Considering solar power for our cabin

[Shark and Bake Queen]

Hi all,

I am attending the course in a few weeks time and just wanted to get an idea of whether it would be feasible to use solar power when we eventually build, i.e. cost effectiveness and practicallity. We will be building our cabin in Trinidad & Tobago West Indies when we can afford to and the spot where we have our land is exposed to the sun all year round, we have two seasons, summer season for 6 months and rainy season for the other six months, being a tropical country the sun still shines in the rainy season. I know that this is probably out of your jurisdiction but you guys seem to be in the know about these things. Any advice most welcome! :-)

Shark and bake queen, counting down the days to the course and to changing the rest of my life!

[ChainsawGrandpa]

Buy the book; Sunshine to Dollars.
All practical application by an engineer.
No theory, or "Here's what I think you should do."
The book is cheap and there are practical solutions
for solar power.

-Rick

[loghousenut]

Hi all,

I am attending the course in a few weeks time and just wanted to get an idea of whether it would be feasible to use solar power when we eventually build, i.e. cost effectiveness and practicallity. We will be building our cabin in Trinidad & Tobago West Indies when we can afford to and the spot where we have our land is exposed to the sun all year round, we have two seasons, summer season for 6 months and rainy season for the other six months, being a tropical country the sun still shines in the rainy season. I know that this is probably out of your jurisdiction but you guys seem to be in the know about these things. Any advice most welcome! :-)

Shark and bake queen, counting down the days to the course and to changing the rest of my life!


Solar power is easy, affordable and really cool. The real beauty is that you can start with whatever you can afford and add onto your system whenever you care to. Subscribe to Home Power magazine or go to most any good library and peruse old issues. Unless there is some kinda weird tariff issues this one is a no-brainer.

You'll wanna check out solar water heating also.

[rreidnauer]

Solar electric production is only economically effective/practical if grid power isn't immediately available. Nothing comes close to affordable as grid power. But if you don't have it available, and from what I've been learning, I offer a few suggestions. You can start small and build up, but a few things should be followed whenever possible.

1. When you decide on a particular panel, stick with it when adding on. Mixing panels can be done, but it is a pain to efficiently integrate the system.

2. Plan your voltage choice based on the future of your home. Almost all cases will have a growing system, and along with it, an increased bank voltage to overcome cable and system size restrictions. Planning a higher voltage is never a bad idea.

3. Choose good batteries, and care for them like your life depends on it. Like panels, when you choose one, stick with it. You can add on, but it isn't the best thing to do. If you are adding on, only do so by adding a complete string. Don't intermix old with new in a string.

4. Get an MPPT charge controller. They cost more, but squeeze many more watts out of the panels. The cost is easily offset by being able to buy less panels and still get the same amount of watts in a day.

5. And finally, it always easier/cheaper to conserve than it is to produce. Find ways to reduce your energy demands and you'll end up keeping money in your pocket.

[Shark and Bake Queen]

Thanks guys for all you your suggestions I will certainly keep all of this in mind

[ChainsawGrandpa]

Man, you nailed it Rod!

Might also add; "More Power to You" by Skip Thomsen.
The book is based on generator power, but if you have
solar, just also plan on introducing a small generator
system someday. Even if you never have a generator
the book is still worth its weight in gold.

-Rick

[huffjohndeb]

I totally agree with Rod Reidnauer. If you can put in a decent solar system for less or the same amount of moola that it takes to connect to the grid it make perfect sense.

I plan to build using the "Light Green" method if it's green and it saves me green I'll do it. Being green just to be in the in green crowd with no regard for cost is just as bad as the Hummer crowd in my humble opinion.

An example with easy to understand numbers vs. what it may actually cost...
If the solar system cost $12,000 and you can build utilizing the grid, using economically sound practices so that your electric bill averages a $100 a month it would take 10 years to recoup the cost of your solar system. Of course if your batteries only last 5 years and the charge controller dies after 7 years. Then hail destroys your solar array your way behind in the ROI department.

[Shark and Bake Queen]

I will try and get hold to the Skip Thomsen book - I was thinking of generators - thanks

With regard to the cost of solar vs grid, I wont know what the comparisons are until we move back to Trinidad. Our main concern is the course then money to build.....one mountain at a time :-)

[panderson03]

Hello everyone. does anyone know what a good price PV might be? and does anyone know what the average efficiency of the systems are? I read the stats on one system and it said 17%. seemed pretty in-efficient to me!
would appreicate any info anyone can give. thanks very much!

[ChainsawGrandpa]

You can build your own for about $105 / 66 watts.
Look at green power science.com

-Rick

[ChainsawGrandpa]

Here's the link for building your own 18 -20 V,
60W panel

-Rick

http://www.youtube.com/watch?v=5Zy3ELxwdtE&feature=channel_page

[StressMan79]

I don't really like the videos, as they seem to be a chance for "Dan Rojas" to parade his wife in front of a camera (she is easy on the eyes), that and he's kinda a retard, in my opinion. That being said, this video is by far the best I have seen of theirs. Watch it to the end (or where the "bloopers" start), they warn you that it is not really that easy and you have to count the casing costs and time to string them together and seal them.

Put that together with Rod's earlier point about keeping the same panels for the whole project, and you get that you should either do all of them diy or do none of them diy.

Some members believe that the price is coming down. I don't really see that since the value of the US dollar is sliding now and I believe it is on the precipice. Anyway, my advice is to listen to rod. go solar only if cheaper than grid. if you are within 1/8 mile of grid it will generally be way cheaper to go with the grid.

If you decide to go with solar, then make sure you tabulate all the costs, and decide what you want to buy--you'll want to stay consistent on the panels and the batteries (and only buy the latter all at once). $4/watt is a good price, I'd buy them if you can.

[panderson03]

found them for $2.50 a watt! BUY BUY BUY! we won't be stacking logs til summer 2011, but we'll be all set!

thanks again!

[edkemper]

Didn't someone recently find a 45 Watt solar panel for a great price somewhere?

[panderson03]

yeah. I think it was Stressman in 'HF coupon' topic started by Steve.

[dgc]

Speaking of solar panels... I'm a complete n00b at this topic, but I've been trying to read Home Power Magazine and some other things to get up to speed.

I've been formally trained in basic electronics (USAF bomber systems tech years ago), but I'm having trouble getting my head wrapped around the basics of solar calculations. I've printed out my detailed bill showing my usage for the heaviest month of the summer down here in MS (July), and I want to use that info to estimate the costs of replacing the gridpower 100%. Does anyone know a good site that gives some basic configuration examples for us novices to better understand how many panels (varies based on output, I know), what kind of controller/inverter we need, etc.?

DGC

[edkemper]

I'll ne interested in reading what others offer. But I also want to mention that the power use in a log home will be significantly different than a stick built home. But your basic question is the same for me.

[DocJ]

5. And finally, it always easier/cheaper to conserve than it is to produce. Find ways to reduce your energy demands and you'll end up keeping money in your pocket.

An easy way to reduce demand is to walk around your home in the dark (be careful lol) and any item that has a small glowing LED light is an energy drain. Examples might be vcr, cable box, tivo, printers, etc. Read an article that claimed (sorry cant remember the reference) that many of these electronic devices will consume 1/3 the power they use when "ON" in their "Standby Mode". One suggested way to eliminate this power drain is to plug them into a powerstrip or the on/off flip switches to cut off the power when not in use. Just a thought.

[Grey Knight NFO]

Does anyone have good info about the use of Building integrated PV? From what i've seen in the public forums, I'll still need to get a commercial roof put on my home, and I'm considering using an integrated pv system. I haven't seen anyone discuss them and was wondering what the consensus about that route is.

[StressMan79]

with BIPV, you will likely buy your system from the get go, so you'll have a large capital outlay. It is most experts consensus that solar power will decrease in cost in the coming decade, so buying small now and expanding later could save you some dough.
BIPV also determines the pitch of your roof, if you don't want to be constrained by this, you should consider another method.
Even with the right pitch, you can't track with BIPV, so you lose ~20% even when the panels are aligned up and down correctly. If you are building in a tropical location, the up and down variation is not as big of a deal, but in AK, you'll really want to have a 2-axis tracking system.
Finally, the life expectancy of solar panels is not what a good metal roof is (>100 yr). You'll have to buy another roof after 20 years. BIPV is also more expensive than a metal roof.
so in conclusion, I like modular system, but there is nothing terribly wrong with BIPV.

[Grey Knight NFO]

I'm not planning to build within the next decade at this point (I won't really be able to settle down till I retire from the Navy), so I'll have time to accumulate some capital for the investment. I was looking at some bipv that's bonded to a metal roof, which is supposed to currently be able to pay for its self in less than 10 yrs. What I like about that is that I'd still have a roof that would last a century, even if the pv film stops working. I don't like having only one source of power. I'm hoping to use both pv and st for solar and if i find a parcel with flowing water, build a crossflow turbine to harness that as well. The one thing I'm worried about with the bipv is that if TEOTWAWKI happens, rare earth products will become very hard to repair/replace. Current plans are to save up and buy some acres in western MT with cash, and use the trees on the property to build with.
Steve

[StressMan79]

TEOTWAWKI is a major reason for my quest for solar power. Feel free to contact me via my public email. stressman79 @ hotmail dot com.
-peter

[PapaJoe]

http://www.popularmechanics.com/science/energy/solar-wind/4306443

[gaspop]

Might want to pick your brain about a small turbine hydro system at some point if that is included in your experience. Have just guessing about 1800 feet of creek with no more than 300 feet of fall. Best ratio is probably 20 feet of fall in 100 feet We want to limit hour much we remove from the creek and distance. Unfortunately the falls are near the build site. Any ideals on Hydro power.

[rreidnauer]

You are missing one critical factor for an estimate. You need to provide a flow rate.
If I were lucky enough to be able to set up a system, it would be a Pelton or Turgo turbine. This is an all hidden system, since the pipes are buried. It also allows you to stretch your head for vastly increased power output.

[Mosseyme]

Yea I know, the flow is so vastly variable that I need to do a rate at lowest level. With this heat and lack of rain that might be soon. The Pelton is what I have looked at before but it has been a while. My other problem is that the best head is of course where the most waterfalls are and that is at the home site and I don't want the water out of the bed there. The other best sites are a great distance from the final use site and I understand that you lose a lot of your generated power in transfer over distance. It is a puzzle I still have to work out, the most fall, least distance, most water, least impact on the creek bed and my visual peace. I know that it is pricey to put in a hydro system especially if you have enough battery storage to really be successful but at $7 a foot a couple of years ago and at least 2500 feet of buried cable we are thinking it would pay in the long run to stay off the grid. We are so deep in the valley between mountains that solar power would probably not give us enough as primary power. Wind system would have to come off the ridges and several hundred feet of cable. So we have water, have to figure out how best to use it. Have to peel logs first!!!

[Grey Knight NFO]

Since you have falls, I'd suggest a pelton, which will give excellent results in a low flow/high head situation. (of course, get an accurate measurement of flow and head and either do a lot of homework on hydrodynamics or hire someone who has to design/install it). To reduce line loss on its way from the turbine site to homesite, use an ac generator and as high a voltage as possible. Since Voltage = Impedance (Resistance) X Amperage, you can make a direct trade of volts for amps without loss of power. More amps require larger wires and leads to larger line losses from resistance. Also, without going to far further into the weeds, AC is more resistant to line loss than DC. Therefore, generate your power in AC, step it up as high as you dare, and you can send it further over smaller lines with less loss than you could with low voltage DC. Once you get it to the battery bank, (which i would as keep far away from water as possible), it'll be simple to step down to the voltage you need and then rectify it to DC for the batteries.

-Steve

[PapaJoe]

I have not experimented with "generating" energy with flowing water, rising water, etc., but I have "saved" energy using water pressure from my well. Example; If you have a basement with an electrically operated sump-pump consider opererating the pump with your already existing water pressure. The extra bonus of reliability and non-electrical power reliance is what originally attracted me to this system. Go to this web-site to see how ... <a href="http://www.radonseal.com/pumps/water-powered-pumps.htm">http://www.radonseal.com/pumps/water-powered-pumps.htm</a>
Here are a few links that address generating power with flowing, rising and falling water, etc.
<a href="http://www.absak.com/library/hydro-power">http://www.absak.com/library/hydro-power</a>
<a href="http://www.alternative-energy-news.info/technology/hydro/">http://www.alternative-energy-news.info/technology/hydro/</a>
Best Regards,
<a href="http://www.radonseal.com/pumps/water-powered-pumps.htm"></a>

[rreidnauer]

Yea I know, the flow is so vastly variable that I need to do a rate at lowest level. With this heat and lack of rain that might be soon. The Pelton is what I have looked at before but it has been a while. My other problem is that the best head is of course where the most waterfalls are and that is at the home site and I don't want the water out of the bed there. The other best sites are a great distance from the final use site and I understand that you lose a lot of your generated power in transfer over distance. It is a puzzle I still have to work out, the most fall, least distance, most water, least impact on the creek bed and my visual peace. I know that it is pricey to put in a hydro system especially if you have enough battery storage to really be successful but at $7 a foot a couple of years ago and at least 2500 feet of buried cable we are thinking it would pay in the long run to stay off the grid. We are so deep in the valley between mountains that solar power would probably not give us enough as primary power. Wind system would have to come off the ridges and several hundred feet of cable. So we have water, have to figure out how best to use it. Have to peel logs first!!!
Several things. Hydro is great because, unlike solar and wind, it generates 24/7, so you can get away with a much smaller system for equal monthly kWh's. Also, a piped Pelton/Turgo has the advantage of regulating flow, whereas you don't have to use up all the creek's waterflow, or tie up up beautiful waterfall with a low-head system. This is one reason I recommend to folks to extend their penstock as much as financially possible for maximum head pressure, because then you can reduce volume since you trade off for more pressure, thereby leaving more water to continue naturally down the stream. You don't even have to disturb the stream to any great degree. Probably the trickiest part would be establishing the intake, and I think I have an idea on how it could be done without even digging the pipe into the stream bank.
Other than cost, distance issues are easily dealt with. Losses in a piped system are a function of water velocity. The faster water flows through a pipe, the more pressure loss you'll have. To slow the velocity, you simply increase pipe diameter. Just doubling the diameter of a pipe increases area by a factor of 4, so flow rate is 1/4 the speed by simply going from 2" to 4".
I downloaded this calculator (http://www.energyalternatives.ca/Downloads/MicroHydroCalc.exe) several years ago which let's you run numbers for a system. It's nice because it can let you calculate flow rates depending on pipe size, length, and head. It gives you an idea of what you can do with what you have to work with.
You should really try to determine the flow rate of your stream. To do this you should find a fairly uniform portion of the stream, and determine the area it contains. (depth and width in feet) Toss a little something that floats and time how long it takes to traverse a measured distance. With that, you can multiply the area with the measured distance to find volume, (width * depth * distance * 7.48 = gallons) then calculate in the timed period to calculate gallons per minute. (volume in gallons / timed seconds * 60 = GPM) I have no idea how big your stream is, but you might be surprised that you only need a small portion of the creekflow to run a turbine. It's quite easy to underestimate just how much water is flowing past just by looking at it.
I'd love a chance at building a system for someone. I'd think it'd be a lot of fun.

[Mosseyme]

Thanks for all the info, I'll have to sit down and digest it a bit to understand. They didn't include these calculations in my nursing studies but I have been learning the basics. If you lived close enough maybe we could hire you to build this when the time came. You did change my thoughts on one thing, I had thought the idea was to make the water fall faster, and with less resistance until it hit the turbines. So much for what I know. My old brain can only focus on so many things at a time and I have just been keeping this one on the perimeter until the time came to need it.