Chris Brown's posts

Posted by Chris Brown on Jun 26, 2009 01:48 pm

#1 -  Renewable Energy > RE General Discussion > Re: Over 7,000 years of practice...
Was it the same divine power that also gave us a universe of increasing entropy?

If we assume, for the sake of discussion, that we are in a suicide, a 'fall' one might say, and most people would just "wait and see" rather then take action then what do the few, outside the norm, who wish to take action do about it. Those concerned would have two courses of action- 1) fight to make corrective changes, or to continue the metaphor- become a surgeon and repair the wounds self inflicted or 2) flee. 
 

Posted by Chris Brown on Jun 2, 2009 02:17 pm

#2 -  Renewable Energy > Rebate Programs and Net Metering regulations > NY Residents and Installers - Please Help Pass This Legislation
Hello NY Residents!

Please help to get these Energy Bills enacted! Please call, email and write your State Senator and Assemblyman and tell them you support these bills.

These bills will help create jobs in New York and lower the cost of generating renewable energy in New York. New York has the potential to be the first State in the US to enact a Statewide Feed in Tariff; a government program proven to be successful in Germany.   

S 5074 and A 7672 Sales Tax Exemption on Commercial Solar purchases

S 4955-A and A 7653-A Task Force to Standardize Building codes for Solar Installations

S 4954-A and A 7611-A Green loans for Solar Installations

S 4993 and A 7557 Commercial Net Metering correction bill

S 2715 and A 0187 Feed In Tariff Bill for Renewable Energy Systems

Thank to Assemblymen S. Englebright, A. Hevesi Jr. and K. Cahill and Senator A. Thompson for Sponsoring the these Energy Bills.

Find your State Assemblyman here:

http://assembly.state.ny.us/mem/

Find your State Senator here:

http://www.nysenate.gov/senators

If you don't live in NY please direct this information to your friends and colleagues that do- creating a successful Feed in Tariff in New York could create a precedent that other States or even the Nation may follow.
 

Posted by Chris Brown on Jan 9, 2009 04:05 pm

#3 -  Renewable Energy > Technical Discussion: Other > Re: Importance of UL listed modules?
You'll want to check with your code inspector, since it's up to that person, but I'll bet ya an ice cream cone that they will want to see a UL stamp. You inspector, as the authority having jurisdiction, will look for "listed" equipment- while there are other agencies then UL who list UL is the best known in the States. I have heard of several installations failing inspection due to unlisted modules being used.

Your utility may not (and should not in my option) allow for grid interconnection without UL certification.

In the event of fire your home owners insurance most likely would not cover any damages resulting from an unlisted product.

I would only use UL listed modules for most projects in the US.
 

Posted by Chris Brown on May 19, 2008 03:17 pm

#4 -  Renewable Energy > RE General Discussion > Large Wind Turbine News
At the Alternative Energy Store we deal mostly with small wind projects, but in the news last week were two stories that caught my eye- both having to do with large wind projects. The first was this story from the Dallas Morning News about a utility company in TX, Mesa Power and there plans to install 4,000 megawatts of wind turbines by 2014:

http://www.dallasnews.com/sharedcontent/dws/dn/latestnews/stories/DN-pickenswind_15bus.ART.State.Edition1.4687df7.html

This looks to be the largest wind electricity generation project going on in the US right now.

Also last week the DOE released a prepublication version of a report to ‘increases wind energy’s contribution to the US Electricity Supply’. You can read the report here:

http://www1.eere.energy.gov/windandhydro/pdfs/41869.pdf

Salon.com writes about the report:
“May 17, 2008 | A stunning new report just issued by the Bush administration finds that for under 2 cents a day per household, Americans could get 300 gigawatts of wind by 2030. That would:
•  Reduce carbon dioxide emissions from electricity generation by 25 percent in 2030.
•  Reduce natural gas use by 11 percent.
•  Reduce cumulative water consumption associated with electricity generation by 4 trillion gallons by 2030.
•  Support roughly 500,000 jobs in the U.S.”

You can read the Salon.com article here:

http://www.salon.com/news/feature/2008/05/17/wind_power/index.html


 
 

Posted by Chris Brown on May 16, 2008 05:14 pm

#5 -  Renewable Energy > Technical Discussion: Other > Re: charge controller question
There are several articles in the Learn section of our website about charge controllers:

http://howto.altenergystore.com/Library-Articles/Solar-Electric-Power-PV-Systems/Solar-Charge-Controllers/c16/

Almost all controllers will prevent over charging of the battery. If you get a unit that has a low voltage disconnect it will prevent over discharging. Once you read over the articles in the how to section you'll be ready to take a look at the wide selection of charge controllers we offer:

http://store.altenergystore.com/Charge-Controllers/c432/

 

Posted by Chris Brown on May 16, 2008 05:01 pm

#6 -  AltE > Discussion > Re: Evergreen Panels listed as 18V not 24V Why?
This is from the Learn section of our site:

http://howto.altenergystore.com/Getting-Started-with-Renewable-Energy/Introduction-to-Solar-Electricity/a89/p4/

"PV modules have three different voltage ratings that it’s handy to understand. The Nominal voltage of a panel could also be called the “conversational voltage.” When we talk about the voltage of the panels and the other components of the system, we’ll most often use the nominal voltage. Nominal voltage actually refers to the voltage of the battery that the module is best suited to charge; this is a leftover term from the days when solar panels were used only to charge batteries. The actual voltage output of the panel changes as lighting and temperature conditions change, so there’s never one specific voltage at which the panel operates. Nominal voltage allows us, at a glance, to make sure the panel is compatible with a given system. The second voltage rating is the maximum power voltage (Vmp). This is the highest voltage the panel can produce while connected to a system and operating at peak efficiency. The third voltage is open circuit voltage (Voc). This is the maximum voltage that the panel can produce when not connected to an electrical circuit or system. Voc can be measured with a meter directly contacting the panel’s terminals or the ends of its built-in cables."

The Morningstar SunSaver MPPT specs are saying that the max Voc it can handle as an input is 75v and the max nominal PV input is 36v. So long as your charging a 24v battery bank you can connect two Evergreen ES panels wired in series into the controller.

When I'm doing voltage drop calculations I use Vmp for voltage.
 

Posted by Chris Brown on Mar 10, 2008 03:32 pm

#7 -  Renewable Energy > Technical Discussion: Other > Re: 24 volt panels to charge 12 volt battries
Hi Steve,

I would agree with James that MPPT is the way to go if your charging a 12v battery with a 24v panel. Here is some more infomation about the different ratings that solar modules have. This info will be in our How To section shortly.

PV modules’ power output is rated in Watts. A Watt is an instantaneous measurement of electrical power. Power is a rate, much like miles-per-hour on your speedometer shows the rate at which your car is traveling. Power is not the same as energy. Electrical energy is expressed in Watt-hours (Wh) and is a quantity. Electrical energy is like the number of gallons of gas in your fuel tank. Your electric utility bill shows the number of kilowatt-hours (kWh, or thousands of Watt-hours) you use per month. So how does the wattage rating of a solar panel affect the amount of energy the panel produces? Simple-- with all else being constant, a higher-wattage solar panel will produce more energy over time than a lower-wattage panel. A 100-Watt module will produce twice as much energy as a 50-Watt module at the same location during the same period of time. It’s worth mentioning also that solar modules’ rated wattage is based on what the modules produce under laboratory-controlled conditions, called Standard Test Conditions (STC). STC allows solar panels to be compared to each other using the same metric. However, because these rated wattages represent ideal laboratory conditions, it is likely that the module will produce less wattage in actual use.

PV modules also have voltage and current ratings. The rated wattage of a panel is equal to its operating voltage multiplied by its operating current: Watts = Voltage x Amps. The amount of energy in Watt-hours that a panel will produce is a product of the wattage of the panel and the number of hours of full-intensity sunlight, or insolation, that it receives. For example, a solar panel that outputs 100 Watts for two hours will produce 200 Watt-hours of energy. The actual number of Watt-hours a panel produces will very likely be less than this theoretical value due to many factors that affect the efficiencies of the system components. There are standard factors used to correct for real-world energy losses, but to the present focus is the basic electrical principles.

Voltage

PV modules have three different voltage ratings that it’s handy to understand. The nominal voltage of a panel could also be called the “conversational voltage.” When we talk about the voltage of the panels and the other components of the system, we’ll most often use the nominal voltage. Nominal voltage actually refers to the voltage of the battery that the module is best suited to charge; the term is a “leftover” from the days when solar panels were used only to charge batteries. The actual voltage output of the panel changes as lighting and temperature conditions change, so there’s never one specific voltage at which the panel operates. Nominal voltage allows us, at a glance, to make sure the panel is compatible with a given system without having to look at the exact voltage. The second voltage rating is the maximum power voltage (Vmp). This is the highest voltage the panel can produce while connected to a system and operating at peak efficiency. The third voltage is open circuit voltage (Voc). This is the maximum voltage that the panel can produce when not connected to an electrical circuit or system. Voc can be measured with a meter directly contacting the panel’s terminals or the ends of its built-in cables.

Current

Panels also have two different current ratings: current at maximum power (Imp) and short circuit current (Isc), both listed in Amps. The maximum power current is similar to Vmp: it’s the maximum current available when the panel is operating at peak efficiency in a circuit. Similar to Voc, the short circuit current is the current measurement your meter would show when in contact with the positive and negative terminals of the panel while not connected to a system or load.

All these electrical characteristics are used to help determine the size of the PV system and components. These specifications can be found on the label on each solar module as well as on manufacturers’ specification sheets.


 

Posted by Chris Brown on Mar 10, 2008 03:23 pm

#8 -  Renewable Energy > RE General Discussion > Re: PLEASE HELP ME , I am in need of education ASAP ! ! !
Hi,

Here are a few articles from our How To section:

http://howto.altenergystore.com/

Help - I'm New! Where to start?
http://howto.altenergystore.com/The-Basics/Help-Im-New-Where-to-start/a64/

Determining the Renewable Energy Source for You
http://howto.altenergystore.com/The-Basics/Determining-the-Renewable-Energy-Source-for-You/a41/

Beginner's Guide to Solar and Wind Generated Electricity
http://howto.altenergystore.com/The-Basics/Beginners-Guide-to-Solar-and-Wind-Generated-Electricity/a19/

Small Wind Electric Systems: A U.S. Consumer's Guide
http://howto.altenergystore.com/The-Basics/Small-Wind-Electric-Systems-A-US-Consumers-Guide/a75/

Small Wind Turbines: Primer
http://howto.altenergystore.com/The-Basics/Small-Wind-Turbines-Primer/a28/

Wind Power: How to Determine if it is Practical for You
http://howto.altenergystore.com/The-Basics/Wind-Power-How-to-Determine-if-it-is-Practical-for-You/a30/

Tips on How to Site a Small Wind Turbine for Your Location
http://howto.altenergystore.com/How-To-Library/Wind-Generators-Wind-Turbines/Tips-on-How-to-Site-a-Small-Wind-Turbine-for-Your-Location/a29/

Rough estimate of your local wind speed
http://howto.altenergystore.com/How-To-Library/Wind-Generators-Wind-Turbines/Wind-Speed-Map/a77/

We also have a few books avilable in our store:
http://store.altenergystore.com/Books-Classes-Webinars/Wind-Energy/c458/


 

Posted by Chris Brown on Mar 10, 2008 12:46 pm

#9 -  Renewable Energy > Technical Discussion: Other > Re: PV conversion
Hi Tim,

I found these two articles informative:

http://en.wikipedia.org/wiki/Photovoltaics

http://en.wikipedia.org/wiki/Solar_cell
 

Posted by Chris Brown on Mar 3, 2008 06:32 pm

#10 -  Renewable Energy > RE General Discussion > Re: Solar Generator
While this is off topic from the OP, there was that movie "Chain Reaction". I don't recall it being very good, but it was SciFi and it did deal with RE (sorta). I think the story was about someone who builds a machine to turn water into energy and then some baddies try and steal/suppress the technology. It seems like in a lot of SciFi they are able to write their way around the whole energy question, be it Tylium Ore or Dilithium Crystals - but not a whole lot that deals with the energy issue directly (unless the energy source happens to be on some planet surrounded by cyclons, ect....
 

Posted by Chris Brown on Feb 25, 2008 11:14 am

#11 -  Renewable Energy > Technical Discussion: Other > Re: Minimum watts to grid tie?
The Micro Grid-Tie packages use a few high voltage PV modules in series to get the inverters to turn on. While the wattage is low for the system (in some cases less then 500w), the voltage is still over 150 Voc. If your wind generators or hydro turbines can generate 24v or 48v DC you could charge a battery bank and then use a battery based grid tie inverter, like the Outback GFX or the Xantrex XW series. You can check out some of our battery based grid tie inverters here:

http://store.altenergystore.com/Inverters/On-Grid-Off-Grid-Capable-Inverters/c561/

 

Posted by Chris Brown on Feb 25, 2008 10:54 am

#12 -  Renewable Energy > Technical Discussion: Other > Re: Inverter for low Vdc
In that thread I posted a link to the Alt-E Designed Grid-Tie Packages.

http://store.altenergystore.com/Kits-and-Package-Deals/On-Grid-Grid-Tied-Systems/Alt-E-Designed-Grid-Tie-Packages/c1087/

After clicking this link you will see we offer four different grid tie packages. Once you click one of the packages you'll see the parts list for each individual kit- Micro 1 and Micro 2 have the SMA Sunnyboy 700U; Micro 3 and Micro 4 include the  Solectria PVI 1800. 

You can view our full line of grid tie inverters here:

http://store.altenergystore.com/Inverters/On-Grid-Grid-Intertie-No-Batteries/c560/

 

Posted by Chris Brown on Feb 18, 2008 08:12 pm

#13 -  Renewable Energy > Technical Discussion: Other > Re: Off Grid 1000w isolated circuit - need advice
Hi Keith,

I would not go with the nominal 18v panel into a 12v battery bank with a PWM controller (like the C35). If you look at the Vmp of the Evergreen 170 you'll see that it's 25.3 compared to the Vmp of a Sharp 170 that has a Vmp of 34.8v. Both of these voltages are much higher then what is needed to charge a 12v battery and you won't be able to make use of the full potential of the panels. 

If you use an MPPT controller, like the Outback MX60 or Xantrex XW or Solar Boost 6024H you'll be able to down convert the voltage to the make the best use of your input voltage.

You could also go with 12v panels wired in parallel in conjunction with a PWM controller.

I gather that your energy requirements are 1200 watt-hours per day and you have four equivalent sun-hours per day. If all things were perfect you would simply take the energy requirements and divide by sun hours to produce your array size (300w), but in the real world there are many things that force us to size the array larger. If we take into account deviation from standard testing conditions, voltage drop, inefficiencies in the charge controller and inverter and a variety of other factors that can cause power loss in the system we'll have to increase our array size anywhere from 25%-50% (depending on how conservative you want to be and how 'mission critical' your load is). This would give us an array size of 375w - 450w. Having a larger array also gives us the ability to recharge the battery bank from 'cloudy day' usage.     

Here is the logic I use to calculate battery bank size- I'll let you do the math out for your system:

1. Identify the total number of watt hours per day you use

2. Identify the number of days back up you need.

3. Multiply watt-hours per day by back up days (step 1 by step 2)

4. Identify you planned depth of discharge. 50% is as low as I ever plan on. If you want to seriously live on the system (and not just use it for backup) I would go with a 25% dod or better. Convert this number into a decimal (.5 for 50% dod, .25 for 25% dod, .8 of 80% dod). Divide this number by the value in step 3.

5. Derate your battery bank for the lowest average temperature the batteries will be exposed too. Multiple a number bellow by the figure in step 4. This is the minimum watt hour capacity of your battery bank.

Temp in F     Factor
80+           1.00
70            1.04
60            1.11
50            1.19
40            1.30
30            1.40
20            1.59

6. Determine your system voltage. Divide the answer to 5 by your voltage. This is the minimum amp hour capacity of each parallel string of batteries (4500 watt hours / 12v = 375 AH)

7. Select a battery that looks close to your amp hour capacity you calculated in 6. If you can’t find a battery that is close to the capacity, look for one that is as close to half the capacity you need, or close to a quarter the capacity you need.

8. Once you find a battery divide your system voltage by the battery voltage. This will give you the number of batteries you need in series.

9. Divide the number of from question 6 by the amp hour of the battery.  Round up the nearest whole number. This is the number of series strings in parallel.

10. Multiply the answer from question 8 to the answer from question 9. This is the number of batteries you need total.

For Example:

1)   I use 6000 watt-hours per day
2)   I want three days back up
3)   (6000 Wh/day) x (3 days) = 18,000 Wh
4)   I plan to discharge the batteries no more the 40%. (18,000 Wh) /( .4) = 45,000 Wh
5)   My batteries will never get bellow 60 degrees. (45,000Wh) x  (1.11) = 49,950 Wh
6)   I am planning a 48v system. 49,950 Wh / 48v = 1040 AH.
7)   The price per watt-hour in the MKL16 looks good, I want to see if it will work for me. It’s 370 AH at 6v
8 )  48v / 6v = 8 batteries in series
9)   1040 AH / 370AH = 2.8… I’ll round up to 3
10)    8 batteries in series x 3 strings in parallel = 24 batteries.

At this point I would look at another battery option to see if it worked better. I’ll start again at step 7:

7) I want to reduce the number of battery interconnections (especially parallel connections) so I find a Surrette battery that is 4v and 1104 AH.
8 ) 48v / 4v = 12 batteries in series
9) 1040 AH / 1104 AH = .94… I’ll round up to 1 (this actually means I have 1 string in series, so no parallel connections at all).
10) 12 batteries in series x 1 string in parallel = 12 batteries.

At this point I would email my AES sales rep and ask for a quote on 24 MK L16’s and one for 12 Surrette 4-KS-21PS (with shipping) to compare prices. I would break down each battery bank into total watt-hour (battery voltage x battery amp-hour capacity x number of batteries) capacity and then find the price per watt-hour of energy storied (total price of batteries delivered / total watt-hour capacity). I would take to my friends (and fellow forum members) about what they think of the brands, compare warranties, and then buy the batteries I felt best about.



I would recommend going with:

3x Kyocera KC125G 125W 12V Solar Panel
1x 15' MC1 Connector #10 AWG Male/Female
4x GROUNDING LUGS WITH SET SCREWS QTY-1
Mounting of some sort- Ground/roof/pole
1x XW Solar Charge Controller MPPT 865-1030
1x 63 Amp Din Rail Mount Breaker
1x 12 Amp 150VDC Din Rail Mount Breaker
1x MNBabyBox 4 Slot AC or DC Breaker Panel
An appropriately sized battery bank. I have not done the math out, but I'm guessing it will come out to be close to:
2x 8A4D AGM 200 Ah (20 Hr) AGM Battery
1x BATTERY INTERCONNECT CABLE 4/0 13" BLK
1x BATTERY INTERCONNECT CABLE 4/0 13" RED

I would wire the three panels together in series and then into the MPPT XW controller that will charge your two 12v batteries (wired in parallel) at the best voltage and current. This unit also have a built in ground fault protection.

This list comes out to $2,849 and if installed this year you could use it to take advantage of the federal tax credit for 2008. (www.dsireusa.org for more info on the tax credit)

 

Posted by Chris Brown on Feb 8, 2008 05:59 pm

#14 -  Renewable Energy > Technical Discussion: Other > Re: Minimum watts to grid tie?
Hi Paul,

Check out some of our micro grid tie systems:

http://store.altenergystore.com/Kits-and-Package-Deals/On-Grid-Grid-Tied-Systems/Alt-E-Designed-Grid-Tie-Packages/c1087/

We were able to design a system that's as small as 240w! I think that System's 3 and 4 are the best in this category. They are very expandable systems- you can have up to 10 of the Sanyo 195w panels in the system without needing to upgrade the inverter.

If you need a custom quote on a grid tie system let me know.

-Chris
 

Posted by Chris Brown on Jan 9, 2008 02:10 pm

#15 -  Renewable Energy > Technical Discussion: Other > Re: Crystalline or Amorphous
Hello Charnon,

Most grid tie PV installations use crystalline panels, like the Evergreen or Kyocera panels. Sometimes people will use a Sanyo panel that incorporates both crystalline and amorphous cells in the same module.

In general check out the 150+ watt panels- these are the units that are used for grid tie systems most of the time:

http://store.altenergystore.com/Solar-Panels/150-Watts-Up-Solar-Panels/c741/

 

Posted by Chris Brown on Jan 2, 2008 05:33 pm

#16 -  Renewable Energy > Rebate Programs and Net Metering regulations > 2007 Freeing the Grid Report
Here is a excellent report on net metering and interconnection from the Network for New Energy Choices. This should be a mandatory read for anyone thinking of putting up a grid-tied or grid connected system: 

http://www.newenergychoices.org/uploads/FreeingTheGrid2007_report.pdf

 

Posted by Chris Brown on Dec 16, 2007 01:56 am

#17 -  Renewable Energy > Rebate Programs and Net Metering regulations > Re: News Articles and Websites
Tom, I agree completely! PV is sexy and it's the first thing people think of when they think RE but it's a whole energy consumption/production issue that needs to be addressed. That's exactly why I edited the post to include a link to the Green Communities Act. We need legislation that focus on efficiency and generation. I think the Green Communities Act is a good model for the Commonwealth and the nation for this reason.

 

Posted by Chris Brown on Dec 14, 2007 12:31 pm

#18 -  Renewable Energy > Rebate Programs and Net Metering regulations > Massachusetts incentives for buying solar panels
State to launch $68m solar panel program

http://www.boston.com/news/local/massachusetts/articles/2007/12/14/state_to_launch_68m_solar_panel_program/

Good to see some more programs in my home state of MA!

Also if your in MA check out The Green Communities Act of 2007 and if you support it, write your representative and let them know.

www.mass.gov/legis/house/ht04365_summary.pdf

Find your representative's contact info here:
http://www.mass.gov/legis/memmenuh.htm
 

Posted by Chris Brown on Dec 12, 2007 10:51 pm

#19 -  Renewable Energy > Technical Discussion: Other > Re: Proplyene Glycol Mix Vs RV Anti Freeze
The folks over at AET recommend Sierra antifreeze:

http://www.sierraantifreeze.com/

The folks over at Heliodyne sell their own PG:

http://store.altenergystore.com/Solar-Hot-Water/Accessories-MISC-SYSTEM-COMPONENTS/Heliodyne-Non-Toxic-Propylene-Glycol-2-Gallon/p5942/

Both of these solutions are propylene glycol and both should be mixed with water. I've heard of a few different ratio's of water to PG through around but 50/50 seems to be the most common. According to the MSDS for both products the Sierra antifreeze is 94%-96% PG and Heliodyne Dyn-o-Flow is 94% PG.
 
http://store.altenergystore.com/mmsolar/others/Dyn-O-Flo_HD_MSDS.pdf
http://www.sierraantifreeze.com/images/sierra_msds.pdf

Some car/rv antifreeze solutions are ethylene glycol- which is more toxic the propylene glycol. EG is not for use is a solar thermal applications and if your going to buy antifreeze for domestic hot water heating make sure to use PG and a double wall heat exchanger.
 

Posted by Chris Brown on Nov 20, 2007 01:58 pm

#20 -  Renewable Energy > Technical Discussion: Other > Re: Freetricity.com
PacWind has some cool units. I like the company; they are very friendly people and they have a nice website. Does anyone have any third party testing of these units? If I can find some I'll post it.
 

Posted by Chris Brown on Oct 29, 2007 06:04 pm

#21 -  Renewable Energy > RE General Discussion > Re: Magnum controller
You can check out Magnum Energy's full product line here:

http://www.magnumenergy.com/productsfront.htm

Most likely what you were being quoted was a 'remote control' and not a charge controller (like the MX60). The Magnum remote controls are easy to use and allow you to use a lot of the advanced features of the inverter. I'm not aware of a charge controller made by Magnum, but they did just come out with a new shunt based battery monitor. I don't think they have the spec's online yet, but it will be cool to be able to use the remote control as a full featured battery monitor in the near future.
 

Posted by Chris Brown on Oct 17, 2007 02:01 am

#22 -  Renewable Energy > Technical Discussion: Other > Re: Powering cabin from house system
Holy Smokes... this is like an SAT question.. A train leaves Dallas at 9:45 in route to Sacramento... LOL Cheesy

I would say IF your gonna do it, make sure you go into some batteries before the inverter...

Anyone have any hands on with splitting DC Huh
 

Posted by Chris Brown on Oct 17, 2007 01:46 am

#23 -  Renewable Energy > Technical Discussion: Other > Re: Parallel 2 charge controllers
Hi Paul,

Sorry for more questions! When you say 70 amp max, is that the max output of the solar array? How many panels do you have total? What sort of configuration do you have set up now (how many panels in series and how many series strings in parallel?)

When I size a controller I take the Isc of the array and multiply that number by 1.56. Then I find a charge controller that's larger then the number. You also might want to look into an MPPT controller so that you can go into the controller with a voltage that is higher then your battery bank and allow the controller to step down the voltage (while boosting the current). You could go into a MPPT controller with a nominal 48v and come out with a nominal 24v. Plus you will also get the added bonus of the power point tracking that will give you more energy in your batteries in lower light conditions- not to mention you will have less power loss in your transmission if your at a higher voltage.

If you're going to parallel the controllers you'll want to have the positive battery outputs and negative battery outputs of each of the controllers meet at a bus bar (or on the battery bank terminals I guess).
 

Posted by Chris Brown on Oct 13, 2007 01:59 am

#24 -  Renewable Energy > Technical Discussion: Other > Re: Powering cabin from house system
What is the distance from the hydro turbine to the batteries? Also the distance from the solar array and wind turbine to the batteries? Between the turbine and the batteries, where in the cabin in this line?

The XW power system from Xantrex just came out a few weeks ago. I'm not an expert on the system (I haven't even had a chance to read the manual more the a few pages), but the system looks very cool for handling multiple power inputs in a system like this.

It might be less expensive (and simpler) to run an AC line from your current inverter to the cabin, depending on setup.
 

Posted by Chris Brown on Oct 13, 2007 01:50 am

#25 -  Renewable Energy > Technical Discussion: Other > Re: Parallel 2 charge controllers
Hi Paul,

What kind of panels do you have? Who is the manufacturer and what model? What's the Voc and Isc of panel (hopefully printed on the back of the module)? Where is the array located?

Thanks!
Chris
 

Posted by Chris Brown on Oct 12, 2007 02:42 am

#26 -  Renewable Energy > Technical Discussion: Other > Re: Air-X Bad Experience
Hi John,

Thanks for posting about your experience. I know you have talked to myself, James and the folks at SWWP about your Air-X  for a few weeks now. Let's chat tomorrow and work on figuring out a solution to your problem.

-Chris
 

Posted by Chris Brown on Oct 12, 2007 02:35 am

#27 -  Renewable Energy > Technical Discussion: Other > Re: What do you understand by these terms?
A watt (W) is a instantaneous measurement of power. A kilowatt (kW) is a thousand watts. Electrical power is a rate that signifies the relations of voltage to current. A watt is equal to the voltage multiplied by the current of a system at a given point.

A watt-hour (Wh) is a cumulative mesurement of energy. A kilowatt-hour (kWh) is a thousand watt-hours. If a 1 kW generator runs for 2 hours it produces 2 kilowatt-hours of energy. (kW x hours of operation = kWh.) The kilowatt hour is the unit of measurement that most utility companies use to bill there customers. 

To use an analogy, we can think of electricity like beer. If we think of beer flowing from a keg, the volume of beer would be like the current and the pressure in the line would be like the voltage. If we fill glasses from the tap for an hour, the number of pints would be like kilowatt-hours per hour and our utility bill would be like the tab at the end of the night. If we pump the keg it's like increasing the voltage and if we get a bigger tap it's like increasing the current- either way we're increasing the amount of beer that can be poured- similar to how wattage increases when voltage or current increases. Right now I'm working on a video that demonstrates this analogy- I think it's gonna take at least three kegs to prove my point. Stay tuned. Smiley

The quote you have is a little misleading. It doesn't say if the 550,000 kWh is produced per day, week, month or year. If we ignore all inefficiencies in a system, a 400kW array in the sun for 5 equivalent sun hours a day will produce 2000 kWh per day, 60,000 kWh per month and 720,000 kWh per year. With some reduction to the sun hours and some reductions due to inefficiency in the system, it would make sense that an array that size could produce that amount of electrical energy in a year.

Check out the Photovoltaics: Design & Install Manual. It's a good source of info:

http://store.altenergystore.com/Books-Workshops-Videos/Solar-Electric-and-Passive-Solar/Photovoltaics-Design-Install-Manual/p481/

Wikipedia has good entries on Watts, Energy, Power and other basic electrical definitions.

http://en.wikipedia.org/

 

Posted by Chris Brown on Oct 8, 2007 11:35 pm

#28 -  Renewable Energy > Technical Discussion: Other > Re: What's the implication of # of back up days and temp on battery bank sizing
Hi Vincent,

I think that calculator is acting a bit funny. I know James is working on it.

Here is the logic I use. I’m not sure if the calculator uses the same (or something similar)

1. Identify the total number of watt hours per day you use

2. Identify the number of days back up you need.

3. Multiply watt-hours per day by back up days (step 1 by step 2)

4. Identify you planned depth of discharge. 50% is as low as I ever plan on. If you want to seriously live on the system (and not just use it for backup) I would go with a 25% dod or better. Convert this number into a decimal (.5 for 50% dod, .25 for 25% dod, .8 of 80% dod). Divide this number by the value in step 3.

5. Derate your battery bank for the lowest average temperature the batteries will be exposed too. Multiple a number bellow by the figure in step 4. This is the minimum watt hour capacity of your battery bank.

Temp in F     Factor
80+           1.00
70            1.04
60            1.11
50            1.19
40            1.30
30            1.40
20            1.59

6. Determine your system voltage. Divide the answer to 5 by your voltage. This is the minimum amp hour capacity of each parallel string of batteries (4500 watt hours / 12v = 375 AH)

7. Select a battery that looks close to your amp hour capacity you calculated in 6. If you can’t find a battery that is close to the capacity, look for one that is as close to half the capacity you need, or close to a quarter the capacity you need.

8. Once you find a battery divide your system voltage by the battery voltage. This will give you the number of batteries you need in series.

9. Divide the number of from question 6 by the amp hour of the battery.  Round up the nearest whole number. This is the number of series strings in parallel.

10. Multiply the answer from question 8 to the answer from question 9. This is the number of batteries you need total.

For Example:

1)   I use 6000 watt-hours per day
2)   I want three days back up
3)   (6000 Wh/day) x (3 days) = 18,000 Wh
4)   I plan to discharge the batteries no more the 40%. (18,000 Wh) /( .4) = 45,000 Wh
5)   My batteries will never get bellow 60 degrees. (45,000Wh) x  (1.11) = 49,950 Wh
6)   I am planning a 48v system. 49,950 Wh / 48v = 1040 AH.
7)   The price per watt-hour in the MKL16 looks good, I want to see if it will work for me. It’s 370 AH at 6v
Cool   48v / 6v = 8 batteries in series
9)   1040 AH / 370AH = 2.8… I’ll round up to 3
10)    8 batteries in series x 3 strings in parallel = 24 batteries.

At this point I would look at another battery option to see if it worked better. I’ll start again at step 7:

7) I want to reduce the number of battery interconnections (especially parallel connections) so I find a Surrette battery that is 4v and 1104 AH.
Cool 48v / 4v = 12 batteries in series
9) 1040 AH / 1104 AH = .94… I’ll round up to 1 (this actually means I have 1 string in series, so no parallel connections at all).
10) 12 batteries in series x 1 string in parallel = 12 batteries.

At this point I would email my AES sales rep and ask for a quote on 24 MK L16’s and one for 12 Surrette 4-KS-21PS (with shipping) to compare prices. I would break down each battery bank into total watt-hour (battery voltage x battery amp-hour capacity x number of batteries) capacity and then find the price per watt-hour of energy storied (total price of batteries delivered / total watt-hour capacity). I would take to my friends (and fellow forum members) about what they think of the brands, compare warranties, and then buy the batteries I felt best about.

Almost as much fun as a 1040!
 

Posted by Chris Brown on Sep 24, 2007 07:49 pm

#29 -  AltE > Discussion > Re: Solar panels and New Roof
Hey Julian,

Thanks for the info on the SHR17's. Any thoughts on the Sharp 62w tiles? On a 1 kW installation 16 electrical connections seems a lot more manageable then 55. 

-Chris
 

Posted by Chris Brown on Sep 21, 2007 11:39 am

#30 -  Renewable Energy > Rebate Programs and Net Metering regulations > First Renewable FIT Introduced in U.S.
"Patterned after Germany's highly successful Renewable Energy Sources Act, Veteran Michigan Assemblywoman Kathleen Law submitted a bill to the Michigan House of Representatives earlier this week that creates the first comprehensive renewable energy feed-in tariff (FIT) introduced into any U.S. legislature."

Rooftop solar less than 30 kW: $0.65 USD/kWh


http://www.renewableenergyaccess.com/rea/news/story?id=50004

*edit kW to kWh... thanks james Wink
 

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