TalkBaja.com » Baja Mexico Forums » Off-Grid / Solar, Wind or Generator?

Ok, I'll start this thread. I became interested in solar more out of need than interest. We're building quite a distance from any resources, so I thought it would be in our best interest to learn about solar and install it ourselves. First step was to determine how much power we would be using. To calculate power use, we needed to figure out exactly how much energy each appliance and light uses, along with how often they will be on. This information can be found on the back of most appliances. The easiest way to find out power use is to buy a Kilowatt device (amazon.com) and plug each appliance into it to find out how much power it draws.

To make the calculations easier to change as we expand our home, I developed an Excel spreadsheet to calculate our total energy needs. The spreadsheet below reflects our future anticipated energy needs. In our application we plan to use 24v 175 watt panels and 12v 212 amp batteries, but the spreadsheet can be changed to accommodate other size panels or batteries. I don't guarantee this thing is totally accurate, but it has worked well for us (so far). I used it to calculate our current system (which is much much smaller) and it has kept well ahead of our power use.

You'll note in some cells, there are no values for a given light. These are lights that would be turned on only after some other light I've already entered a value for has been turned off, or they are lights that I don't anticipate using much. Some entries are in fractions of hours like .16. These are appliances that will be used only a few days a week, or for some time less than .5 hrs/day. To calculate for appliances used a few times a week, I took the total anticipated watt usage per week and divided by 7 to get a daily figure.

If anyone wants to use the spreadsheet, it's located below. You might need a basic understanding of Excel to use it. There are three tabs at the bottom. One for DC power calculations, another for AC calculations, the the third gives the final results. To adapt if for your use, just replace the location/appliance descriptions I've entered with your own, then delete the ones you don't need. Then re-enter your own values for watts and time used, again deleting the values in the cells you don't need. It will automatically calculate the final values. For this to work properly, only change or delete values in the "appliance/location", "watts', and "hours used" cells. Don't change anything else or it won't work. Also don't add values into cells that are currently blank, they may not be added into the final value.

OK, I have downloaded your spreadsheet and am working on that. I would be interested in seeing any photos you have of your setup / equipment / battery storage, etc. Are you using only solar power or are you using wind as well? If not did you consider that? Another question I have is what do you do in prolonged periods of cloudy/overcast days? Do you have a generator backup and if so, what size?

Lots of questions I know, but any help is really appreciated!

Originally Posted by BajaGringo

OK, I have downloaded your spreadsheet and am working on that. I would be interested in seeing any photos you have of your setup / equipment / battery storage, etc. Are you using only solar power or are you using wind as well? If not did you consider that? Another question I have is what do you do in prolonged periods of cloudy/overcast days? Do you have a generator backup and if so, what size?

Lots of questions I know, but any help is really appreciated!

We are using solar only right now, but we don't have the extended low-cloud days like you probably do. We do, however get a lot of high cloud cover in the winter. We don't have a generator backup yet, but our current house is only 650 square feet and we don't have any critical systems that require power. If there's clouds we just conserve power, less light use at night, no movies and cut computer use. Our fridge is currently propane.

I would like to add wind generated power, but the affordable propeller type wind turbines are very noisy. I could put it far enough away from my house that I couldn't hear it, but I think it would irritate my neighbors so we aren't planning on wind right now. I do want to explore some of the new technology though that doesn't use propellers and is much quieter.

When we start construction of our main house we'll expand the solar and add a generator. Our main house will have an AC refrigerator and separate AC freezer so it will be more important to have backup power. If we have family or friends staying and using extra power, or we have long cloudy periods, we'll have to supplement with the generator. I plan to have enough battery storage to endure two full days of clouds before having to use the generator.

I've heard a lot of good things about the Kohler generators. They seem to be very quiet and reliable. We're planning on somewhere between 9 and 12KW. I'm going for a larger generator to cut down charge/run time (less irritating), plus I have some tools that require a bit more power than my inverters can provide. If you don't have any large tools though, and don't mind longer run times, a 3 to 5KW generator would work just fine. For the smaller size I think the Honda's are probably best.

Originally Posted by BajaGringo

I would be interested in seeing any photos you have of your setup

Outback has some real nice/clean integrated systems where everything plugs together on a single unit, but they're very expensive. The advantage is all you have to do is mount it and make some external connections. It uses much less space and you don't have all the conduit runs like I do. They are also very pricey, so I opted to use separate components. I saved several thousand dollars this way, it's just not as clean looking and requires a lot more work. This isn't current, but it's the most current photos I have:








I opted to avoid mounting on the walls, instead I used a "Gorilla Rack". Reason I did it this way is that we had a neighbor who mounted all his components on the wall, we had a large wind driven storm and water found it's way down the walls and shorted out all his equipment. Huge $$ loss. Eventually there will be another rack to the right the will house the additional batteries.

We used AGM batteries because they don't require maintenance and don't require venting. The cost has gone up so much for these batteries though, that if I were starting over I wouldn't use them.

This would probably make a real electricians head spin, but here's a wiring diagram I made so I could remember what I've done:

I for one am impressed. It looks like a well thought out system.
Your documentation of the wiring is very well done.

Sooner or later the system will need repairs/maintenance and having the diagrams will save a lot of headaches and time trouble shooting.

Wow!

Thanks so much for the detail and photos. This really helps those of us at the stage of figuring out how to get where you are. You have definitely given me a lot to think about and I am still digesting some of it. One question I have is about the refrigerator. I was looking at whether to go electric or propane and I noticed that you mentioned you currently have propane but will go to electric in the main house. Did you consider just going with a larger propane fridge? I am still not 100% sure which way we are going to go and am looking into the pricing and options out there. I am definitely thinking we will use wind power as well and would be very interested in sharing ides with about different technologies and sources that you are looking at. One thing I have noticed is that there are a lot more sources of wind generators available and hopefully we can find the right mix of generating power - noise - cost. It seems like out where we are at there is always wind on days with little or no sunshine so it just seems like a logical way to go...

Another thing you made me consider was to now keep my server rack. I have used an old Compaq server rack to house my music server. Yes, I know - I am a music nut but we'll save that for another discussion - ha! I am designing a different type install for my gear in the new place and was going to leave the server rack behind. Now you have me thinking about bringing it along and figure out a way to turn it into a power control rack. I have a big old Sola isolation transformer I could wire in to protect my most sensitive gear.

Back to the drawing board...

:idea: :idea: :idea:

Originally Posted by BajaGringo

Wow!
One question I have is about the refrigerator. I was looking at whether to go electric or propane and I noticed that you mentioned you currently have propane but will go to electric in the main house. Did you consider just going with a larger propane fridge? I am still not 100% sure which way we are going to go and am looking into the pricing and options out there.

I like our propane refrigerator, it works well and we thought about buying a larger one (we have the smallest "full" size Servel fridge) but they do use a fair amount of propane. I think you're probably in a similar situation to us in that you have to haul your propane bottles to get them filled? We don't have a local service that delivers, so the less I have to haul those bottles, the longer my back will last .

I think over time, the additional investment in solar to run a 120v fridge will pay off in both $$ and convenience. If we were in a situation where CFE might install power in the near future, I might not make the additional investment, but I don't see us having power in the near or distant future so I think it makes sense.

If you go to the energy star website you can look up refrigerators and how much power they use. Unfortunately they give the power use in Kilowatts per year, but I just divide that by 360 to get an average daily figure. Just to be safe I add 10% to that for my calculations. There are some energy star products sold in Mexico, but if you want the ones that are super efficient, I think you still need to get it in the U.S.

Originally Posted by BajaGringo

I am definitely thinking we will use wind power as well and would be very interested in sharing ides with about different technologies and sources that you are looking at. One thing I have noticed is that there are a lot more sources of wind generators available and hopefully we can find the right mix of generating power - noise - cost. It seems like out where we are at there is always wind on days with little or no sunshine so it just seems like a logical way to go...

Yes, definitely... wind will be in our future somehow. If not now, definitely later. We don't lack wind. It would allow us limit generator use to cloudy/windless days which don't happen often. There was a good thread on this in Baja Nomad recently, here are some links:

http://www.windside.com/old/models/models.htm
http://www.pacwind.net/products.html

There's some good stuff out there now. We haven't purchased anything to expand our system yet but before we do, we'll definitely do some more research on wind. What I like about some of the windmills on these sites is they can be mounted to the building as the wind turbulence caused by the walls doesn't affect them. They're also quiet, but they're also very expensive.

My main concern with wind is being considerate to my neighbors. We'll all be running generators once in a while, but a windmill can be an eyesore and if it's noisy it'll be making noise all day and night.

Originally Posted by expat

I for one am impressed. It looks like a well thought out system.
Your documentation of the wiring is very well done.

Sooner or later the system will need repairs/maintenance and having the diagrams will save a lot of headaches and time trouble shooting.

Thanks Expat.

Off grid solar is all about money. The more power you use, the more expensive your system will be.

If you want to keep power use and cost down, here are a couple things I've learned:

If you decide to go solar, compact fluorescent and L.E.D. lights are the way to go. If you use regular incandescent bulbs, halogen, or any other high power lighting your power use will be through the ceiling. So plan on using fixtures that incorporate L.E.D. or CF

It's also important to install additional switches to isolate lighting more than usual. For instance, if your dining and kitchen share the same room, don't have one switch turn on the kitchen and dining room light. Install a switch for each and put it in a convenient place to use. That way you don't need the have the kitchen light sucking battery power while you're eating. If you have more than one entrance to a room, install switches at each door so you can turn the light off when you leave no matter what door you use. Determine your paths of travel within your house and install switches accordingly so you can turn lights off as you leave a room.

TV's, stereos, appliances with clocks use quite a bit of power over a 24 hour period, when they're off. Install a power switch to the outlets that will supply this type of equipment so you don't have to constantly be unplugging them to conserve power. Turning these off when not in use can save on having to buy extra panels and batteries to support their "phantom" loads.

Install 12 volt lighting in your utility room. That way if you need to work on the inverter your batteries will still provide lighting.

Install the ceiling fan switch in the bedrooms near your bed. Fans use quite a bit of power and when it's not needed, you won't get up to turn it off. If the switch is by the bed you will be more inclined to turn it off when you don't need it and will be able to conserve more power.

Really great stuff you are giving us here. I am a bit in no-mans land yet as they keep teasing us with the idea that we may have CFE out in the not to distant future. Many have told us we are nuts but I just discovered yesterday the reason why that in fact, may actually happen after all. It turns out the Rodriguez family which own Los Pinos, a very large farming company here in Baja as well as folks close to the governor himself have property out there as well. So Power lines may in our future after all.

Even if we get power next week however, I still want to have a backup system at minimum that I can power some lighting, fridge, computer, etc just in case when the winds knock out the power. I just need to know how much capacity to build into it...

Originally Posted by BajaGringo

Even if we get power next week however, I still want to have a backup system at minimum that I can power some lighting, fridge, computer, etc just in case when the winds knock out the power. I just need to know how much capacity to build into it...

If all you need is backup power, here's another option:



We have a condo in Nicaragua where the power goes out often during the rainy season thunderstorms. We needed something so we could at least have ceiling fans, a few lights and keep the fridge going when the power goes out. This is an inverter/charger. It connects to the domestic AC. While the power is on, it keeps the batteries charged, then when power goes out, it automatically switches over to battery power and converts the 12 to 120V. When the power goes out you never even notice the changeover. When power is restored it automatically switches back and begins recharging the batteries.

Waaaaaaaay less expensive than using solar panels if all you want is backup power.

In that setup are you running 6 volt or 12 volt batteries?

Originally Posted by BajaGringo

In that setup are you running 6 volt or 12 volt batteries?

They're 12v batteries wired in series to 24volts. The charger is 24 volts . I really didn't need a 24 volt charger as my wire runs are very short, but it was the only decent charger I could find down there.

Why do I keep hearing that it is best to run 6 volt batteries then?

Originally Posted by BajaGringo

Another thing you made me consider was to now keep my server rack. I have used an old Compaq server rack to house my music server. Yes, I know - I am a music nut but we'll save that for another discussion - ha!

Hey baja gringo - you really use that thing for music in your house or are you just pulling our leg? Looks like something out of a Buck Rogers movie.

Yes, I really do have that for my music setup. Almost a 1000w RMS. You haven't even seen the speakers. I can rattle dishes a block away. Every once in awhile I will get crazy and put on something from back in the day - Boston, Kansas or Jethro Tull.

Just my way of checking to see if the neighbors are still alive...

Originally Posted by k-pasa

Why do I keep hearing that it is best to run 6 volt batteries then?

In the past, by combining two 6 volt batteries, you cound get higher amperages than with one 12 volt battery. Battery technology has improved so much that I'm not sure thats so true anymore.

I have visited several websites that still preach the 6 volt philosophy. Maybe they are behind the times...

Originally Posted by BajaGringo

I have visited several websites that still preach the 6 volt philosophy. Maybe they are behind the times...

I really don't know for sure which is better. For our system, using AGM batteries, it was about 100 dollars less expensive to use 6 volt, but the down side of 6 volt was there were more batteries and cables to install, and for the same amp storage capacity, 12 volt required less space. 12 volt wound up being a much easier and cleaner installation.