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

While up visiting Mike (astrobaja) the other day we had a brief conversation on panel orientation and I have had it on my mind ever since. Most sources tell you that if you aren't on a tracker it is best to face all of your panels due south.

The more I do this off-grid stuff I am learning that not all the "common knowledge" on the subject is necessarily correct for all applications, especially off-grid and even more particularly - Baja Off-Grid. I have been looking into a tracking system but the more I think about it I am becoming concerned about the times of year where we experience really high winds. It is windy here all the time which is great for my wind turbine but I am now thinking that I am just asking for trouble with a tracking system. My guess is that they will probably work better on the east side of the peninsula where they enjoy good sun and less wind.

The problem with just facing them all straight south is that it is truly not optimal in my mind for our energy needs. Most topic related forums that tell you to do so are run by folks dreaming of watching their electric meters spin backwards via harvesting as many kW a day as possible on grid-tie systems.

Those of us off-grid with battery storage learn that if you have the correct balance of panels - batteries - loads that at some point in the day your charge controllers will be throttling back on the panels to keep them from overcharging the batteries. Unless you set up a diversion controller to sell the excess to a neighbor or some other application, those excess amps are lost.

If you don't have a tracking system the panels begin to lose sunlight and charging capacity in the later afternoon, just about when your energy usage starts to increase.

This has lead me to re-think my panel orientation. I have two Xantrex XW-MPPT controllers and I am strongly considering splitting up my panels into two, 1 kW arrays. The first set of panels oriented S-SE to catch the early morning sun to get the batteries up and running early. That orientation should catch good rays at least through lunchtime.

I would then setup the second set of panels facing almost due west. That array will pick up sometime mid morning and keep delivering high amps until late in the day, taking advantage of the sun reflecting off the ocean, which I have read will increase the sun light intensity. Those extra amps delivered to my batteries later in the day will help offset the early evening loads around dinner time.

I may be way off base but the more I think about this it just keeps making sense to me. Anybody here see a big error in my plan???

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How many overcast mornings there?

I bet most are in the spring/summer when the arc is high. Then in the fall/winter when there are a lot of clear mornings, the sun is way low towards the south.

Instead of a tracker, how about some kind of pinch bolt setup that would allow you to pivot the array on a pole? That way you could make a relatively-easy adjustment when you detect a weather trend of several days/weeks.

Splitting the systen sounds ideal to me. There was a guy up here that had one of those heat seaking things ,when you drove past in the car it would follow you.I guess he must have spent a ton of money on the system.He and his wife got tied up and robbed and they left The house now has electricty and the heat seeking pannel looks pretty much like junk now.

Originally Posted by Marty Cortez

How many overcast mornings there?

I bet most are in the spring/summer when the arc is high. Then in the fall/winter when there are a lot of clear mornings, the sun is way low towards the south.

Instead of a tracker, how about some kind of pinch bolt setup that would allow you to pivot the array on a pole? That way you could make a relatively-easy adjustment when you detect a weather trend of several days/weeks.

We get pretty good charge (50%+) on cloudy mornings with our mono-crystalline panels so that doesn't seem to be an issue. Any system that puts all our panels on a pivot-able pole will face the same problems with the wind. I am going to make the new panel installation height angle adjustable though to allow for the change in the suns pass based on season...

Originally Posted by J.P.

Splitting the systen sounds ideal to me. There was a guy up here that had one of those heat seaking things ,when you drove past in the car it would follow you.I guess he must have spent a ton of money on the system.He and his wife got tied up and robbed and they left The house now has electricty and the heat seeking pannel looks pretty much like junk now.

Yikes!

Everything I've read about fixed panel orientation says true south is best. Here's a chart to help you figure "true" south: http://www.geo-orbit.org/sizepgs/mag...l#anchor598933

All mine are facing "true" south because "everyone" says that's best.

Now...does that really mean true south is best for every situation? Who knows? My neighbor has two panels on a palapa over his travel trailer. One is on the east slope and the other on the west slope. He swears it charges better than having both facing south, but he didn't really experiment to see if it actually is. We have mega ocean glare for a few hours in the morning as the sun comes up. If ocean glare increased panel output, that may account for why his panels work better with one facing east.

Do you have the ability to isolate and change a couple of panels to see if they charge better before committing to a more permanent rack in those directions?

Since mine are mounted on a flat roof, I have the ability to change the tilt angle seasonally also. At our location the best angle for summer is about 5 degrees to the north, spring and fall, 17 degrees to the south, and winter 35 degrees to the south. I don't have the ability to do 5 degrees north, so I put them flat for the summer months. I just adjusted from flat to the 17 degree fall tilt setting about a week ago. Changing the tilt bumped my total output about 3 amps. Not that exciting, but it did make a difference. I don't change from the fall setting to the winter setting though as our winter energy use is much less than summer/fall so it's not worth the hassle of changing the tilt again.

Here's a site to determine tilt angle for your location: http://www.macslab.com/optsolar.html

If you decide to experiment, it would be interesting to see which orientation is best. I looked online to see if someone had tried, or documented a comparison, but couldn't find anything.

When you dive into the discussion on orientation you have to be careful to differentiate between just trying to get the maximum hours of sun on your panels to when your batteries need to get the most amps.

Woo - have you looked closely at your Outback during the day? Take a look at what the amps are doing when it goes into float. Even though the sun is still pounding down because your panels are facing optimum direction, the amps are cut way back to keep the batteries from overcharging. What happens around 6:00 PM this time of year? I'd be willing to wager your Outback goes back into Bulk mode but now struggles to keep your batteries anywhere near 13.5 volts this late in the day as the amps just aren't there, right?

That is when you are making dinner, turning on the TV and could really benefit from some west facing panels...

I have been logging the current setup and once I make the change I will post the results. Off-grid you just can't look at total kW a day, it really comes down to our batteries and that is what I see as the benefit of this change in philosophy.

By the way - the wind turbine has been kicking ass...



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Disclaimer- I know little to nothing about off-grid power needs. That said, what I do know about the San Quintin area is that wind generation has to kick butt. Likewise, San Quintin is located in one of those Pacific Coast areas that is subject to a strong marine layer. NOB, and I'm sure BG can attest to it, there is a major difference in direct sunlight between Carpinteria and Santa Barbara. As I said, being mostly ignorant on this topic, just a face in the crowd, I'd think that more reliance on wind and less on solar, would fit into the San Quintin climate. That said, I'll go away now.

But, many years ago, I was living in Agoura. We installed solar panels on the roof. Given, that back in the day, the technology was primitive. But what it gave us, was hot water and a family room that remained toasty in the middle of winter, without having to resort to using the furnace. Nowhere close to living off the grid. Just call me tenderfoot. And now, I'll go away.

Originally Posted by Bajahowodd

Disclaimer- I know little to nothing about off-grid power needs. That said, what I do know about the San Quintin area is that wind generation has to kick butt. Likewise, San Quintin is located in one of those Pacific Coast areas that is subject to a strong marine layer. NOB, and I'm sure BG can attest to it, there is a major difference in direct sunlight between Carpinteria and Santa Barbara. As I said, being mostly ignorant on this topic, just a face in the crowd, I'd think that more reliance on wind and less on solar, would fit into the San Quintin climate. That said, I'll go away now.

But, many years ago, I was living in Agoura. We installed solar panels on the roof. Given, that back in the day, the technology was primitive. But what it gave us, was hot water and a family room that remained toasty in the middle of winter, without having to resort to using the furnace. Nowhere close to living off the grid. Just call me tenderfoot. And now, I'll go away.

I was a total novice a year ago and have been working hard to get up to speed. A lot of this is common sense and you obviously understand many of the issues that we deal with in our system setups.

We do get a marine layer here - this summer has been a bad one. I have found that the mono-crystalline panels on the house that make up the bulk of my array seem to do a much better job of charging in the gloomy weather than the poly-crystalline's on our RV. That having been said it is really nice having the wind turbine churning out amps after the sun goes down. I can run my electric fridge, exterior lighting and 50" plasma TV watching blu-ray and not worry that my batteries will over discharge.

I like it so much I am going to be installing a second turbine in the coming weeks...



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Originally Posted by BajaGringo

When you dive into the discussion on orientation you have to be careful to differentiate between just trying to get the maximum hours of sun on your panels to when your batteries need to get the most amps.

Woo - have you looked closely at your Outback during the day? Take a look at what the amps are doing when it goes into float. Even though the sun is still pounding down because your panels are facing optimum direction, the amps are cut way back to keep the batteries from overcharging. What happens around 6:00 PM this time of year? I'd be willing to wager your Outback goes back into Bulk mode but now struggles to keep your batteries anywhere near 13.5 volts this late in the day as the amps just aren't there, right?

That is when you are making dinner, turning on the TV and could really benefit from some west facing panels...

I have been logging the current setup and once I make the change I will post the results. Off-grid you just can't look at total kW a day, it really comes down to our batteries and that is what I see as the benefit of this change in philosophy.

By the way - the wind turbine has been kicking ass...



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At 6:00 pm with the freezer working overtime because of the heat, two ceiling fans running on high, two computers on, and the sat internet drawing about 50 watts, my use is about a negative 8 amps. My controllers are in what's called mppt float mode, whatever that is. Yes, they're struggling to keep up at this hour.

It will be interesting to see the results of your change in orientation. The thing I would be most worried about is making sure that you're getting enough solar input during the peak hours of the day to assure your batteries absorb properly. My batteries need to absorb at 14.4 volts until the absorb amp output drops to .5amps per every 100 amps of battery storage, which is about 3 hours.

The amp output in absorb drops significantly compared to bulk though, so not having all your panels facing true south may not make a big enough difference to impede the absorb process. Once you make the change, I'd keep an eye on it to be sure you stay in absorb, at the proper voltage, until your battery absorb specs are met.

I'd love to do wind, but I think my neighbors would string me up if it made too much noise.

You are totally correct about having enough panel output to go through the bulk/absorb stages in the morning - I think I am OK now but to be sure I am shopping to buy some extra panels now.

One comment I get from everybody who comes over now is that they are surprised at how quiet the wind turbine is. Today we had winds over 20mph and I never could hear it...

Or maybe after years of loud music I am deaf???




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When I first started off grid I had a fixed array, and went through the same questions you are going through. Where I am at I have some hills to the east of me and some mountains to the west. What I found that worked best for me was not due south but solar noon. in other words I aimed the panels at where the sun was at its mid way point accross the sky. That woked pretty good. Then I built a pole mount for my panels, and I was able to rotate them a couple times a day to aim them at the sun. About 4 years ago I built a 2 axis tracking mount for my array. The only really tecnical part of the whole project was the sun sensor, and it turned out that it was the easiest and cheapest part of the whole system. Now my array produces about 40% more than when it was fixed. When the wind comes up I just lay the panels flat so they are at their least wind resistant position. My panels put out 72 amps right up to when the sun goes behind the hill, in the winter that happens at about 3 pm.
Your system looks like a well thought out and funtional system that fits your needs and what your location offers in the way to produce power. I suspect t wil last you many years.
Larry

WooHoo!!!

I just picked up four, 240 watt LG panels for $1500. I am thinking that I will just put these on a dedicated controller and make them my west facing panels. They should be pulling some good amps right to sundown...



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