Ken Hall's posts

Posted by Ken Hall on May 7, 2009 10:52 am

#61 -  Renewable Energy > RE General Discussion > Re: Swamp Cooler Conversion to 12 volt DC
Do you want the same performance that you are currently getting ?
You have a 700 watt motor. If you go with less than that, it will cut down on the air flow. That will mean less cooling.
How many hours a day do you run the thing ?
If you run it 4-5 hours, you are going to need about 700 watts of panels (not counting losses).  If you pay 4.50 a watt for panels, you are looking at about $3150 in solar panels. 

Whether you use an inverter or go straight 12V, the 700 watts would be 60 amps on the 12V side (without inefficiencies or losses.)

Posted by Ken Hall on May 2, 2009 02:23 am

#62 -  Renewable Energy > Technical Discussion: Other > Re: Wind Turbine wire size
Here is a calculator that I find more useful. It is good for both ac and dc.


Posted by Ken Hall on May 2, 2009 02:07 am

#63 -  Renewable Energy > Technical Discussion: Other > Re: Solar for RV
I do not know why you presume to have the right to lecture me on my English usage (or whatever the hell you want to call it.) 
“The article can't be persona non grata because the article isn't a person.”

Did you see the quotation marks around the phrase Huh
Just for your information, one of the proper uses of quotation marks is to signal unusual usage of a word or phrase.  If you are going to call someone on something, you better be right.

What a pompous, arrogant, north end of a southbound horse.

Posted by Ken Hall on May 1, 2009 03:13 pm

#64 -  Renewable Energy > Technical Discussion: Other > Re: Solar for RV
I don’t see why Fred thinks that  Handy Bob’s articles would be “persona non grata around these parts”. There is a lot of good info in them, but it has the danger of being mis-used.

Handy Bob has a disrespect of RV dealers/solar sellers around Quartzsite AZ, not of all people in the solar business. Fred seems to apply a similar disrespect to everyone in the solar business.

Solar systems in RV’s while being similar to residential systems, do have different aspects that you need to consider. And conversely, you cannot apply “what works best for RV’s” to all PV systems.

Golf cart batteries are the entry level batteries of the solar business.  They could even be called the bread and butter of the small system. But for larger systems, they are just training batteries.  There are a lot better batteries out there, particularly for larger stationary systems.

Charging at 14.8 is Trojan’s recommendation; it is not the gospel for every wet cell batteries. Interstate recommends a bulk charge setting of 14.4. 
Note that Handy Bob mentioned a battery temp sensor. While I like them for all installations, they are even more important in RV’s. And, if you are charging above 14.4 volts without one, you are living dangerously. The warmer the ambient conditions, the more important the sensor is. I’ve gotten to the point where I no longer consider them optional.

Wire sizing is important. I generally aim for 3 percent drop or less. It is also important to consider future upsizing of the system. I weigh the cost of going larger now vs. the cost of future rewiring.  But “bigger is not always better”.  #6 and #8 are SMALL wires with a marginal cost difference. Look at the price difference in a 1/0 and a 3/0  before saying bigger is better. Carte blanche oversizing wires can be a huge waste of money.

But the point that I really differ with these gentlemen on, is the value of the MPPT controller.  If you live (or RV) in an area with great solar conditions, you may not see great value in it.  But, where you will see the value of it is in less than optimal conditions. It shows gains in the hours before and after the peak sun period. If you have any type of overcast, marine layer, smoke, smog, dust, etc, that reduces the solar insolation, you can have a boost even during the peak sun hours. 

In my area, I usually see a summertime increase in production that is close to 10%.  Over in the fog belt (closer to the coast) it is closer to 15%.  We never get the 30% boost that the mfgs claim for wintertime, primarily because we don’t have subfreezing, crystal clear winter days. You can count the days below 40 degrees on one hand.  MPPT is not “only useful in winter”.

You do have to try to quantify what this increase is for a particular microclimate, and weigh the value of it. The best way to do that is install one on an existing system with known production and then compare the difference in monthly production.  In my area, it is a no brainer. Yes, it costs more. But it is a lot cheaper than increasing your array by 10%.


Posted by Ken Hall on Apr 28, 2009 05:43 pm

#65 -  Renewable Energy > Technical Discussion: Other > Re: Solar for RV
Ken (nice name):
I am with James. Wire the panels in series for 24V.
Not only is there no advantage to wiring in parallel, in some lighting conditions it would be a distinct disadvantage.

I am happy to see that you are considering are going for temp sensor. I like them for all systems, but they are even more necessary in an RV situation.


Posted by Ken Hall on Apr 26, 2009 11:08 pm

#66 -  Renewable Energy > Technical Discussion: Other > Re: Wind Turbine wire size
#10AWG is rated at 30amps for 120VAC.  You hit the 5% voltage drop at about 100 feet. For 12VDC and 12.5 amps, it is good for about 24 feet.
The 40 amps for #8 is also a 120VAC rating.

You need a #6 AWG to carry 12.5 amps 53 feet at 12VDC. It would yield a 4.48 percent voltage drop according to my calculator.

Is the 53 feet the entire run including the vertical drop from the turbine ?  Or, is it the horizontal distance between the tower location and the batteries ?


Posted by Ken Hall on Apr 25, 2009 11:45 pm

#67 -  Renewable Energy > RE General Discussion > Re: Airbird Wind Turbines

Thanks for posting your results.  I do appreciate you taking the time to do so. 

I hope things are fairing well for your niece.

Take care,

Posted by Ken Hall on Apr 25, 2009 12:58 pm

#68 -  Renewable Energy > Technical Discussion: Other > Re: System requirements
The fact that the Mfg put a 20 amp plug on it means that that he wants it on a 20 amp dedicated circuit. It generally indicates that the machine will draw better than 15 amps for a period long enough to trip a 15amp breaker. Depending on how much and how long it exceeds the 15 amps, it could possibly damage the kill-a-watt. They are only rated at 15 amps.
Even with a Watts-up, which can handle 20 amps, you need to get cords rated for 20 amps, not the 15amp cords that it generally comes with.
Using adapters to sandwich a 15 amp device between a 20 amp source and a 20 amp load is risky business. If you do it, you had better hang around and watch it. Feel the cords for excessive heat, etc. Do not leave it unattended.

Posted by Ken Hall on Apr 24, 2009 11:57 am

#69 -  Renewable Energy > Technical Discussion: Other > Re: How to find the tilt factor for a given tilt angle

Posted by Ken Hall on Apr 24, 2009 11:42 am

#70 -  Renewable Energy > Technical Discussion: Other > Re: System requirements
That machine is probably already ground fault protected. Check your owners manual or the electrical schematic for an internal GFCI.

A 20amp draw at 115V would be about 200 amps on the 12V side.  I would start thinking 24 or 48 VDC.

This is not going to be 1-2 batteries and a single panel.  You are most likely looking at somewhere between 6-12 KWH a day. Just ball parking the lower number you are looking at maybe 1400lbs worth of batteries and something above 1.5kw worth of panels.
You are probably looking at a $15K starting price and it could easily double that.

Posted by Ken Hall on Apr 19, 2009 04:55 pm

#71 -  Renewable Energy > Wanted > Re: High School Needs Help - Solar Dog House Project
Since the dog house might be construed as an “occupied dwelling”, does NEC come into play ?.

Posted by Ken Hall on Apr 12, 2009 05:58 pm

#72 -  Renewable Energy > Technical Discussion: Other > Re: Seasonal pv/solar pool heating
Thomas’ calculations are correct as far as raw heat gain. I came up with about 0.42 degrees F per day or 23.7 days for a 10 degree heat gain, based upon 3 panels and ZERO losses.
However, we cannot ignore the losses. So these numbers are pretty meaningless.

Here in Northern California, most people use their pools between  3-6 months a year and we find that a typical installation runs between 50-70 percent of the pool area. (the spread in those numbers really depends on the number of months and/or exactly where in N. Calif. it is. We have a bunch of micro climates)

Assuming that your pool is about 15x30 or about 450 sq. ft and in ground, those numbers would indicate that you could need somewhere in the range of 7-10 panels to provide supplemental heat. This assumes a desired water temp of 80 degrees F. 
(For Florida, where many people are trying to use their pools year round, I understand the recommendation is about 100 percent of the pool area.)

As far as a pool cover, most of the numbers are calculated based upon the use of a cover when night time temps drop more than 15 degrees F below your desired water temperature.  So, if the desired temp is 80, it is a pool cover when the nighttime low falls below 65 degrees F.  OR, you need to increase the heat input.

Doing another back of the envelope type calculation, I came up with about 14 panels to achieve and hold an 10 degree heat rise (to an 80 degree temperature) w/o a cover.  So, would you want to buy an extra 4-7 panels to avoid using a cover ? Maybe discussing a motorized cover (or other easy cover/uncover method) might help.

But, so far, our calculations are based on a lot of assumptions.  You need to be more specific about your needs, either here, or with a professional in your area (best choice).  What is the surface area of your pool, is it in ground or above ground, what is the typical water temp, how much heat gain are you actually looking for, during what months etc. What is the horsepower and gpm of your current pool pump and how many hours a day are you currently running it ?

I don’t want to sound all doom and gloom.  I have run into situations where with a large enough pool pump being run enough hours, installing couple of valves and  a few hundred feet of 1.5 or 2 inch black plastic pipe, provided enough heat gain to satisfy the wants and needs of the owner.  Some people are not after an 80 degree pool, they just want something to take the edge off.

Posted by Ken Hall on Apr 7, 2009 12:32 pm

#73 -  Renewable Energy > RE General Discussion > Re: Airbird Wind Turbines
David is correct about spinning the alternator up to see what it might do.  The guys at my local NAPA store have been quite good to me, spinning alternators on their test bench. You can also use a good varible speed drill press or lathe for the same purpose.

However, I am a little more pessimistic about the outcome. While I haven't physically run into an airbird yet, I have dealt with similar "rip off" designs in the past. My experiance has been that alternator quality is as bad (or worse) as the rest of the machine. Power production at much higher rpms than claimed, not meeting claimed output, poor windings, etc. In the worst cases, no usable output.

If someone is really doing a "rip off", why would they even consider putting a decent, usable alternator into a POS ?

However, if you do spin it up, I would be interested in hearing the results, good or bad.


Posted by Ken Hall on Apr 4, 2009 02:52 am

#74 -  Renewable Energy > RE General Discussion > Re: NEC 2008 code manual

The code is the same regardless of the cover.  But the hardbound edition has explanation articles of the new sections, diagrams and photos that help clarify it. It is about twice as thick as the soft cover.

The spiral bound edition seemed to work best for me. You can fold it over on itself. The pages don't turn by themselves when you let go of it. Easier to carry into the field, etc. But that was when I was working out of it.  The Hardcover might be best for your class, studying, or a desk only reference.

You can get the hardcover new for $110 at Amazon. They also have some used. The softcover is $75. I didn't see the spiral bound.


Posted by Ken Hall on Apr 3, 2009 09:48 pm

#75 -  Renewable Energy > Technical Discussion: Other > Re: Inverter to Subpanel wiring – hot/hot
They may not say that it is a full voltage scheme. But you can ask that question. Or ask if it is NEC (national electric code) approved.  Half voltage schemes are not NEC approved.  Almost any full sine wave inverter will be full voltage.

Another thing you can ask about or look for in the US is the UL approval. If it is UL458, it is definately a half voltage inverter.

Don't even consider trying to get a 220V half voltage scheme and wire it up.


Posted by Ken Hall on Apr 3, 2009 11:11 am

#76 -  Renewable Energy > Technical Discussion: Other > Re: Verify AH on Flooded Bateries?
Find a load that is equal to 5% of the battery capacity. Attach it to the fully charged battery. The battery should support that load for 20 hours.  In the case of a 12 volt, that means 20 hours without the voltage dropping below 10.5 volts.

Posted by Ken Hall on Apr 3, 2009 10:59 am

#77 -  Renewable Energy > Technical Discussion: Other > Re: Inverter to Subpanel wiring – hot/hot
OK, you have half voltage scheme inverters. They are intended for use as plug in or stand alone devices. They are never to be hardwired into an AC system. The manuals should contain the warning that it never be hard wired.

You need to get a full voltage inverter before trying to hard wire it.

Posted by Ken Hall on Apr 3, 2009 01:35 am

#78 -  Renewable Energy > Technical Discussion: Other > Re: Inverter to Subpanel wiring – hot/hot
The simple answer to your question is NO.

I think you had better tell us the make and model of your inverter and why you think it outputs 60Vac.

Posted by Ken Hall on Mar 30, 2009 12:28 pm

#79 -  Renewable Energy > Technical Discussion: Other > Re: Newbie needs help!
"I did take the Kyocera out of the mix and only have the Evergreen panels wired in now."

Just to cover all bases, I hope that means 4 panels, not 5.
Other than that, it sounds good. Let us know how the system works when you get some sun.  If it is still not charging, give us an update with the new voltage readings.

Posted by Ken Hall on Mar 29, 2009 12:27 pm

#80 -  Renewable Energy > Technical Discussion: Other > Re: Newbie needs help!
If you have the controller properly wired and configured as a charge controller, the low voltage disconnect does not function.  That only occurs when it is in load control mode.

The first recommendation is to disconnect the pair of panels that contains the Kyocera 130W. Get the system working with the 4 Evergreens. Then you could attempt to add the mixed pair back in to see how much it drags the array down.  Personally, I would purchase another Evergreen 210W and get rid of the Kyocera (or just stick with the 4 panels). Miss-matched panels in the same array cause problems.

For additional help, we need more info on your system.  Describe where and how the controller is wired. Where are the loads wired to ?  What are the jumper settings ?  What did you set the potentiometers too ?  When it is supposed to be charging, what is the LED doing ?  The more info you provide, the more likely someone is to spot the glitch.

Posted by Ken Hall on Mar 22, 2009 12:17 pm

#81 -  Renewable Energy > Technical Discussion: Other > Re: economic solar water pump design
I agree with Thomas, people power is doable. One of the most ingenious ways is the play pump.


Posted by Ken Hall on Mar 11, 2009 03:46 pm

#82 -  Renewable Energy > Technical Discussion: Other > Re: can high powered DC blowers powered by solar?
Blowers are specified by their output, not the intake. You need to know both the cubic meters per minute (or hour) and the pressure, particularly if you are pushing this thru some sort of AC condenser.

I think you need to spell out what you are trying to do.  How much water are you attempting to produce, what is the typical humidity in percent, what is your budget, etc.

I have been down this path before.  If you are just trying to produce water, there are many less expensive ways to do it.  Even in extremely high humidity areas, you really need to have someone willing to pay for the AC to justify most of the cost. Justifying the cost of solar powered water condensing by itself, is extremely difficult.

Posted by Ken Hall on Mar 10, 2009 01:24 pm

#83 -  Renewable Energy > Technical Discussion: Other > Re: can high powered DC blowers powered by solar?
When you say, "directly generated using the solar panel", are you thinking of panels directly wired to the blower with no batteries ?  Or, is it with batteries ?

As far as the air blower, you did not give enough info for a direct response.  Depending what pressure you want that 1500 cmh to be at, will dramatically change the hp and electrical draw. At lower pressure (300mm H20) you can hit that figure with about 3 hp. At 1,000 mm H2O, you would need about 10hp.

I would suggest that you look at AC blowers that meet your application needs.  Then contact the manufacturer about substituting a DC motor for the AC motor. Once you have a better idea of the HP and electrical draw, it will make the AC or DC answer more evident.

This will of course, impact your other question about how much inverter you need, and possibly the size of the entire system.

Posted by Ken Hall on Feb 11, 2009 01:51 pm

#84 -  Renewable Energy > Technical Discussion: Other > Re: Required Solar Power Agricultural Water Pump

I think your pumping problem is orders of magnitude greater than what is normally handled on this forum. You need to better identify what you have and then seek professional help.

I suspect that your current pumps are 415V, 50 hertz. They most likely have a combined output somewhere near 500 gpm from the 300-400 foot range, although this would be reduced if the local voltage sags, or if they are wired to a single phase.
Pumping 20 hours a day, you are looking at something in the 500,000-600,000 gallons a day range. (roughly 1900-2300 cubic meters a day).

In addition to better defining your current system, you need to define what it is you expect to achieve with the new system.  Let the professionals develop a solution for you, rather than guessing at what might solve your problem.

If you tell them you want solar, that is what they will do. If you leave all options open, they could come up with recommendations from rain water catchment to switching over to dry land rice.

Posted by Ken Hall on Feb 11, 2009 12:21 pm

#85 -  Renewable Energy > Technical Discussion: Other > Re: connecting turbine to solar

This is a device that will step up 12vdc to 24vdc.
However, I do not know anyone that has successfully used one to do what you are proposing. 
First, it will cost you at least 5% of your generation.  Next, there is the potential of logic conflicts between this device and the regulation scheme of the Air X.  This would at minimum increase the losses. It could also shorten the life of the converter.
Last, look at the price.

Sell your Air-X and buy a 24vdc turbine.


Posted by Ken Hall on Feb 9, 2009 12:30 pm

#86 -  Renewable Energy > RE General Discussion > Re: Chinese Solar panels
Are you buying these things through a reputable, established dealer here in the US, or ordering direct from China ? If you are dealing directly, you may have difficulties if any technical or warrantee issues arise.

I haven't used large panels from China. But speaking from experience with other Chinese products, their quality control is sporadic. (Most developing nations have the same problem).

I think you will have less headaches if you stick with the better name brands. Decide which one(s) you want, and buy from a reputable dealer.  The cheapest price is not always the best price.  I want someone that will stand behind the products they sell, and help should any problems arise.

Posted by Ken Hall on Feb 8, 2009 11:00 am

#87 -  Renewable Energy > RE General Discussion > Re: off to on grid

You need to learn about MPPT controllers.
That is how you can make use of the larger/higher voltage panels on a 12vdc system.



Posted by Ken Hall on Feb 4, 2009 03:10 pm

#88 -  Renewable Energy > RE General Discussion > Re: off to on grid

I agree with most of what you said. The one item that could use clarification is "then i see no reason to bother with setting up a small off grid system first."  That holds true for people in net metering states or utility areas with easy interconnect requirements.

But for people that do not, some of the utility requirements are onerous, and it takes a certain size system to justify the tie. If you are getting 5 cents for mid-day generation and paying 10 cents for power at night, do you even want to think about grid tie ?  Or, I remember one utility in the south, where even though they "offer net metering",  they insist on two separate meters and charge you $18 a month (IIRC) to read the second meter.

So, with family budget limitations, building the off grid system over time, and then making a call down stream whether you convert to grid tie or not, makes some sense. Hopefully the rules change during that time and make the decision easier.

For those that live in net metering areas with easy interconnect rules (and good incentive rebates), it is a no brainer. A grid tie inverter and a single panel will do it.


Posted by Ken Hall on Feb 3, 2009 04:42 pm

#89 -  Renewable Energy > Technical Discussion: Other > Re: solar/wind on Xantrex C35 and no charge from wind at night.
You are right about the C-35 controller not dealing with the combined generation. No controller will in PV mode. 

Quote from the C-series user manual. Page 4.  
“Important: The C-Series controller cannot operate in more
than one function at the same time. If several functions are required in a system, a dedicated controller must be used for each function.”

If you refer to your Turbine manual (For the Air X 403 manual, it is figure 4 on page 16.), it will show you how to wire the panels thru the c35 and hook up the air X.
Hopefully your present configuration conforms to figure 4.    

Posted by Ken Hall on Jan 31, 2009 02:02 am

#90 -  Renewable Energy > Technical Discussion: Other > Re: Permanent Magnet DC Motor wiring question

You probably didn't run the battery down far enough.  You have a much bigger battery than I expected.

But the bottom line here is that you really should not be trying to use a solar charge controller on a generator.  A solar charge controller is made for a passive source like PV, not an active source such as a wind (or pedal powered) generator.

I would take it out, and install a blocking diode.
Look for a wind generator blocking diode in the 40-50 amp range.


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