Michel Maupoux's posts

Posted by Michel Maupoux on Jan 22, 2014 03:50 pm

#1 -  Renewable Energy > Technical Discussion: Solar Electric System - Photovoltaic > Re: small off-grid: solar charge controller + inverter compatibility for LVD purpos?
Thanks Tom.  So, do you mean that in this power range there are "online LVD's ", i.e. standalone devices that can be connected inline with an inverter or a load?   The only LVD's I'm aware of so far are built into charge controllers (but only disconnect a directly connected DC load), or built into inverters (but only disconnect when the battery voltage is about 10.7V)
If I could find a standalone (programmable?) device, that would be great.

Posted by Michel Maupoux on Jan 21, 2014 03:28 pm

#2 -  Renewable Energy > Technical Discussion: Solar Electric System - Photovoltaic > Re: small off-grid: solar charge controller + inverter compatibility for LVD purpos?
Hi Tom,
I did mention the siez range: 50-200Wp.  This is not for me, this is for remote systems in developing countries.  We do provide user training & guidelines on not draining the battery too much, but the users are usually illiterate and I'm looking for something more bulletproof than instructions.
Thanks, I do know how to do the calculation, as I have been giving workshops on this for years.  I'm just enquiring about possible improvements in the controller and/or inverter hardware.

Posted by Michel Maupoux on Jan 13, 2014 03:12 pm

#3 -  Renewable Energy > Technical Discussion: Solar Electric System - Photovoltaic > small off-grid: solar charge controller + inverter compatibility for LVD purpos?
Our non-profit helps train about, and install, renewable energy systems in remote villages in developing countries.
Some years ago, I started a topic on this forum, lamenting the fact that small (100-400W) inverters were not compatible with solar charge controllers (e.g. Morningstar or Phocos 12V -10A).  As a result, if an inverter was connected to the DC load side of a controller, it could fry it.  However, LVD protection on such small inverters is often at a very low voltage (e.g. 10.5V) instead of the controller LVD of 11.7V.  So if the inverter is connected directly to the battery, chances are that it will run the battery dead.  Some solutions were offered at the time, involving a relay connected to the DC load output to switch off the inverter.  A simpler approach, but requiring user education and discipline, would be to connect a 1W LED to the DC load, and instruct the user to swithc off the inverter when the LED is off.
However, I noticed that newer solar controllers seem to include new features, e.g. "improved lightning protection", programmable lighting functions, etc.    Does anybody know if  there are either controller-inverter combos, or controllers that would be compatible with inverters, in the 50Wp to 200Wp 12V system range and at reasonable price?

Posted by Michel Maupoux on Jan 14, 2011 01:41 pm

#4 -  Renewable Energy > Technical Discussion: Solar Electric System - Photovoltaic > Re: "24V" PV & 12V battery charge controller?
Hi Dave,

Thanks for all this.  The Morningstar MPPT 15A seems like the way to go.   I don't think we would use the RM, because the users wouldn't be able to make sense of the info.  The built in battery status LED should suffice.
Unfortunately, the panel is part of a larger donation, and it comes with a commitment to report on how it's being used, so I don't think any swap for a 12V is feasible here.

About inverters LVD vs. controller LVD.  Maybe we should start another thread for viewers benefit.  BUt in short, would it be possible to use the controller LVD by installing a relay on the controller load side, and use the relay to switch the inverter input on & off? 
I'm an ME and haven't looked into relays since school a long time ago, but there must be relays that consume current only at the time of activation, right?

[Otherwise, one advantage of the Phocos controller(s) is that they can sound an alarm as well as give a visual signal when LVD is activated.  That would help tell the user something need ot be done]

Any idea why the inverter LVD's are set so low?  Car batteries (the main market for those things) supposedly are even less tolerant of low voltage than deep cycle, so I find this really puzzling.


Posted by Michel Maupoux on Jan 13, 2011 06:46 pm

#5 -  Renewable Energy > Technical Discussion: Solar Electric System - Photovoltaic > Re: "24V" PV & 12V battery charge controller?
Hi David,

Thanks for your help.  The panel is a brand new "blem", and the j-box is sealed, with just 2 cables coming out (I haven't seen it yet, just looked online at a datasheet).  So I'm reluctant to hack at it and remove the epoxy or whatever.
The charge controller you recommended is interesting, but quite different from the products I've worked with so far (I'm quite willing to learn):
- There is no DC load connection, no LVD, no low-charge LED or indication, no state of charge LED or display, just a "charging" LED , and a "Full" LED.
In my experience, as we need to train the users to monitor their battery and not let it discharge too much so that it will last long enough, this lack of informational display is a problem.  The models I prefer allow the user to manage their use to keep the SOC around 75-80%, for a long battery life even without relying on the LVD feature.
Are these designed for systems that will be all in AC, with an LVD in the inverter itself?  For some reason, LVD's on (small) inverters always seem set way too low, like 10.5V, whereas LVDs on Morningstar or Phocos controllers are set around 11.4V.  At 10.5V, the battery is dead, not just discharged.  That's a whole bag of worms I'd love to understand as well some day, but for now I'll focus on just the charge controller.
Other question on the product you recommended (I looked up the user manual): the spec says Max output 10A, regardless of using 12V or 24V.  So if I connect a 215Wp panel, with say, 31Vmp and 7A  at 1kW/m2,  it takes that input but only gives me 10A *12V = 120W Huh That hardly sounds like intended MPPT performance.  What am I missing?
Where we work, i.e. the tropics, we actually get more than 1kW/m2 on good days, so I want to make sure I use all I get.


Posted by Michel Maupoux on Jan 12, 2011 06:02 pm

#6 -  Renewable Energy > Technical Discussion: Solar Electric System - Photovoltaic > "24V" PV & 12V battery charge controller?
We are getting a donation of a 215Wp panel for a small school system in Nicaragua.  That's great, but the Voc is around 40V (Isc ~8A).  I browsed a number of controllers on the site, but it wasn't clear to me what the best (cheap but reliable) choice would be.   Our standard approach would be to have one 12V battery, 12V DC for lights, and an AC inverter for TV/DVD or computer/monitor, and in the past we've used Phocos or Morningstar 10 or 20A controllers, but those require the same voltage on PV side and batt/system side. I saw on this site that the Xantrex C35 can be configured for system voltage of 12 or 24V and accepts input voltage up to 55V.  Is 55V an admissible peak only, or would it work continuously with 40V?  An alternative woould be to have tww smaller batteries in series, keep all sides at "24V", and run everything in AC from a 24VDC to 110VAC inverter.  But again all small inverters I've seen are 12V to 110VAC (or 220).
Should be fairly simple, but I wouldn't want the extra cost of the system to cancel the value of the free panel.
Thanks for any insight.

Posted by Michel Maupoux on Dec 1, 2010 07:19 pm

#7 -  Renewable Energy > For Sale > Re: Whisper 175, tower kit, Trace inverter
hi Greg,

If your system is still available, I might get approval from my boss to purchase it.  We are Green Empowerment, a non-profit based in portland, OR, and are planning some test systems in Nicaragua and Peru for village use.  I do need to check for approval first, though, as we were supposed to do a thorough analysis of various technical options including locally-built.  A great price opportunity might change the process.
Could you e-mail me your original invoice to help me make the case?
I don't know alt-e policy on exchanging e-mail on the forum, but my address is on our web site greenempowerment.org


Posted by Michel Maupoux on Oct 22, 2008 07:19 pm

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

You state that current equipment uses 25HP motors.  Those are very large systems, probably unfit for solar.
To  get an accurate idea of your requirements, you need to say how much water you need per day, and also if the water needs to be lifted further up from ground level.

With a 300-400ft lift (approx 120m), the highest commercially available flow rate I'm aware of with a solar pump would be 3,000 to 5,000 gallons per day (12 to 20m3), with around 2kWp or more of solar panels.

WHich country and latitude/location are you in?  You have very large seasonal temperatures.  Solar pump manufacturers have distributors in many countries but not all.

If you are really talking about 25HP systems and 6 inch distribution pipes, the only approach I would be aware of, would be to build a large solar PV plant with large battery bank and inverter, and using standard industrial AC pumps.

If you have access to the electrical grid and want a hybrid PV+grid system, there is a company in California which has built city systems like that up to 1MW.   I forget their name, but a google search would find them.   Such systems are extremely expensive and require dedicated maintenance.


Posted by Michel Maupoux on Oct 22, 2008 07:03 pm

#9 -  Renewable Energy > Technical Discussion: Other > strong lightning protection for solar pumping systems- expert advice desired
We have been involved for several years with solar water pumping systems used in developing countries to bring water to villages in remote off-grid areas.  I've directly installed 3 systems in Nicaragua and 1 in the Philippines.  In a few weeks, I will be helping a local Filipino non-profit repair 2 systems that they installed a few years ago.

Brands so far include: Sunpumps (AZ), Grundfos, Mono (Australia), and the 2 for repairs are Lorentz.  ALMOST ALL OF THEM SO FAR have had electronics damage apparently due to lightning, even though most of the systems include lightning arrestors, either wired into a main breaker (Sunpumps), or built into the controller (Mono).

A system down means that the villagers (usually women and kids) have to spend several hours every day fetching water down the mountain for their basic domestic needs.

I read in a detailed technical note pulled from this Alt-E site (SAND 2005-0342 Printed February 2005), a recommendation to use two separate ground rods: one as a direct path to ground from the array metallic structure (post, frame, and panel frames ground lugs), and another rod to connect the equipment ground (controller, motor).  A DC lightning arrestor would then be connected at the breaker, connected to +, -, and equipment ground.

Does anybody have any experience with this?

All the manufacturer's installation manuals I've seen show a single grounding rod, and usually the metal case of the controller is attached to the array post anyway, so I suspect that technically their ground terminal is somewhat bonded to the casing and the post and array ground.

Would it make sense to install the breaker and controller to some unique support/post unrelated to the array? Then to use the 2-rod approach?

I also plan to inspect ground lugs and electrical connections between the frames and the existing grounding rods.

Can anybody think of anything else I should be looking for and implementing from now on?

Thanks a lot.

Posted by Michel Maupoux on Aug 30, 2007 02:37 pm

#10 -  Renewable Energy > RE General Discussion > Re: Renewable sector jobs
Hi Grant,
I'm from Europe too, and now live in the Pacific NorthWest (Oregon/Washington).  I find that in general, people in the US are much more mobile than in Europe.  Some people will go to the end of the world to get their dream job.  Some people move to an area they like, and then look for jobs, instead of the other way around.   People from the East coast and South are in general less mobile than those from the West.  And then, there is the matter of finding a job for a spouse/partner, so size of town will be a criteria.
So like with any other marketing topic, you'll find anything, it's a matter of how many % will prefer one way or another.   Try to make both criteria easily viewable/searchable.
Sorry if I muddled the issue further.

Posted by Michel Maupoux on Jun 20, 2007 02:42 pm

#11 -  Renewable Energy > Technical Discussion: Other > Re: Polarity of flourescent cfl bulbs
Yes, when you run your wires to the sockets for your CFL bulbs, you need to keep track of which wire is + and which is -
I believe that the + is the center contact, but my memory may be bad.  Test first, there is no risk.  The CFL will simply not light up if your connection is reverse polarity.


Posted by Michel Maupoux on Mar 28, 2007 07:12 pm

#12 -  Renewable Energy > RE General Discussion > Re: Solar panels for rent
FYI. Here is another small company with an 'invest in solar and lease the equipment' scheme:
Their site says they invest in commercial production site, not individual solar homes.  No franchises. They benefit from Oregon's RE tax credit laws.  And (some of?) the profit is used to fund non-profit RE projects in the developing world.
No idea how big or how successful they are.
They state that 'the principals have designed and installed ~ 3MW of solar in the US" but I think it's a total of what they have done in their (previous) careers.

Posted by Michel Maupoux on Mar 28, 2007 05:02 pm

#13 -  AltE > Discussion > Re: Battery bank or voltage converter?
Re. your converter, keep in mind that converters usually have a narrow good efficiency range.  If you use a 1.5kW inverter for a 200W device, it may work at 80% efficiency or less, i.e. it will draw 250W or more, i.e. draw 20A+ on your 12V battery bank.   Make sure your batteries and wiring can take it.
Good luck with your project.

Posted by Michel Maupoux on Mar 23, 2007 06:02 pm

#14 -  Renewable Energy > RE General Discussion > Re: how-to book for renewables
The SEI book is indeed the standard.
It's always better to have a bit more info than you think you need.  Later, you can go back and it will all make sense.
I found typos and errors in some of the examples in an old copy, but hopefully that's fixed in current version.

If you want a simpler, down to earth PV training manual for small off-grid systems, developed for developing countries aspiring technicians, I recommend you go to the bget.org web site (in Thailand, but broadband is fine), click on "downloads" and download the PV system training manual - a 3.2Mb pdf.   However, it will not include any information on grid-tied systems or on US NEC standards.  This manual was developped by Green Empowerment (US), Palang Thai (Thailand) and others, and is one of the incarnations of what Green Empowerment has been using in village projects for several years in multiple countries.


Posted by Michel Maupoux on Mar 23, 2007 05:44 pm

#15 -  Renewable Energy > Technical Discussion: Other > Re: Phocos charge controller with USB datalogger
Hello James,

Thanks to you and James Polcyn.  I did receive a reply from a support person in Germany, within 48 hours of my initial message.  I used the only e-mail address provided in the software users documentation.

I just now replied to Phocos with the details of all my latest attempts with the datalogger, and this time copied info-usa.  Whoever wants to follow up is fine.  Hopefully  we'll get this solved and will be able to recommend this equipment for future projects.

By the way, the Peruvian ministry of energy, who bought more than 4,000 similar charge controllers for isolated solar home systems scheduled to be installed as we speak, obtained from the vendor a custom version with the datalogger built-in. I believe this is with Phocos.  Any info if this custom version might be made into a standard product and made available to the general public?

Posted by Michel Maupoux on Mar 23, 2007 01:18 pm

#16 -  Renewable Energy > Technical Discussion: Other > Re: Flaky Phocos charge controller and USB datalogger?
Hi James,

Thanks for following up.
Yes, Both the SS and SHS have numbers on the connections.  And the Phocos also provides a connection order.
Here is what the SS manual says (sorry I didn't manage to paste in a snapshot):
"the label has each system connection numbered from 1 to 6.  This is the recommended order of system connections.  However, a different order will not damage the controller"
And later in the operation section:
"If the battery is disconnected during the daytime, the PV array will continue to provide power to the controller.  The SunSaver will immediately go into PWM and provide power at a constant voltage to the load.  This may continue as long as power is available from the PV array".

Maybe I've installed too many SS-10's and generalized this to other controllers.   The SHS installation manual, which is much skimpier, also uses the terms "recommended order of connection", without coments on what happens if it's not followed, and doesn't comment on disconnecting the battery during PV operation.

My intention is not to be on the defensive here, but simply to educate - both the readers of this forum and the manufacturers; and to minimize problems for remote users who don't have access to vendors.  I spent more than 10 years in various functions within service & support engineering departments at HP, for consumer products.  I also trained engineers and call center personnel.  I reviewed a lot of user manuals, and lived with warranty bills for product damage due to poor user instructions.
Believe me, if a product manual doesn't have a clear warning (including some clear symbol) that some action may damage the product, that action will happen.  People who don't read instructions can't be helped much, but at least when an outsider (installer, NGO, volunteer, etc.) installs a PV system on a hut or in a village school, some training is (or should be) generally provided, and user instructions are left behind.  If the product manual doesn't give any warning, no warning will be given to the user, and anything can happen.  There are too many failed PV systems out there in the 3d world, which unfortunately give renewable energies a bad name.  So everything any one of us can do to make the equipment more "bullet-proof" is helping to foster the cause. 
Enough for my soap box Smiley

Thanks for your help, and maybe we'll help save the planet.


Posted by Michel Maupoux on Mar 22, 2007 02:18 pm

#17 -  Renewable Energy > Technical Discussion: Other > Re: Flaky Phocos charge controller and USB datalogger?
Forgot to say that indeed I disconnected mine during daylight, but with our wonderful Pacific Northwest winter, it was rainy or overcast, and not much juice present, so hopefully my controller is OK from that standpoint.

Posted by Michel Maupoux on Mar 22, 2007 02:16 pm

#18 -  Renewable Energy > Technical Discussion: Other > Re: Flaky Phocos charge controller and USB datalogger?
Thanks James for this precious insight.
In the past, I've mostly seen Morningstar and don't recall this being an issue.  Also, I didn't see any warning against that in the Phocos instructions, or in the Morningstar (either SHS or SS models).
It's particularly interesting because I have seen (myself or in pictures) a lot of so-called "solar home systems (SHS) in Latin America and Thailand; they usually do not have circuit breakers (or screwdrivers laying around to disconnect the controller), and you can be sure that people do take batteries away on a regular basis.  Not just every few years when they need replacement, but for example to bring to parties and power sound systems.  I have seen and heard of old controllers being blown away by reverse polarity (re-)connection, so I always insist on having that as an electronic protection when choosing a controller (not a thermal fuse which remote users can't find replacement for).  And I have seen plenty of disablled old controllers where people didn't know what had happened.  But I don't recall ever seeing a warning posted anywhere for the users that before disconnecting the battery they need to disconnect the panels.  I will institutionalize it now wherever I work. 
Phocos did respond today saying disconnection needed to happen in reverse order of connection, but without warning against any damage otherwise.  They have so many protections built in, I would have thought that was included.

If you have any clout with vendors, I would recommend you tell them to add it in bold letters in their owner's instructions.

Thanks again - and I am curious about the other points you said you would address later.

Posted by Michel Maupoux on Mar 21, 2007 07:15 pm

#19 -  Renewable Energy > Technical Discussion: Other > Flaky Phocos charge controller and USB datalogger?
Here is a condensed version of a message I sent to the Phocos e-mail - and they haven't replied.  I bought the Phocos system and most of the equipment through altenergy store a couple months ago.
If anybody has any hint to make this work, that would be great.  Maybe I should ask for a warranty replacement, but I'd like to try and solve this to see if I can make it work in the remote locations where I usually work..

Here are technical support questions about a simple off-grid system using the CX10 charge controller, with the CXI and CXCOM datalogging system.
The rest of the system includes one 75Wp 12V nominal panel (20V Voc), a 72 Ah deep cycle battery, and a simple load demonstration panel with 2 12V 50W light bulbs and one 12V (1W) LED that can be independently switched on and off.  The load is usually turned off, so the current should mostly go to charge the battery.

I purchased one of your controllers for testing and for class use.  I also teach classes on PV design and installation in the US, and I would like to be able to show real data collected through your datalogger.  I would also like to equip some of the systems we install with such data logging capability. 
However, the Phocos system I purchased only worked for two days!

The hardware was purchased in the USA recently, and delivered to me mid-February.

1) Software problem
I downloaded the driver and software from your web site on January 24, 2007, and installed it on my Windows XP laptops after receiving the hardware.
Following the instruction documents, there was no problem to make it all work initially.

After two days where data was collected and communicated well to the PC, on the third day I started getting "charge controller not found"

I tried uninstalling and re-installing the drivers, rebooting, etc.  I even used the Windows XP "system restore" capability, because Windows and McAfee had done automatic updates of my system.

The Device Manager shows the port installed on COM4, and the CXCOM software also showed using COM4.
Every time I plug or unplug the CXI on a USB port, I hear the sound telling me that my PC system is detecting a USB device.

I tried unplugging and re-plugging the green connector in the CX10.

At this point, I don't know what else to do to try and make this work.

Can you please help me recover the functionality of the system?

If that helps, I can send you the last data file that I collected.

2) Charge controller usage question
It seems that, if I disconnect the battery wires from the controller without disconnecting the PV side first, it looks like the whole thing freezes in something like the LVD state (even if the battery voltage is well above LVD).  No current flows to the battery or the load.  I then have to disconnect and reconnect the PV side in order to get the battery side and load to function again.  And during that time, the LCD displays flashing pictures that are not documented in the user manual.
All I wanted to do was insert a multimeter on one of the battery wires to validate the current reading in Amperes.

Am I missing something?

Posted by Michel Maupoux on Mar 21, 2007 06:50 pm

#20 -  Renewable Energy > RE General Discussion > Re: solar water pumping in costa rica
I agree with the other comment about splitting the system.  Also lifting water to then let it gravity feed is fine if the houses are all close to the tank, but a waste of energy if they are a ways downhill.

I am currently working on a system with similar TDH (140m) and length of pipe (900m).  BUt the other key element is the flow rate you want.  Would your tanks hold water for 1 day? 1 week?
In our Philippines system, we are trying to pump 14m3 per day at 140m TDH, and finding a solar pump for such characteristics has been hard.
Total system cost (w/o design and management, as we are a non-profit, and w/o civil work labor as it is provided by the community) will be around $32,000, and the PV power will be about 2700Wp.
For overall formulas and design checklist, I recommend you download our solar pumping system design guide from our web site at http://www.greenempowerment.org/publications.htm

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