John D's posts

I'm confused.  When I was in school I learned that capacitors (in series) do not pass DC current.  Can someone enlighten me please?

Have you tried Midstate in Bloomfield?  I would be nervous about buying used batteries.  I bought GC2's from a local (St. Louis) distributor.  Delivery was free, and they gave me credit for my dead batteries.  You can do an Internet search for battery distributors in your area, and compare prices and services.  Search for floor-scrubber or wheelchair batteries.  For me, GC2's gave me the most AH's for the money.  They were 6-volt types, so I had to create a series-parallel bank.  (Not a problem if you do the wiring right).  I haven't regretted my decision so far.

All things considered, it seems that you will be spending in excess of $500.00 for the system.  Have you considered having an electrician install an underground wire instead?  I suspect that a wire, with ground-fault protection, would be a less expensive solution.  At the same time you might consider including a lamp post as part of the project.

I don't mean to discourage you from solar, but I would respectfully ask you to consider a more practical use for it.  A small PV system with a battery would be a welcome source of electricity when the power fails. As you add to your system you'll cut your electric bill, and become increasingly self-sufficient.  When an ice storm knocked out power at my home for 7 days, my system helped to keep food from spoiling, helped to keep the house warm and well lit, provided the energy to cook food, etc.

On the other hand, what will you do with your PV system when the turtle dies?  Just a thought.

John
 

Speaking as a landlord myself, I can understand your landlord's concerns.  Removing solar panels from a roof would likely require patching of holes.  Have you considered pole-mounted solar panels?  I suspect that your landlord would not have a problem with that, as it could easily be removed without significant damage to the property when you move out.  The only thing you might leave behind is the concrete foundation.     

Additionally, your landlord has nothing to gain from your system, and I doubt that she would be willing to share any of the costs of your system. 

Are you planning grid-tied, or off-grid?  Your landlord may have issues with the electrical work that needs to be done, especially with a grid-tied system.  Mabee she would accept a deposit to cover the cost of reversing those changes, in the event that you move out.  If you're considering off-grid, you don't really need to make wiring changes.  You can simply run wiring to the areas of the home where you wish to use electricity from the system.  That would probably be acceptable to your landlord.   

Right!  Not all bulbs are of the same quality.  I have no LED bulbs, but almost everything in my home is CFL.  I've had good luck with Sylvania.  You can extend the life of CFL's by making sure that heat doesn't build up inside the light fixture.  I've actually inverted some of my light fixtures so that the base of the bulb (where the electronics are), is below the bulb itself. 

John

Beverly,

I agree with James that the best way to start is with efficient lighting and appliances, insulation, and so on.  But since your question is how to best spend your money on “solar”, I would first look into solar water heating, and then solar electricity. 

With solar electricity, you have two basic options, grid-tied or off-grid.  $1000 is not nearly enough to get a (practical) grid-tied system up and running, so I’ll limit this reply to off-grid.

If you spend your money wisely, and do the labor yourself, your $1000 off-grid system might be big enough to provide some lighting, charge a cell phone, power a radio, and not much more.  Still, it’s a good start.  You’ll really appreciate the value of your small system in the event of a grid-power failure.  As you enlarge you’ll be able to watch TV, do a little cooking, and use other household appliances.  It will take quite a bit more to provide air-conditioning and heating.  I use a bio-fueled stove and only use electricity to power the motors. 

May I suggest that before you buy anything, think about what you want to end up with in the long run.  Use on-line resources to calculate how big your system needs to be, mainly in terms of watts of PV and amp-hours of battery capacity, to meet your ultimate goals. 

There’s nothing wrong with starting small and adding to your system over time, but consider your battery strategy carefully, as it is not a good idea to add new batteries to an existing array. 

If you’ll tell me what your goals are, I’ll be happy to provide additional information. 

John

Since no one has responded so far, I'll take a stab at it.  Some inverters do accept AC input and others do not.  Some include an "Automatic Transfer Switch" which senses the presence of input AC power, and uses that power for the loads and for battery charging.  When the AC input power shuts down, the loads are switched to battery power, via the inverter.  You can also accomplish the same results with two separate devices, an inverter and an automatic transfer switch.  That's what I did.  I have my inverter set to shut down when the battery voltage drops below 12 volts.  The AC output from my inverter passes through the automatic transfer switch.  When it senses no AC from the inverter, it switches the inverter out and the grid-supplied AC in.  Works great, but there is a slight flicker (of the lights) when the transfer happens.  I'm a little worried that this glitch might damage sensitive electronic equipment, but so far I've had no problems.

I haven't had any trouble with squirrels eating my wiring (yet), but I've struggled with them in my garden for years.  I tried all sorts of things.  Finally, I bought a have-a-heart (live trap), and started relocating them to the other side of town.  It works, and it's humane.  You have to keep at it though.  Shortly after you move one out, another one moves in.  Once they find that you have something tasty, they keep coming back for more.  Not an ideal solution I know, but better than replacing expensive wiring.

And another thing...  Just be glad that you don't live where I'm living now.  We have rats the size of possums, and they eat the wiring on our cars.

John

Am I the only one who sends his wife up on the roof to brush the snow off of the panels?  Doesn’t your woman appreciate the time and money you’ve invested in a system that makes her life more comfortable?  Does she think about such things when she’s using her appliances, or putting on makeup in front of a brightly-lighted mirror?  Where does she think the power comes from to run her vacuum cleaner?  You might want to remind her that the beer she fetches for you is cold because of the system you’ve installed.  Maybe she just needs a reminder.  After that, I’m sure she’ll be happy to scurry up the ladder and brush the snow off of the panels when necessary.  I know mine is.  And by the way, happy April 1st.

I think I understand what you're saying, but you might want to consider a different approach.  Basically, you want to consume more than your system is capable of providing.  Consider an AC transfer switch (either automatic or manual).  Once you've used as much power from the batteries as you dare to use, turn off the inverter.  The transfer switch switches to grid power.  To protect your batteries, allow them to fully charge again before switching the inverter on.  The entire process can be automated, if you wish.  That is how my system is set up. 

John,

While voltage is measured “across” a device, current flows “through” a device.  If resistance is low, current flow will be heavy.  If resistance is high, current flow will be light.  Current is the same in all parts of a series circuit.  A meter is a sensitive device, only able to pass a small amount of current.  But a light bulb (a typical load), requires a relatively high current.  Putting a light bulb in series with a current meter would quickly destroy the meter.  The solution is to create a parallel circuit, diverting most of the current around the meter, and to the load.  That is what a shunt does.  A shunt is a precision resistor, of low resistance.  As a hypothetical example:  If the meter represents 999 ohms of resistance, and the shunt represents 1 ohm, and the total current flow is 1 amp, then 0.999 amps flow through the shunt, while 0.001 amp flows through the meter.  The meter is calibrated in such a way to indicate 1 amp, while the actual current flow through the meter is only 0.001 amp. 
john

Thomas;  I think there are a few issues here that come into play.  1. Due to budget considerations, not all of us have the battery capacity that we would like to have.  2.  Power consumption can be more than usual from time to time, draining the batteries faster than usual.  3.  Extended periods of bad weather limit the charging capacity significantly from time to time.  Forgetting to turn of a load can also drain the batteries faster than usual. For all of these reasons I'm glad to have added cutoff automation.  Without it, one screw-up might irrepairably damage my batteries.  I certainly don't want that to happen.  A battery monitor is a great accessory, but I'm not always home to monitor that.  Also, I hope to avoid sleep interruptions by something "beeping" on my system, requiring immediate attention.  My automation takes care of all of these issues. 
Regards, John
 

Ray,

You might want to consider a voltage-controlled-switch to sense battery voltage and turn the inverter on and off.  As you probably realize from this discussion, you need to be able to controll two set-points, one to turn the inverter off at the low point, and the other to turn the inverter on when the batteries are fully charged again.  Keep in mind that if you reconnect the batteries before they have a chance to fully charge (on a regular basis), you may damage them.  My choice for a voltage-controlled-switch was the Morningstar Relay Driver.  I love it.

John D.

As I see it, getting the most from my off-grid system while protecting and preserving my batteries is a balancing act.  I found myself either shutting down the system too soon (not getting the full benefit of the system), or waiting too long to turn it off (risking battery damage).  To help me more efficiently use my system, I've created a chart.  While this doesn't answer the questions posted here concerning controller settings, it might contribute to a better understanding of battery SOC under various conditions.  I hope you find this information helpful.

John
          http://solarjohn.blogspot.com/2007/03/measuring-battery-state-of-charge.html

Since RayLis doesn't seem to be around anymore, I'll ask the same question to everyone else: 

If you were going to invest in Renewable Energy-related stocks, which would you own, and why?

I bought some UQM recently, and it seems to be on an upward trend.  I think they're tops when it comes to efficient motors and controllers for electric vehicles.  Your thoughts?

John

Marcin, I'm a little curious.  What do you want from your system.  Or stated another way, what benefits are most important to you?  I ask because I started out with a system barely big enough to keep one CFL bulb burning for a few hours.  My goal at the time was a backup system to serve in the event of power failures.  I thought of other things of course, like cooking, heating, and refrigeration, but I didn't want my small budget to keep me from getting started.  I now have a system that will do all of those things, with limitations of course.  I've never regretted starting small.  If I had waited until I had the finances to build a system big enough to meet all my goals, I'd still be waiting.  You're right, of course, to learn as much as you can before taking the plunge, but once you get a system up and running you'll really start to learn.

John

What companies would you include in your portfolio, and why?

Thanks for the replies.  The motorized skateboard sounds too scary for me.  Jon C, your electric bike sounds fantastic!  Not only does it provide power assist, it actually puts energy back into the batteries when you're going downhill. I would be grateful if you could provide additional information, particularly regarding the parts and mechanical details.

John

Here's my situation:  I've recently started an 18 month assignment at Guantanamo Bay and I don't have a car.  I live 3 1/2 miles from work, and I've been biking to work most days.  However, the hills make the going pretty tough.  I would love to own an electric bike, but new ones are pretty costly.  I would have no problem recharging the bike at home and at work.  Whatever I buy would have to be light and compact, or the shipping costs would be high.  Also, it would have to be legal to ride here.  (Bicycle laws apply).  Any suggestions?

Ann,

You said:

I have the disconnect breaker wired...on the bottom to the positive battery bank terminal...

And:

I am taking the reading at the bottom of the disconnect breaker...and the negative post (of the battery)...

Therefore:

You have the meter connected across the battery.  In this case you would measure the full battery voltage.

John

Exeltech makes a 125-watt sine wave inverter.  I've had good luck with my 1100-watt Exeltech Inverter.  John

I was faced with a similar problem last year.  I wanted a solution that gave top priority to charging my main battery bank, and use excess energy to keep the spare bank charged.  Like you, I wanted to automate the process.  I've posted my solution here:  http://solarjohn.blogspot.com/2008/10/system-automation-for-spare-battery.html
I hope this helps. Let me know.
John

If you're reading this then you are one of the few who have an interest in alternative energy.  It's too bad that more people don't share that interest.  We had better embrace renewable energy sources before fossil fuels run out. 

At about $60.00 per solar panel this is an expensive option for a multi-panel array.  I've fabricated my own mounting hardware from aluminum and stainless steel hardware for less than $20.00 per solar panel.  These have lasted through a couple of tornado's and other nasty weather.  The details can be found here:  http://solarjohn.blogspot.com/2007/02/mounting-solar-panels-on-your-roof.html

John

Considering the abundance of problems associated with all kinds of products from China (toys, dog food, human food, etc.), I'd be reluctant to buy Chinese-made solar panels.  Even if they do perform as advertised, I wonder if they will continue to perform well in say 10 years...  Chinese manufacturers may someday turn their image around, just as Japan did with electronics products many years ago, but I just don't see it happening in the near future.  But hey, that's just my opinion.

I'm no expert, but wind turbines need to be quite a bit higher than the nearby trees in order to operate efficiently.  What is your budget? 

There are so many things that can be done that I hardly know where to start.  Perhaps the best approach is to make conservation a way of life.  Here are a few thoughts concerning groceries and shopping:  When it's time to replace an appliance, get the most energy-efficient model available.  However, don't get a refrigerator so small that it necessitates extra trips to the grocery store.  Buy locally-grown food as much as possible.  Grow your own food, indoors and outside.  Learn to preserve food for consumption off-season.  Use greywater for lawns and gardens whenever possible. 

Tech Guy:  I suspect that being grid-tied is not the solution you're looking for, right?  If that's the case, you might consider an automatic transfer switch like this one:

http://store.altestore.com/Enclosures-Electrical-and-Safety/Miscellaneous-Electrical-Parts/Switches/Transfer-Switches/Iota-Relay-Based-Transfer-Switch-30A/p694/

Without more details from you, I can't suggest how you might implement it. 

I'm not sure how to respond to others who've posted here recently.  I'll just say that I don't want to walk around in the dark, bumping into things.  God certainly didn't bless us with all of these natural resources, and expect us not to use them.  Perhaps the moral in Thomas's story is to use resources responsibly, avoiding problems in the future.  And finally, going back to a simpler time would just empower those who take advantage of the weak.  No thanks MB.  Not all of us have become fat, spoiled children.
   

You can measure the angle with this tool, and then use that measurement for your calculations. 

http://www.claimsadjusters411store.com/jopisllo.html

John

My dedicated loads are my refrigerator and a chest freezer.  I've been adding solar panels, and I've upgraded my battery bank a couple of times, as my budget permits.  I look forward to the day when I'll have enough capacity to run these loads entirely off of solar power. 

When I need to conserve, as in the case of a grid power failure, I don't run the refrigerator.  I keep the freezer going in order to protect frozen food, and I use an ice-chest for items needing refrigeration.  By doing this, I have enough capacity to run a few lights, and other household items.

I like PV because it's reliable, and requires little maintenance.  I would like to eventually eliminate my use of all fossil-fuels, but that is a long-range goal.  I've already installed a bio-fueled stove and made many energy-efficiency improvements.  Check my Gallery on this website, and my Blog for more info.  http://solarjohn.blogspot.com

John