Solar Panels and Back Up Batteries

[Orange Guzzi]

I would like to purchase some solar panels for temporary backup power with back up storage.  A wind turbine would also work well at my home due to my physical location on top of a hill.    Battery charging, radio, computer, wi-fi, some light, small chemical/water pump and maybe refrigeration.  What say you all that have temporary power supply?

Best type of battery for storage and charge, discharge cycles, output voltage, amp hours

[Triple Jim]

You need to start with the watt-hours you need to run your loads.  Make a list of each load's watt requirement and how long you need to run it, in hours.  Then add all the loads up and you'll have the total watt-hours.  Then decide what battery voltage you're going to use.  Assuming 12v, divide your total watt hours by 12 to get amp-hours.  Choose an array of batteries rated for about double that, since you don't want to discharge a lead-acid battery more than about 1/2 way very often.  Conventional lead-acid batteries, and AGM batteries are probably the only reasonable choices.

Choose an inverter rated for a continuous load of something well over your expected peak load in watts.  Motors need about 5 times their rated running current for starting.  You may be better off with more than one inverter.  A good one like an Exeltech that put out clean sine wave AC and has plenty of overload capacity and circuit protection is needed for a reliable system.

Your solar array's size depends on  how quickly you want to be able to recharge your battery after it's discharged.  Figure about six hours of sun per day, and count on about 75% of the output current that the manufacturer specifies.  If you have 100 amp-hours of 12v battery, and a solar array that's rated at 4 amps, you'll need about 5-1/2 days to recharge the battery if the weather is clear.

A 24v system may help if the battery current requirements start needing huge copper wiring.  I built a sort of pontoon boat that's battery powered and recharged with solar panels on the canopy.  It has four 115 amp-hour AGM batteries in series, making a 48v system.  Even so, the battery wiring is pretty hefty, and fuse protection at the battery terminals is mandatory.

[zedXmick]

Here is some info about wind,when i was researching wind power,this product just stands out. UGE is the name of the company.  They do solar and wind.

http://www.urbangreenenergy.com/products

[Perazzimx14]

What's your budget? You can easily get $1000's of dollars wrapped up. You can buy a small generator and lots of fuel for less. Having put in one of the biggest (at the time) evacuated tube hot water collection systems solar energy is still a feel good thing.

[Triple Jim]

What's your budget? You can easily get $1000's of dollars wrapped up.

That's for sure, you'll definitely be well into the thousands for a usable and reliable system, between the solar panels, inverter(s), batteries, charge controller, hardware, and electrical controls.

[pressureangle]

Here's mine;

Batteries, ~$700
Charge controller, $450
Panels (3x125w) ? came with old boat
1800w inverter, $100 @ pawn shop.

Obviously still in progress, just got the panels on the roof a week or so ago. I had the panels, batteries and controller for a sailboat I had, so kept them so we'd be able to charge phones, computers, whatever if we have a hurricane and lose power. I also use the set to run a roof vent fan in the garage. Being in S. Florida I have plenty of sun all the time.

[Lannis]

I would like to purchase some solar panels for temporary backup power with back up storage.  A wind turbine would also work well at my home due to my physical location on top of a hill.    Battery charging, radio, computer, wi-fi, some light, small chemical/water pump and maybe refrigeration.  What say you all that have temporary power supply?

Best type of battery for storage and charge, discharge cycles, output voltage, amp hours

With utility energy available at $.10/Kw-hr, individual wind and solar is going to be some of the most expensive electricity that you'll ever use, amortized over the equipment acquisition, maintenance, and battery life costs.

If it's REALLY important that it work when the grid quits and you don't expect it to come back up soon, and you don't expect to be able to get diesel for a generator, then it would make sense. 

Dollar per watt-hour, though, you'd be better off buying a proper sized generator and starting a fuel fund.

Unless it's just a hobby and something you want to do, nothing wrong with that.  Then the cost doesn't matter much.

Lannis

[RinkRat II]

 Hey There O G, my  $.02 on this , if you can get your mitts on some forklift batteries they'll just about last a lifetime. Material handling outlets change them out on big customers lease foklifts and some will sell them off at a pretty good discount. Second is the wind turbine,if you've never been around one running full out, they can be noisy. If far enough away from the house no problem. All the other advice so far ...spot on!  Good Luck!

    Paul B :BEER:

[rodekyll]

Another good place to look for batteries is out behind the parts house.  They take in cores and set them on a pallet outside.  I've found as many as 35% of the batteries in those piles are good, and by bridging cells to bypass sulfated ones, I can coax a few amp-hours out of almost anything.  The housescow owners in my town raid the stashes regularly.  They have many rows of them below decks.  Some recharge with arrays of car alternators.  Some use both wind and water.  Nobody up here uses the sun.  Why would we?

[redrider]

Interesting thread. Solar vs. generator. Fuel supply seems to be the point. Solar is expensive to install and maintenance on the batteries is a chore. At least the fuel is free. Generators need fuel but are easier to maintain. A steam powered system could be an alternative to both.

[Lannis]

Interesting thread. Solar vs. generator. Fuel supply seems to be the point. Solar is expensive to install and maintenance on the batteries is a chore. At least the fuel is free. Generators need fuel but are easier to maintain. A steam powered system could be an alternative to both.

That's what you generally use when you plug into the wall (except for the hydro component).

How you going to make the steam without concentrated sunlight and without fuel?

Lannis

[Testarossa]

All of the above is good advice.  What you really need to do is focus on your real needs. What kind of emergencies are you preparing for? You're in Indiana, so it's not hurricane, but it might be winter storm, river flooding, tornado?

In any case, make a list of the stuff you can turn off and the stuff you absolutely have to run.

If winter storm, first priority is heat. Wood stove or if you run a furnace you'll need backup electricity to run the the blower. Winter storm and flooding are the situations where you're most likely to run out of diesel fuel and not be able to get a delivery. So if you do put in a generator, consider what kind of tank you'll need. Lesson of Fukushima (and Katrina) is that in any flooded area the generator and fuel supply need to be elevated above flood level. Duh.

Wind is not a practical solution if you're preparing for tornado or hurricane. High likelihood of losing the equipment.

Solar doesn't have to be as expensive as people make out. Nowadays panels wholesale at 80 cents a watt -- and you can buy old panels for a lot less. Panels carry a 20-year warranty that says they'll produce 90% of rated power for 20 years; a business upgrading to more efficient panels may sell off the old stuff  still producing 95% of original wattage for 20 cents a watt. They're not as efficient as the new stuff but you don't need "bankable" power. Used forklift batteries are in fact a great idea. That leaves the inverter. You can get something like an SMA Sunny Island to create a microgrid (it turns itself into a power island automatically when the grid goes down), or just rig a cheap square-wave inverter to run lights and motors on a separate circuit. You only need sine-wave power to run electronics.

Finally consider leasing a solar system. No upfront cost. Tesla will introduce its home-and-farm battery backup system late next summer and SolarCity will lease the stuff on a 20-year contract. If you have the cash (or access to low-cost credit) it's a better financial deal long term to own the system outright, but leasing is a pretty painless way to get a system if you don't have cash. And someone else does the engineering, installation and maintenance. On the other hand, solar leasing companies may not do business in your area.

[Doppelgaenger]

I ran a farm that was off-grid for about 5 years, all our power was from solar and it ran the drip irrigation systems as well as everything else. Eventually we went to grid-tie and ran the meter backwards. From that experience I can tell you that having solar is by no means cheap or low-maintenance. I can also tell you that you need to drop some serious cash on a generator if you want something that is even remotely worth a damn.

From either solar or wind, you most def need deep discharge batteries or you will ruin them in no time flat. The suggestion of forklift batteries is an excellent one, although they are extremely heavy.

while I love wind power, turbines are noisy and they don't last too long. however if you get consistent wind it would be wise to tap that power since that way you might get the ability to charge at night. There are very well established rules regarding how much wind you need to make investing in a wind turbine worthwhile, and that threshold is higher than you might imagine. I suggest you read up on that before going down the wind road.

Finally, I would spend the extra money and set up the system so that you can run at least part of your house load off the solar/wind system at all times. There is no sense in buying something for backup power that you never use when the fuel is delivered free every day. It's like buying a jeep and then never driving it except for the one day you get snowed in. You want to use it to offset your energy costs, and turbines, panels and batteries will degrade no matter if you use them or not. Might as well make the depreciation work for you.

If you're looking for a tiny amount of backup power then you should cobble parts together. If you're looking for more substantial power then you should go with a well known name. Sunpower is a good one and they are actually made in the US and offer integral solutions. Their panels are more expensive but they're more efficient and end up costing the same per watt. Chinese panels aren't bad, but their business tactics regarding the industry are deplorable.

[redrider]

I suppose a Fresnell Lens wound be good for heating the water but you need a storage system. My experience with material handling/forklift batteries is the operators do not give a damn about using the proper method to recharge and end up severely shortening the useful life of the battery. Not to mention the case corrosion from improper filling. The largest I've worked with was a 72 volt baggage handler at the airport.

[Arizona Wayne]

We have a 24' toyhauler self-contained trailer that already has a converter in it for both AC/DC operation.  I've added an inverter for running the microwave if we lose AC access.  Propane for heat/stove/fridge and the rest is 12V run.  I just got  100W Renogy solar cells/controller/cables and am adding another marine battery for charging the batteries.  Also have a 1500W portable gas generator.


Solar cells come in different kinds of construction and some last a long time, some don't.  ;)

[Silver Goose]

Well Orange, I applaud the fact you are looking into Solar/Wind power. I have been off grid in my shop for almost seven years. I run solar and wind. I have built a sun tracking system which adds several usable hours to help gather the sun's power.

My advise is to first check with the USGS site for wind conditions/speed, you can find out on average the number of sunny days in your area. Where I live the average is 277days of sunlight, yes I know some will say 365 days, but not every day's sun light  will be bright enough to produce some power. I have sold solar hot water systems to motels in the area. The first system installed had a projected return on investment of seven years. Actual payback was 6 years.

In order to reduce the costs and increase your return you must do more than add panels. Change lighting systems, high efficiency light bulbs. Turn off any standby power users, except medical devices. Invest in the most efficent panels possible,18 to 21% seems to be the high end at this time as opposed to Harbor Freight at near 6% efficency. Next get the best inverter, if you plan to run a TV or a computer on the system use a full sine wave inverter. Full sine will mimic the power you are getting from the grid. If you are just running lights and charging batteries modified sine will work, again look at the efficentcy rating. Many low end inverter can consume 18% of the input power.

Check with your state many will offer tax reductions for alternate power users. A federal tax reduction of up to 30% is still in effect until 2016.

Remember, start slow and build the system yoou want.

Good Luck

[Jimbolong]

I have a computer in my basement that I use as a file server (running the Unraid OS).  I want to keep it on at all times, so I decided to try solar.  My primary motivation was really just to learn something about solar, the computer was just an excuse, I will never recoup my investment from the offset of my electric bill.  I bought a system consisting of the solar panel kit, inverter, and battery as shown in the "frequently bought together" section on this Amazon page.

http://www.amazon.com/Renogy-100W-Mono-Starter-Kit/dp/B00BFCNFRM/ref=sr_1_1?ie=UTF8&qid=1424049916&sr=8-1&keywords=solar+panel

I learned that I didn't have enough stored energy to keep my machine running continuously.  Sometimes it would make it through a compete 24 hour cycle and sometimes it wouldn't.  The first thing I did was to buy a second battery, thinking that the 35 amp-hour capacity was not enough.  This helped, but still didn't do it.  I made some power measurements and learned that my oversized inverter (1000w inverter powering a computer that drew less than 100 watts) was not very efficient at (relatively) low power, so I bought an inverter that was much closer to the power I was using.  This helped, but still, if I had an overcast day and didn't collect much solar energy, I would drain my batteries before the sun came back.  I finally gave in and built a switch that switches over to line power when the battery voltage falls so low that the inverter shuts off.  The system has been totally stable since.  I think the lesson is that you follow the advice of my old scout master.  "When putting leaves in your tent to make a comfortable bed to sleep on, you put in as many as you think will do the job and then you go get that many more."

I would echo the advice of an earlier poster and say that if you are just looking for power for an emergency, by a generator.  I have had one for several years (only about 1800 watt capacity) and it keeps my essentials going when the power fails.

One final thing, after all of this, I have decided to have solar panels installed (professionally) on my roof.  I have opted for the highest kwh system that was recommended.  I might not have gone this high if I hadn't gone through my little exercise.

[Arizona Wayne]

I know a guy down in the Delta with a rice farm. He had those solar panels and then he add a wind turbine. It's flat and windy in that delta. He said that wind turbine is the ticket. It supplies all of his power and then he is selling power back to PG&E. Only issue is PG&E sets the buy back rates. I understand they are passing a law so that private guys like him can barter that rate up with the power companies or choose to sell that power to other sources who would bid on that excess power. Right now the way it's set up the power company you fall under can set the rate as low as they want and they have a captive audience. Monopoly if you will. All about to change with new laws. In the future we will end up with private own wind farms because it will become profitable for private venture. Right now the big power companies have a monopoly. That is preventing private investment with wind farms.

I've read the commercial wind 'turbines'? are high maintenance are aren't really as economical for producing electricity as believed.

Here in Kingman we have some constant wind in places and have some small private wind turbines around + some solar systems for businesses.  We get sunshine 365 days a year here. But we also have a co-op electricity Co. so our cost for that isn't too high either.  ;D

I have a small $19 solar panel for charging a battery that produces 19V in direct sunlight.