Running Electricity Over Long Distance

[mikewj]

My understanding is there is no federal Gov't 'REBATE', but a Tax Credit. Currently it is 30% and may be applied to your taxes over a period of years if you have more rebate than tax due.

[TheYogi]

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Originally posted by mikewj

My understanding is there is no federal Gov't 'REBATE', but a Tax Credit. Currently it is 30% and may be applied to your taxes over a period of years if you have more rebate than tax due.

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You are correct, thank you for catching me on that! []

[chrism]

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Originally posted by TheYogi

Ok, let's take the 7819.5 watt hours and round it up to 7820. Let's say you go with a 48 volt nominal system rather than 24.

7820 / 48 = 162.9 amp hours per day

I'm going to multiply that by 1.2 to account for batter losses, wiring losses, and add a safety factor. These numbers can be calculated much more intricately, but I'm not going to do that and 1.2 is a safe number.

162.9 x 1.2 = 195.5 amp hours

Here is Hilo, Hawaii the worst insolation (daily sun hours) if you're using the wrong inclination, etc according to nrel.gov (http://rredc.nrel.gov/solar/old_data/nsr...state.html) is 2.9 hours per day. We'll use that number to build in additional safety.

We divide 195.5 by 2.9 which equals 67.4 which is your total PV array current in amps.

Now we'd have to choose a solar panel. As an example, I'll use a Sharp NE-165U1 which is 165 watts and is rated at 4.77 amps.

That means we take our 67.4 amp PV array from above and divide it by 4.77 which equals 14.1 or 14 such solar panels in parallel. We aren't done. We take our system voltage of 48 and divide it by the module voltage which is 12. That means we need 4 modules in series. Multiply that by our 14 panels and we find out that we need 56 total panels. Not cheap.

Let's look at battery sizing. We determined our daily amp hours was 195.5. Standard reserve time (how many days of juice your battery bank has) is 3. You can go higher or lower but we'll use 3. So 195.5 x 3 = 586. However, we NEVER want to go below 50% capacity on our batteries or we'll kill them. So we divide the 586 by .5 and get 1173 amp hours. We then choose a battery type. I'll choose a golf cart battery with 225 amp hours of capacity. 1173 divided by 225 = 5.2 which we round up to 6 batteries needed in parallel. Since our nominal voltage is 48 and the battery we chose is 6, then we put 8 batteries in series. We multiply that by our 6 batteries in series and come to the shocking realization that we need 48 golf cart batteries. That means we'd likely go up to L16's which are more expensive but live longer IF you take good care of them.

THIS is why if you're going to be off grid, cutting down on your energy consumption is first and foremost. You need to ditch the guzzlers and get that 7820 watt hour number WAY DOWN.

How much is this going to cost you? I did a QUICK search and a 12kw (you're almost 8kw) system on ebay WITHOUT BATTERIES and a ton of other needed equipment is selling for $41,000: http://cgi.ebay.com/solar-panel-off-grid...RCH:US:101 and that includes 72 solar panels.

If you want to be off grid and not completely break the bank, you have to change your lifestyle.

Disclaimer: My numbers could be wrong. Always work with a licensed professional. Blah blah blah.

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The Yogi.....

THANK YOU!
If you were Jim Cramer I would be giving you a big "Boo-ya, thank you" for taking the time to crunch those numbers!

My wife and I have been going back to your post and reading it over and over all week. We're still finding ourselves looking at each other like a couple of deer caught at night on a dark road paralyzed by the oncoming headlights. It's not that we haven't wanted to post a reply. We're just so "floored" by the numbers.

I don't even think 56 panels would fit on our 3acre lot! (humor)

In reality, we have 3 computers and 2 window shakers (A/C units) and tons of other stuff that we didn't even bother to factor into the inventory I posted. We really thought we were trimming the fat!

My god man!
Tell me there are alternative appliances or websites that will teach us how to live a different way so that we can make the initial cost more bearable! I'll definitely switch to the laptop. That would be a start, but we're just so d#mn floored by your estimate.

With that being said,
Comparing the cost you outlined (and we all know you we're just "guestimating" and really thankful for it!) I'm saying to myself 7 helco poles at $4000-$5000 each comes close to the one-time solar cost, right? So I can try to "reason it away" as if it's kind of a wash. But still either way, it's WAY too much $$$.

An old mentor of mine in the IT sector once said:
"Good, Fast, & Cheep.
You can't have all three!"

I'm sure there's room for a similar saying among the "off-grid" folks out here.

I have images of being a small child walking down a dirt road and dragging my school books on a rope and seeing my mother jamming a stick into a butter churn all day! Do I have to become Michael Landon?

There's just got to be a way to avoid having the "yolk" of HELCO over our head and still have electricity at a reasonable startup price!!
I'm not giving up....[8][]

Again,
A humbled thanks to you, Yogi!
And thanks to everyone for the common sense posts, alternative ideas and advice. It's really great!

Sincerely,
Chris....
Hawaiian Acres

[ric]

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Originally posted by chrism
With that being said,
Comparing the cost you outlined (and we all know you we're just "guestimating" and really thankful for it!) I'm saying to myself 7 helco poles at $4000-$5000 each comes close to the one-time solar cost, right? So I can try to "reason it away" as if it's kind of a wash. But still either way, it's WAY too much $$$.

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Even though the title of this thread requested some discussion of running electricity over long distance, I haven't seen any info on that option . . . it has been skipped over and all this discussion of only solar. I would think the up front cost for long distance run would be still far less than the solar operation. Does anyone have any info on this? Don't we have an option to use 4" galvanized poles also at only about $500 each instead of the treated wooden poles? I could still use clarification on this if anyone knows, but I don't think it would be $4k-5k/pole.

[TheYogi]

Keep in mind my numbers COULD be wrong. I'm no pro, I've just taken about 50 hours of classes. I also like to build in a LOT of safety. For example, 95% of installers would not use 2.9 hours of insolation. They'd use 3.5+

It is indeed a big wakeup call, for myself as well. I took off-grid PV installation classes at the Solar Living Institute in California and remember getting a little sick to my stomach when I realized how much my setup would be if I didn't change my lifestyle. As a society, we're so used to cheap electricity that we don't realize just what an insane amount of it we're using. Then you move to Hawaii where electricity is much more expensive than the mainland and a whole additional variable is added to the equation.

I can't tell you how to change your lifestyle or even what the right choices are for you. However, as someone who is building here in Hawaii and will be doing his own solar install, I can share the changes I'm making.

1. Every appliance we're buying while renting goes through VERY stringent checks. Dehydrator for my partner? 700 watts all day long? No way. Fridge? Either propane or better yet a chest freezer modified to turn off before the freezing point. Or better yet, no fridge at all. Our choice will be the modified chest freezer more than likely.

2. Computers? Laptops only.

3. Anything with a phantom load? Tossed out the window or put on a power strip and turned ALL THE WAY off.

4. A/C? Not happening.

5. Washer? Ok, but we only wash during the day. Dryer? Propane or clothesline or solar kiln.

6. Lots of lights? Nope. We'll be building in tons of natural lighting. In fact, our cabin won't have any electricity. We'll have a separate structure that the solar ties into where we have all the modern stuff.

7. TV? DVD Player? Nope. We can watch stuff we download on the laptops if need be. Or try this fancy thing called reading

Do you have to play little house on the prairie? Not at all. But make no mistake, it takes a big lifestyle change and creative thinking. The funny thing is, I'd wager good money that if you make the change, one day you'll look at your wife and say, "Wow, what the hell were we thinking all those years?"

[David M]

TheYogi - don't know if your numbers are right or wrong, but perhaps your theory needs to be tempered with experience. As I think I've previously stated, I use about 13kw per day. While we practice a number of conservation practices, I also know we purposely use a lot more power than many households, numerous refrigeration,microwave ovens, plasma tv's, power tools, washer, dishwasher, etc . Our system consists of 36 panels @ 125watts each for a total of 4.5kw (non tracking), less than half of your 56 panel/9.2kw system. Except for rainy season, we produce quite adequate power. In the last 22 months, we have run the diesel generator approx 250 hours to augment the sun.

Please keep in mind that propane here is not cheap. I had a neighbor swear by his propane fridge - until he figured the true total cost. Once he had the numbers, it made more sense to add 2 more PV panels to his smallish system and buy a low cost energy efficient Sears unit.

IMHO, over designing a system, based on lack of experience just adds to the problems.

David

Ninole Resident

[TheYogi]

Help me learn David. What would I have written differently if I had more experience?

Thanks.

[Seeb]

ric - try calling delima drilling for a price on setting poles.
even if you have to run a long way helco comes out cheaper per KW in the long run
PV requires a lot of lifestyle change. you cant just come home and flip a switch. especially in the rainy season

[David M]

LOL, doubtful I can be of much help, but you will indeed benefit from your own experiences. Of course, there are a number of other PW ers that have invaluable experience and they graciously share that here. Am glad you didn't take it personally, just a pet peeve of mine to sometimes challenge Building Forum postings not based on hands on Hawaii experience. Note: I suspect your 9.2kw system would cost more than $90K, but that's based on 3 yr old numbers and doesn't factor in possible credits.

I guess I just don't really understand your numbers. Why would someone build a 9.2 kw system to generate 7820 watts (7.82 kw) on a daily basis? If I use your 2.9 hr factor, my 4.5kw system would average 13.09kw/day or 1.67 times the required 7820 watts. This leads me to think that 4 arrays of 4 165w panels (16 total) would produce 7656 watts - near the requirement. My experience tells me I know several off gridders using 8kw/day, but I only know 1 person with a system double mine. Nor do I recall any 48 volt systems with a 48 battery battery bank - I have 12, 1350 AH.

You might also guess, that while I truly advocate conservation and being mindful of usage, I'm totally opposed to the "You too, can have a 3rd world existence while living off grid philosophy".

Keep learning
David

Ninole Resident

[TheYogi]

Hi David,

Thank you for your reply.

Just as you have a pet peeve, I do too. As a PV system designer, I absolutely cringe any time I hear someone say what you have. And I quote:

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Wanna guess the almost universal lament we hear? "Our system was sized too small, we need more panels"...

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Except for rainy season, we produce quite adequate power.

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If I install a system and someone utters those words, that's like me selling someone a truck to pull their boat but not telling them it won't have the power to pull the boat uphill. And the thing is, those words are being uttered on GOOD insolation years. What happens when we have a bad one? The system I design will be fine. The system most installers design will be sucking tanker loads of gas to power the generator. I feel generators should only be used for surges, not as a tow truck for the truck that can't pull the boat over the hill.

As for the 3rd world off-grid living, most people don't have the budget necessary to maintain the lifestyle they're used to. As I don't want to hear them utter the words I quoted above, my job as a PV installer is to help them determine if there is a lifestyle change and PV budget that can they can accept.

As for battery banks, my post stated golf cart batteries. There's no way you'd want 48 of them. You'd definitely jump up to L16's (as stated in my post) which is what I'm guessing you have.