backups for power outages or going off the grid?

[tangent4ronpaul]

it's gotten better since the county trimmed tree limbs overgrowing power lines, but 6-8 times a year the power used to go out. sometimes for days. It still tends to go out 2-3 times a year. my main concern is to minimally power 2 fridges and we are looking into getting a chest freezer. That's a lot of food to possibly go bad, depending on how fast power comes back.

Anyway, I bought 6 of these in a one day flash sale from Emergency Essentials for $56 each. They are now $75 on closeout, but you might catch a better price if you get on their mailing list. With the stuff to connect them and 12V charge converter, it came to ~$400 for a 90W capability.

http://beprepared.com/goalzero-escap...lar-panel.html




Goal Zero ® Boulder 15 Solar Panel

$159.99 $74.99

Weight:
4.86 lbs. (77.7 oz.)
Dimensions:
18” high x 11.25” wide x 1” deep
Solar Panel
Rated Wattage: 15W
Cell Type: Monocrystalline
Open-circuit voltage: 18-20V
Converting Efficiency: 17-18%



These are supposed to be compatible with 12V batteries, so I was thinking about hooking them up to some deep cycle marine batteries, which seem to sell for about $100 each and attaching them to an inverter so i can run each fridge for 10 minutes or so per fridge.

Before anyone says RTFM, the company wants to sell their proprietary and expensive storage cells. I don't want to pay that much. Plug proprietary jack into our product plug here isn't useful.

So i'm looking for some tips on some things:
batteries in serial - right?
best gauge/type wire to connect the batteries.
how many batteries match/balance how many panels? There must be some formulas.
how do I figure out how long it will take to charge the batteries?
How do I figure out how long the batteries will provide power?

Two parts on that. The inverter is going to waste a lot of energy converting 12V to 120V, so how long with an inverter?

How much longer would they last with 12V appliances? you pay a premium for 12v fridges/freezers but if the difference is hours vs days, it might be worth it.

Would it be a good idea to use these routinely day to day, like hooking up one fridge or is that going to be a net loss? We pay 11.4c per KWh vs ~$100 per battery. They wear out, but how fast? how much could i save a year by removing a fridge from the power draw?
Wanted to go with deep cycle marine batteries as they should be immune from battery memory problems. correct?
Should I expect the panels to wear out?

I've also been thinking about installing a cutout switch and a generator to hook up to the furnace. Blackouts in winter SUCK!

Never tried this before, so any tips, tricks, formulas, links, etc. appreciated.

thanks,

-t

[buenijo]

Anyway, I bought 6 of these in a one day flash sale from Emergency Essentials for $56 each. They are now $75 on closeout, but you might catch a better price if you get on their mailing list. With the stuff to connect them and 12V charge converter, it came to ~$400 for a 90W capability.

This is a very high price/watt for photovoltaic panels. Please see wholesalesolar.com for better pricing. Quality panels can be had today for $1 per watt. Also, for the application you have in mind, it makes better sense to use the battery on an automobile (assuming you own one) to power an inverter. It won't be efficient to do this, but if you're talking about a few limited outages each year, then this really makes the most sense.

These are supposed to be compatible with 12V batteries, so I was thinking about hooking them up to some deep cycle marine batteries, which seem to sell for about $100 each and attaching them to an inverter so i can run each fridge for 10 minutes or so per fridge.

So i'm looking for some tips on some things:
batteries in serial - right?
best gauge/type wire to connect the batteries.
how many batteries match/balance how many panels? There must be some formulas.
how do I figure out how long it will take to charge the batteries?
How do I figure out how long the batteries will provide power?

Two parts on that. The inverter is going to waste a lot of energy converting 12V to 120V, so how long with an inverter?

How much longer would they last with 12V appliances? you pay a premium for 12v fridges/freezers but if the difference is hours vs days, it might be worth it.

Would it be a good idea to use these routinely day to day, like hooking up one fridge or is that going to be a net loss? We pay 11.4c per KWh vs ~$100 per battery. They wear out, but how fast? how much could i save a year by removing a fridge from the power draw?
Wanted to go with deep cycle marine batteries as they should be immune from battery memory problems. correct?
Should I expect the panels to wear out?

I've also been thinking about installing a cutout switch and a generator to hook up to the furnace. Blackouts in winter SUCK!

Considerations relevant to determining how long a battery will last include its capacity, the fact that capacity will fall as it ages, lower efficiency as discharge rate increases, inverter losses, energy demands, battery temperature (lower temperature lowers capacity - however, higher temperature lessens battery life). This can get you started, but you need to do research (preferably before making such purchases). I'll say that inverters are typically 80% efficient for 12v to 120v. Also, many inverters draw a certain wattage even when not delivering electricity, and this can lower the effective efficiency. You have to check this. For example, an inverter might consume 20 watts at all times. Well, if you put a 20 watt load on, then it's actually consuming 25 watts DC from the battery to provide the 20 watts AC - plus the 20 watts DC, so efficiency would be well under 50%. Research. Expect a typical deep cycle battery to last 3-5 years at best, assuming you take proper care of it. It won't pay for itself in this application.

90 watts of solar will not yield much energy. You may get 0.2-0.3 KWh per day overall average in this application. At $0.114 per KWh, that comes to about $10.40 worth of electricity per year. Off grid photovoltaic will not compete with grid electricity on a cost basis - not even close. It makes sense only when one is living in a remote region where grid electricity is not an option, or too costly to deliver.

Batteries in series? It depends on the voltage of your battery and the rating of the controller. Series adds the voltage (two 12 volt batteries in series is 24 volts). Best gage wire is the thickest you can afford, but you need to consider the amps carried to minimize losses. You need to know the wire resistance, then you can determine the losses by taking the square of the current times the resistance. This loss should be low on the order of under 5% of the highest power expected from the system. Research. Wattage of the panels should be on the order of 20% the capacity of the battery. So, if you have a battery with 1 KWh capacity, then you should have at least 200 watts of panels. Research, there are no rules etched in stone here. Time to charge battery depends on many factors - no hard and fast rule. Research. 12 volt appliances are very expensive, and don't consider them unless perhaps you are totally off grid and rely on them 24/7 - only then they might pay for themselves over their life. However, under these conditions (complete off grid solar system) the efficiency can be improved in a cost effective way to make conventional appliances powered by inverters the most cost effective option.

I think you should find a good but inexpensive MSW inverter, get some short fat cables, good extension cord, and power your fridge/freezer and other small appliances from your car battery to verify it works. You could also charge a deep cycle battery this way. It won't be efficient to do this, but it's a good option for occasional intermittent outages. Also consider the Honda EU2000i generator, or the Yamaha version. Off grid solar (i.e. with battery systems) doesn't make sense if grid power is available or for intermittent loss of power. Use a generator, or inverter on car battery for basic loads that might be lost for short periods. If you expect to lose power for a very long period, then might as well just go off grid now.

[tangent4ronpaul]

Interesting - thanks. That seemed like a really good price. Oh well.

Good leads to research.
+rep

anyone else? seems like some folks on here have done this before.

-t

[asurfaholic]

Interesting - thanks. That seemed like a really good price. Oh well.

Good leads to research.
+rep

anyone else? seems like some folks on here have done this before.

-t

I can't help much with solar questions, but a backup generator is right up my ballfield..

There are many choices and options, and based on your OP I'd recommend going a generator route as opposed to solar panels.

You can get a standby generator with a ATS (automatic transfer switch) that ties directly into your house electrical panel and automatically fires up in the event of a power loss, and shuts off after utility power returns and maintains for a certain period. This is the best option, your food is safe, even if you are not home. The generators themselves can be fueled with a variety of fuels, diesel, natural gas, propane... I know a guy who makes his own bio diesel and uses it in his car and generator.

This setup would cost you around $3500 and up. Installation is a job, but a experienced electrician can do it in a day. If you are handy i could help you over the webs.

The next best option would be to use a portable generator. You can add in a ATS, but this is not common for a portable generator due to the fact most are pull string starter by default. To use this in your home with your existing electrical system you would need to add a breaker in your panel (2 pole 30a typical) with #10 wires to a generator plug outlet in the wall near where you'd plug the gen in. These are sold at most electrical supply houses, or lowes. Your generator would plug into the outlet, which would feed through your new breaker and energize the panel. If you go this route DO NOT SKIMP, get a breaker interlock kit for your panel. This prevents your generator breaker from being on while the main breaker is on.

The pros here is the generator is less expensive, and portable too if you need to bug out, the cons being its not automatic, and you are more limited what you can run on it. You will have to only run the necessities while the generator is on.

[tangent4ronpaul]

ty! - very interesting!

what kind of a cost would you estimate for the portable generator option. Auto kickover sounds ideal, but too expensive right now.

any recommendations on specific hardware?

-t

[asurfaholic]

ty! - very interesting!

what kind of a cost would you estimate for the portable generator option. Auto kickover sounds ideal, but too expensive right now.

any recommendations on specific hardware?

-t

Just depends on how much you would want to spend on the generator, I'd get one that is at least 3500w , preferably one of the 7500w range. You can find 7500w for $750-900 and the 3500w are much less, like $350.

And everything in between.

The other parts should run less than $100.