I'll bet I'm not the only forum participant concerned about global warming and/or our dependence on foreign oil. As much as I'd like to convert my whole home to solar Photovolactic power, without more incentives than those available in Wisconsin, it currently doesn't work economically. Not on a system that would cost me at least $75,000. Besides, my major chunks of spare cash are putting two kids through college.

But I'd like to experiment a bit, preparing for the day when solar PV is a bit more cost effective. I ran across this article on getting your toe wet and gaining experience by taking a bedroom off grid.

www.off-grid.net/2008/03/27/take-one-room-off-grid/

I thought, "If you can do that with a bedroom, why not a garden railroad?" By the way, this approach could work for any of you that would like to run a GR in a location not close to grid power.

Why did I post this here? It's the battery power forum isn't it? Solar panels are being used to generate power which is stored in batteries. Power is being drawn from the batteries to power stuff. Sound at least a little similar to some of the other posts in this forum? Now if I could get Tony Walsham enthused about developing a radio control system to manage an entire solar powered railroad ...  
 
(Note: This was orginally posted to the R/C Battery forum)

Yes, the scale of the battery power in this project is somewhat greater than the scale of most battery power posts to this forum. But I consider this to right on topic for this forum. And you are the august group of participants in MLS most likely to be able to help me out.

My North Pacific Coast garden railroad almost came alive at the end of last summer. The track was laid. The golden spike ceremony was set. I just ran into a few last minute problems getting power to the layout. So a bunch of friends attended and complimented me on the static trains I had on display. I won't get into the power snafu here as it might subject me to ridicule from this group. But I've been obsessing about power all winter. Now that the 100" of snow we received in Madison, WI this winter has mostly melted, I'm about ready to get going.

The NPC was built to be a radio controlled, battery powered layout - the old fashioned way - packing rechargable batteries in tenders and battery cars. I also planned to light my structures with solar power outdoor light components. That won't change. You might say, "Farin, you're already off the grid with battery power and solar." That is an incorrect statement for a number of reasons.
(1) The batteries need to be charged. I'll bet most of you do it with grid power.
(2) I have a very nice string of old fashioned metal low voltage lanterns that will be used to illuminate the walkway running through the middle of the layout. Input to the transformer powering these lights is 120V AC.
(3) There will be a water feature requiring a lift pump to bring water from the catch pond at the bottom of a stream back to the top.
(4) I ran 20A 120V lines and placed outlets all around the layout for occasional and possibly unplanned continuous use.
So what I'm talking about is taking all of the above off the Alliant Energy power grid and substituting a small off-grid setup conceptually along the lines of that pointed to by the bedroom link earlier in this post.

I've researched the components and have refreshed my mind on electrical math. Five books on solar PV power are on their way from Amazon. So I think I can deal with the general issues - what components to use and how much capacity I will need. I plan significant overcapacity in all but the solar panels and battery banks so I can upgrade later.

Here's where I can use some help.
(1) Have any of you ever tried this stunt? If so, I'd appreciate learning from your successes. And from your failures.
(2) It seems ludicrous to generate 12V DC with PV panels, charge a 12V battery, invert the battery output power to 120V AC, then plug in transformers to convert back to DC to charge the batteries my engines will pack. Any thoughts on a shortcut?
(3) The same could be said for the pump that will move the water except the AC back to DC step would be skipped.
(4) The same could be said for the low voltage lanterns. DC to AC to DC.
(5) What are the gotchas I'm missing?

I'd also welcome comments from anyone intrigued by the idea that would like to network on implementation.

By the way, I realize this is not the most cost effective way to power a garden railroad. But then, is there anything about a garden railroad that is cost effective?

It's a hobby, and an opportunity to learn something new while making a very token contribution to solving some of the problems we all face.

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Response by Cale Nelson

I have seen Solar lift pumps for garden ponds-google should help there! you could always replcae the bulbs in your old lights to LED's and power from solar (or even retrofit some solar bulbs into them)
Interesting stuff for sure! Good Luck
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Response by Del Tapparo

It's actually difficult to find an AC input battery charger. Look at the R/C car and Airplane hobby shops. Most of their chargers take a 12 volt input, usually their car battery when out in the field.
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Response by Dale Ottney

The RC flying club I belong to has a solar panel charging a deep cycle battery at each field. The battery is connected to panel that allows us to connect chargers for flight packs. This works very well and gives us the ability to recharge packs without using our vehicle batteries. I can't see why this type of setup couldn't be used for model RR'ing.
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Response by Jimtyp

For a charging batteries for a loco could you use one of those solar garden lighting systems? 
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Response by tom Lapointe

Most inexpensive solar panels provide only a few milliamps (1 milliamp - 1/1000 amp) of output, vs. the AMPS most LS locos require.
In short, to run a loco maybe an hour or so a week, you MIGHT have to have it on your "solar charger" ALL WEEK.
This is also assuming LOTS of sunshine (no rainy or cloudy days ). I also would try it ONLY with either Nicad or NiMH batteries, NOT LiPo batteries because of their intolerance for improper charging.
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My Response to the above responses

Cale,
Thanks for the tip on solar lift pumps. After spending some time with Google last night, I found many are too small for the lift I need. On the other end of the spectrum are solar well pumps for watering livestock and the like - $1,000 on up. But there is a much wider range of DC pumps than solar DC pumps. I need to spend more time figuring exactly how much GPH I'm going to need. I should be able to find a solar pump or a DC pump powered by my solar setup that meets my needs.

Also, I calculated the power needs of my string of low voltage lights. Let's see, 18 Watts times 13 lights is 234 Watts. Assuming 4 1/2 hours of lighting per evening and 4 1/2 hours of sun per day (wisconsin average) it would require 250 watts of PV panel at about $5 per watt - Yikes - $1,250 worth of PV panels just to run the lights (not counting batteries and other stuff). As you point out, I could replace the 18 watt bulbs with parts from solar lights for about $7 a light --- $91 plus some labor - not a difficult decision to make. In addition I pick up a photo sensor at each light that knows when to turn it on and off.

Del & Dave,

Never even thought about the radio control battery operated car market. I know a whole lot more now than I did 24 hours ago. You are right. Take two 7.2 volt packs, wire them in series and you have 14.4 volts of battery power. 7.2 volts is a real common RC battery pack voltage available in a variety of NiMh battery form factors for different engine sizes and power needs. And you are right, there are plenty of DC chargers that take 12 volts as an input voltage and charge 7.2 volt packs. In addition if more voltage is needed, there are 8.4 volt and 9.6 volt packs.

Jim,

The reason why you want to go with a purpose built charger is to stop charging when the batteries are fully charged, trickle charge to maintain, and cycle batteries that are performing in a less than optimal way. I had been thinking about one of the Maha chargers and discovered last night that the MH-C204F can accept both 120V AC and 12 V DC. But the problem that creates is charging individual 1.2 volt AAA or AA batteries which once charged are pressed in place in a holder rather than soldered together in a 7.2 volt pack. I like the RC approach better as it offers a much wider range of battery form factors, voltages, and
mAH capacity ratings and would allow me to charge the batteries while still in the engines.

Tom,

You are right about the inexpensive solar chargers. But I'm planning on putting a bit more coin into my setup. A BP 3125 solar panel puts out 125 Watts for $580. 125 Watts at 12 volts is just over 10 amps. In 4.5 hours it would put over 500 Watts into a storage battery. At 12 volts, that's roughly 40 AH of potential re-charge per day. I'm thinking about starting with two 6 volt deep cycle batteries wired in series, totalling 12 volts. I'm still working on what I need for Amp Hour ratings on the batteries (based on load calculations). But let's assume 120 AH with a maximum discharge of 50% or 60 AH of usable stored juice. In normal days, a battery 50% discharged could be brought back to full charge in 1 1/2 days using the BP panel. I don't plan to run trains that often.

I'll use stored power in the deep cycle batteries to charge the NiMh packs in the engines. This setup should provide more than enough power for that application. What is holding up my design is working through the lighting and pump issues discussed earlier in this post. Thanks to Cale, with the issue of the lights out of the picture, it's really down to the current draw from the pump.
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Response from ConrailRay

I think you should convert part of your pond/stream to a working hydro-dam to replace some of the power.

Our local club is going to build a small layout for a local arboretum and was considering charging a battery from solar power and came across this site: 
www.hightechscience.org/solar_express.htm
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Response from LowNote

This is such a great idea! So I have a couple questions--are you planning to use a solar panel for each charger, or one big solar panel that feeds a bigv battery, which then feeds individual chargers? Whatever you do, please keep us informed. I'm really interested
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My response

Ray,

Hydro-dam? Interesting idea. Are you aware of anyone that has ever done this in scale? No, please don't tell me if you know of one. I certainly don't need another project right now.

Thanks to the link to the solar powered garden RR.

Lownote,

That's an interesting question. If you look back through this thread, my intention was to power lighting, pump and chargers with a single PV system. But thanks to Cale, I'm going to power my 13 path lights with 13 solar units. The verdict is still out on the pump as I can either go with a solar pump or a DC pump tied to my solar setup.

As for battery charging, it makes a lot more sense to me to use a single solar setup regardless of the number of chargers I want to hook up. My railroad will actually terminate in my basement (see following photo) and the charger setup will be down there. I plan to put a solar panel on my roof above the place where trains enter the basement and run the solar CD output lines to the basement where the rest of the equipment will be located.

Everyone,

There are two main kinds of PV systems. The first is grid-tied. The PV solar system is tied to power company power. When a grid-tied solar setup is producing more power than is being consumed by electrical devices tied to the system, excess electricity is sold to the power company. When the use of power exceeds the supply of power from the solar PV system, it is supplemented by power from the grid.

The advantages of a grid tied system are: (1) it doesn't require batteries, (2) all of the power being produced by the solar system is used (locally or by the grid), and (3) the solar system doesn't have to be sized to deal with peak power usage as peak needs can be met with grid power.

The disadvantages of a grid tied system are (1) grid-tied systems do you no good if power needs are nowhere an electrical line,(2) you need to get permission from the power company to hook your system to theirs, and (3) you need to invert the DC power produced by the system to AC to supply it to the grid.

Tying your PV solar system to the grid will probably require professional installation and certainly makes no sense if all you want to do is power a yard light like I'll discuss in the next post.

The advantages of a non-grid-tied system are (1) you can do it yourself as long as you conform to electrical codes, (2) you can have power in locations where running an electrical line could be cost prohibitative (like a Garden RR on your recreational property where you have no grid power), (3) Where the needs are small enough that it doesn't make sense to tie to the grid, (4) Where for moral, personal, or political reasons you want to be totally independent of the grid.

The major disadvantages of a non-grid tied system are (1) you will need to invest in storage batteries as your need for energy often occurrs at different times of day than when the sun is producing power, and (2) you may find yourself in a situation where you will need to overdesign system capacity to deal with peak load needs.

Having said all this, my experimental PV system aimed at powering my garden RR will be a non-grid tied system. In my next post, I'll cover my first step, the least expensive non-grid tied railroad application I can think of. 



The NPC garden railroad will enter my basement staging area through the culvert/window opening in the photo. The charging station, and the equipment for the non-grid tied solar system will be located in this area. The solar panel itself will be on the south-facing roof above the culvert.