appliances run on AC, you'll need an inverter to convert the DC power to AC power, which has inefficiencies that you'll need more power to overcome.

My answer to your other question is, no -- nothing sold in info-mercials ever runs as well as they say. They just don't!
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Old 07-11-2012, 10:37 PM
 
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propane freezers and fridges work very well and are very quiet.
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Old 07-12-2012, 01:16 AM
 
29,990 posts, read 19,374,065 times
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Quote:
Originally Posted by Nor'Eastah View Post
....................My answer to your other question is, no -- nothing sold in info-mercials ever runs as well as they say. They just don't!

If it is the infomercial I'm thinking of (Solutions from Science) please be very wary. Look carefully at what they offer and then look at what you may purchase the relatively few components for seperately from a place like Northern Tool or even Amazon for less money. The shipping alone that you would save might be as much as 1/3rd of the price of the advertised product in addition to purchasing the compenents in a less convenient, some assembly required package.

For instance, an 800 watt inverter like this, hooked up to your vehicle battery with your vehicle idling for a couple of hours would do the same job, though granted, not as quietly. Amazon.com: Duracell 813-0807 800 Watt DC to AC Digital Power Inverter: Patio, Lawn & Garden

In the case of the recent storm related power outages in the East, many people lost food from the refrigerator/freezer simply because it didn't occur to them, or they had no means, to cook and/or can the food, without electricity. Using up what is most perishable first is key. A second lesson is that one should keep some fuel stored if possible, even 10 gallons and an extra propane tank or two for cooking on a camp stove/grill would go a long way and be much less expensive than a $2,700.00 "portable" solar generator.

Link to timely podcast: Steven Harris on Dealing with a Large Scale Blackout Part 1 | The Survival Podcast
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Old 07-12-2012, 07:59 AM
 
Location: SC
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Yes LifeLongMOGal, the ones I was thinking of are from Solutions from Science. Here's a pic and a price
PowerSource 1800 | Solutions From Science

I'm thinking about solar vs. propane because I don't want to be dependent on vendors. I was hoping for an unlimited stream of energy even if it only powered a battery that could supply power to a few appliances at a time.

Besides, I doubt a Propane company would be willing to come in; set up a tank or two filled with propane that would be used just for emergencies. Even if they would be willing to set it up; if there was a long term power outage, I'd probably use up the propane and if I wasn't able to get it refilled, then what?
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Old 07-12-2012, 10:00 AM
 
Location: SC
8,560 posts, read 8,361,009 times
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Come to think of it, if you are talking about the small propane tanks people use for a gas grill. I guess that is doable. Then I'd have to go buy a Coleman stove to use with it. I already have a handy dandy single burner that uses aerosol can cartridges (kind of) that must be propane filled. I should just look into getting a bunch more of those.

I'd still like to hear from someone that has figured out how to charge batteries with a solar panel. I think a big battery; a solar panel and one of those inverters that you hook to your car battery might do the trick. I'd rather hook the inverter to a solar panel than to my car battery and have to keep running my car and asphyxiating myself and the neighbors while doing it (not to mention wasting gas).
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Old 07-12-2012, 10:09 AM
 
Location: Backwoods of Maine
2,114 posts, read 2,565,075 times
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Quote:
Originally Posted by emilybh View Post
Besides, I doubt a Propane company would be willing to come in; set up a tank or two filled with propane that would be used just for emergencies. Even if they would be willing to set it up; if there was a long term power outage, I'd probably use up the propane and if I wasn't able to get it refilled, then what?
You can purchse your own 20 lb (grill size), 30 lb, and 40 lb propane bottles and bring them in for filling. I stopped at 40 lb because I know my wife can handle the 40 lb bottle. We have many, many of these filled and ready to go (we cook with propane, and have a propane heater as well). They can be safely stored outdoors year-round. If you don't wish to buy the bottles and have them filled yourself, any propane company will be happy to deliver a bottle from a simple 100-lb to a long 1,000 lb submarine. If it doesn't need a refill, you just pay a small annual rent for the bottle. Not a big deal at all.
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Old 07-12-2012, 10:30 AM
 
Location: Somewhere in northern Alabama
11,335 posts, read 25,061,985 times
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The "Solar Generators" are a scam, pure and simple. I recently advised a distributor who wanted to make a similar but less expensive combination of solar panel/battery/inverter. There are variations on the theme, we recently got an invitation to homeowners in our area for a free meal and presentation on a "new" energy idea for homes.

The core or the problem is that the gel-cell batteries in the devices are grossly undersized for any serious use, and the panel isn't enough to keep it supplied with "fuel."

If you want to spend that type of money and want something quiet, Honda makes a line of very quiet generators that can be ganged together. RVs also often have very quiet generators. Remember that there is no way you can make power at less cost than an electric company can deliver it to your power pole. (The cost of setting that pole can be huge in a rural situation, though.)

My current compromise is a disposable 1200 watt generator that I purchased from Aldis for $100. It is reasonably quiet, and I don't have to worry about disturbing neighbors anyway. Five gallons of gas means that for $120, I have insurance that I can keep our freezer and refrigerator cold for at least a week with proper fuel and use management.

Stay far far away from those packaged "solar generators."
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Old 07-12-2012, 10:54 AM
 
Location: Backwoods of Maine
2,114 posts, read 2,565,075 times
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Quote:
Originally Posted by emilybh View Post
I'd still like to hear from someone that has figured out how to charge batteries with a solar panel. I think a big battery; a solar panel and one of those inverters that you hook to your car battery might do the trick. I'd rather hook the inverter to a solar panel than to my car battery and have to keep running my car and asphyxiating myself and the neighbors while doing it (not to mention wasting gas).
You already have heard from someone who has it figured out - me. Charging batteries with solar panels is easy - just hook 'em up. You still have not mentioned whether you wish to run 12V DC or 120V AC appliances, and how many at once. This has everything to do with what you'll need in terms of battery capacity, solar panel wattage, and inverter size!

Let's assume you wish to run your refrigerator and freezer during an outage. You need to know the amp-hours that each of these appliances uses, and add them together. When you buy your battery bank (just one "car" battery won't do the trick), you choose the total capacity of the bank based on these 2 appliances you wish to run off it. They can help you size the bank at the store where you buy the batteries, which are called "deep cycle". They will be quite heavy.

Once you have your batteries, you need to keep them charged. This is where the solar panels come in. But you need enough wattage in the panels to keep the battery bank charged with a typical day's worth of sunlight where you live. You'll also need a charge-controller so that you don't over-charge the batteries and fry them. The inverter also has to be sized correctly. If it's too small (say, 400 watts), you won't get the AC power you need. And the inverter is always connected to the batteries, not to the solar panel.

My best advice is for you to get professional advice on the sizing of these components. If even one component is sized wrongly, it can upset your whole day. Oh - and one other thing: such a system needs to be used, preferably on a daily basis, not just during an emergency outage. If you just let the batteries sit and do nothing for months on end, they will let you down. These systems can be a bit complicated, as you can see, and that is likely the source of your frustration. There is no one correct set-up for all people. That's why the info-mercial idea won't work for most people.
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Old 07-12-2012, 05:51 PM
 
Location: Interior AK
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If you want to run a freezer or refrigerator via Solar PV, either direct or via battery, you'll have much more success getting a highly efficient unit that is designed to operate with this power limitation. There are a few DC fridge/freezers that are designed to run DC-Direct from one or two mid-large PV panels, not a huge array - but not a dinky portable panel either, but it's still advisable to have a battery or two with charger in that system for night-time and back up.

For any large, power-heavy appliance that itself isn't portable, you are MUCH better off getting a higher watt panel (or array) permanently mounted with a charger and at least one good deep-cycle battery (and inverter if the appliance is 120v AC). The low-watt portable panels are really only good for trickle charging batteries or powering small devices. You can't power something that requires 500w with a 60w panel alone, basic laws of physics. So you can either buy two 300w mounted panels or ten 60w portable panels to power that device... and the two 300's cost less, especially when you factor in all the other cabling and system components.

Solar PV isn't rocket science, no matter what the experts and charlatans try to tell you. If you can do basic math, wiring, and welding/carpentry you can design and install your own system following a few simple rules and instructions. Yes, you may need more in-depth knowledge of electrical engineering to perfectly optimize a system, but you can put together an adequately functional system "eyeballing" it with your layman's calculations if you aren't star-struck with all the fancy stuff.

PV collector > cabling > charge controller/switch > cabling > battery storage > cabling > DC appliance and/or AC inverter > AC Service Panel and/or AC Appliance. That's it... if you can hook up your cable box, antenna, vcr/dvd, and TV then you can install Solar PV. It's not like you have to build the individual components... just put them together.

As long as you keep the voltage consistent and the produced wattage is close to the required wattage, the only even vaguely difficult math and decision is getting the number of batteries right (amp-hours of storage) and the right breakers/fuses in the right places. Once you have a good understanding of how parallel and series wiring configurations work and how that affects voltage and amperage, you're pretty much good to go. It really doesn't have to be that complicated.

In layman's terms: watts is the quantity produced or used, amps is the flow rate, and voltage is the pressure. The cable gauge you use is dependent on and impacts the amps and voltage.

Using water as an analogy: You have a tank that holds 5 gallons, you can only have a maximum of 5 gallons for use unless you ADD another tank or a bigger tank (wattage). How fast your tank empties or fills (amps) depends on how big a pipe (cable size) you're using and the pressure (voltage) pushing the water through the pipe and out the other end. Making the pipe smaller decreases the flow rate, increases the pressure within the pipe, and requires more pressure if you want to maintain the same flow rate. Making the pipe larger increases the flow rate, reduces the pressure within the pipe, and requires less pressure to maintain the same flow rate. If your pipe is too small or has a lot of bends/blockages (resistance) and you force a high flow rate, it will burst (melt your wiring). If your pipe is too big, you'll only have a weak trickle at the other end and you've wasted a lot of money on pipe.

The basic rules:
  1. 12v+12v in parallel=12v for twice as long (increased amp-hours storage in battery)
  2. 12v+12v in series= 24v for the same amount of time (increased voltage produced from panel or battery)
  3. 100w+100w in series OR parallel = 200w (increased wattage from panel)
  4. In parallel systems, you can add any number of units to the system at any time as long as they are the same voltage. (you can add 1 or 100 12v batteries to a 12v system it doesn't matter)
  5. In series systems, you have to add the correct number of units to the system to maintain the correct voltage. (you MUST add PAIRS of 12v batteries to a 24v system OR rewire and step down to a 12v system and upgrade your cabling if necessary)
Battery overcharge is dangerous and expensive, but can be mitigated by having a charge controller and switch that shunts surplus power to a power sink appliance when the batteries are full. Electric water heaters are EXCELLENT for this purpose, since they are super-INefficient appliances. Other solutions are 1) don't oversize your system in the first place, size it for the average (or minimum) usage NOT peak usage; and 2) get a charge controller with an alarm and then run heavy-power appliances like washing machines, vacuum cleaners and power tools when you're producing surplus power. Note that I don't mention grid-tie with no batteries... it's an option, but if the grid goes down, you just lost your storage and can only rely on production (which is better than nothing, but suboptimal).


Why not stay at 12v?
As voltage goes up, amperage goes down. The lower the amperage the less power is lost in the cable due to resistance... which means less expensive cabling because you can either use thinner cable for the same span, or run longer spans for the same gauge cable. If your appliance is at or near the source, then 12v DC is fine; but trust me, unless you get an awesome deal at Craigslist or Freecycle, long runs of 2/0 awg or 4/0 awg cable at $5-10 a foot gets expensive (and heavy!) quick ... that $$$$ would be much better spent on production or storage rather than transmission.
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