Good day folks! My name is Bill Mellema. I represent Morningstar Corporation. I will be monitoring this forum and answering technical questions concerning our charge controllers.

Hi Bill,

It's great that another manufacture believe's in the internet for help !!!. Hopefully this will get other interested in joining the pond

Thanks !

[img]images/smiles/icon_biggrin.gif[/img]

Thank you, Bill from Morningstar!

Just so you don't get bored waiting for a technical question... what's a charge controller?

Why would I need/want one? How to choose a good one (you're allowed to use examples that show yours are good), what to steer clear of, what rough prices one should expect... :-)

Pick and choose as you will from the above. My project will be to provide 450 Kwh per month to my house, using PV, estimated time six months (must learn a lot).

The utility is not friendly to intertie (and I'm afraid they'd catch on if they came to read the meter and it was moving backwards) so I'll probably have to go with batteries even though I have heard they reduce efficiency and cost a lot.

You did say something about wanting questions... <grin>

Rodolfo

Rodolfo,

Charge controllers are wired between your PV array and the battery bank. The controller will allow the battery to fully charge, and then regulate the current from the panels so that the batteries do not overcharge. Typical charging stages are:

bulk - full current charging until batteries are recharged

regulation- the voltage at which the battery is maintained while it comes to a full charge

float- lower voltage that the batteries are held at after a full recharge

equalize- a higher voltage charge administered periodically to equalize cell voltages and the bank and bubble the electrolyte.

Many controllers will also have load control functions. Load control can disconnect your DC loads when the battery discharges too far or may disconnect them if the battery voltage becomes too high (another charging source on your batteries that is over-charging)

Regards,

Bill

Thanks, Bill.

Another crack of light shines into a thick skull. :-)

Seriously, though, if I were to generate between 450 Kwh and 900 Kwh per month using PV, and wanted a battery backup (or to go off-grid completely), what should I look for in a charge controller?

So you don't get accused of advertising, I'll ask directly: which of your products would best fit this application? What are estimated prices I could expect to pay? Any significant pros/cons? Any competitive comparisons to other units?

Thanks!

Rodolfo

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Rodolfo J. Paiz:
Thanks, Bill.

Another crack of light shines into a thick skull. :-)

Seriously, though, if I were to generate between 450 Kwh and 900 Kwh per month using PV, and wanted a battery backup (or to go off-grid completely), what should I look for in a charge controller?

So you don't get accused of advertising, I'll ask directly: which of your products would best fit this application? What are estimated prices I could expect to pay? Any significant pros/cons? Any competitive comparisons to other units?

Thanks!

Rodolfo<HR></BLOCKQUOTE>


Rodolfo,

Your battery charging needs may be met using the battery charging and UPS functions built into many of the inverters on the market today. Our product line covers stand alone PV systems consisting of an array, battery bank, and loads. Stand alone inverters are typical loads in these types of systems. Our controllers are designed to charge and maintain the batteries as well as control DC loads.

If you will require datalogging, metering capabilities, and the like, we will be releasing a 45A and 60A controller with communications capabilities 1st quarter 2003. The TriStar will be capable of charging, load control, or diversion. Pricing will be around $150 for the 45A version. Also expect marketing materials and competitive comparisons to be released when the product is introduced to the market. As always, let me know if you have any questions. [img]images/smiles/icon_smile.gif[/img]

Best Regards,

Bill Mellema
MS Engineering Dept.

After spending a little more time reading, it _seems_ to me almost like one should decide at the outset whether or not batteries will play any part in a system. This decision seems to drive system design into two diverging routes.

I would love to take something like a Sunny Boy 2500U, put the maximum capacity of PV panels on it (whatever that happens to be), and start there as a grid-tied system.

From there, I would later like to add battery backup to my system, sufficient for, say, 12 hours of power outage. Other than natural disasters, I don't foresee power outages ever lasting even half that long...

Finally, I would like to grow the system such that PV supplies 90% of my electrical needs and the grid only the remaining 10%; this keeps the grid available for peaks in usage.

HOWEVER, my reading indicates that this is not viable: that I should choose one inverter if I'll have batteries, and another if I won't, and that guessing wrong will require the purchase of a second inverter later.

Am I missing something?

Thanks,

Rodolfo

Actually, you can combine goals into a single integrated system.

If your primary objective is a grid-tie system, then by all means direct your design to achieve this end. The Sunny Boy inverter is the hands-down champ at this point in time and you can leverage its superior MPPT technology.

If you are concerned about power outages, then add a UPS system. Define your critical loads and carry them on a sub-panel that is fed from and that you can isolate from the service entrance. Isolation can be manual or through an automatic relay. Design your battery bank to provide the load and autonomy you desire. Charge the batteries with an AC to DC charge controller. Provide a second inverter to power your critical loads-- an Exeltech is a good choice. Prosine is decent as well. This inverter does not need all of the bells and whistles (like MPPT and charge control) and will end up being significantly cheaper to purchase.

Voila! You have satisfied both of your goals and have had to make no design compromises. This is probably the best way to go until the Sunny Island or FX-2000 are widely available.

Good luck!

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Solar Mo:
If you are concerned about power outages, then add a UPS system. Define your critical loads and carry them on a sub-panel that is fed from and that you can isolate from the service entrance. Isolation can be manual or through an automatic relay. Design your battery bank to provide the load and autonomy you desire. Charge the batteries with an AC to DC charge controller. Provide a second inverter to power your critical loads-- an Exeltech is a good choice. Prosine is decent as well. This inverter does not need all of the bells and whistles (like MPPT and charge control) and will end up being significantly cheaper to purchase.
<HR></BLOCKQUOTE>

This is exactly what I have done. Prior to getting my grid tie PV system (which is still quite small), I had an emergency generator and a transfer switch. Knowing that most outages would be short term, I purchased a 1500/3000 watt inverter off of Ebay. I then bought a couple of deep cycle batteries and a float charger. I have the inverter normally plugged into the generator's transfer switch. If the grid goes down, I can flip a few switches and run my refrigerator and freezer off of this inverter for up to 24 hours. Total cost was about $300. If the outage is longer than that, I can always fire up the generator. However, short of some major catastrophe, I doubt the grid will be down longer than that. I am contemplating adding a charge controller with some sort of transfer switch for the PV array to charge the batteries during the outage and get a longer run time, but the odds are that would never be needed.

[ November 06, 2002: Message edited by: Mark Lopez ]

That's a lot of work and definitely not an automated process. Most of my customers (and my wife) require systems that are automatic. If you want a battery based system it's hard to find a better unit than the SW series. What's really need is a top notch MPPT charge controller for systems requiring batteries.