Hybrid prioities

GeniusAnisakan

I have a 6.5kwh system with one Growatt 2000us battery.  Our grid cuts out for an hour or two most days, night and/or day.  On a sunny day, clearly the panels produce more power than the single battery, but when the grid cuts out, my system cuts off the solar production and reverts to battery.  I would prefer, when the panels produce enough, to use their output first, supplementing if necessary with the battery.  Is this possible?  My main settings choices are grid first, batt first, load first, and my supplier has selected batt first.  (solar comes back on only 5 minutes after the grid is restored).

mcgivor

Welcome to the forum 

What  inverter do you  have, is it an integrated type with an board charge controller? without knowing the make model or a link to the manual, it's impossible to know if it can be configured to do what you want. Only thing I can think of is that the reason for solar disconnect is its part of the  anti island feature to prevent back feeding the grid, for linesman safety 

BB.

Welcome to the forum GeniusAnisakan,

I guess you are somewhere around Myanmar (Burma)?

If you can give us a little more information as to what model of inverter/charger system you have... I have found (I think), the link to the user manuals for Growatt equipment:

https://www.manualslib.com/brand/growatt/inverter.html

Also if you can tell us what kind of battery you have (flooded cell lead acid, AGM, Sealed Lead Acid, GEL, Li Ion LiFePO4, or something else)?

It sound like you have a Hybrid Inverter-charger system? It can both run AC power to your place when utility power has failed. And when the utility power is up--The inverter-charger can also feed "excess" energy back to the grid and reduce your electric bill some too?

And what size of solar array and AH capacity is your battery bank?

In general, for Lead Acid batteries (the most picky type of battery for storing properly charged)--If the battery is >~75% state of charge, it can sit for days/weeks without damage (sulfation). If the battery is under ~75% state of charge, it should be charged relatively soon (within hours or a day) or the battery will begin to sulfate and permanently lose capacity.

In your application, do you know how deeply the battery bank discharges? In a 24 hour period (2 hours down, power comes bank up, and may go down again 12 hour later--as an example) if the battery bank stays above 75% state of charge--Then you can set your charging system to wait until solar panels get sunlight on them (you don't have to recharge from the grid and spend more money).

If, however, the batteries are more deeply discharged (down towards 50% or lower state of charge), then the batteries should be recharged pretty quickly (sulfation can start to happen in hours with a "resting" Lead Acid battery). And at that point, you probably would want utility power to begin to recharge the battery--If it is still dark (or if you have stormy/dark cloudy weather at that time).

You may choose your settings based on the time of year--During the sunny season, you may choose to have your batteries wait until the solar panels can recharge your battery bank. And during monsoon/bad weather times, you may choose to have the grid recharge your battery bank to ensure a longer life tor them.

I don't understand your present options (grid first, batt first, load first) well enough to say which is best.

When you say your solar comes back on 5 minutes after the utility is restored--This sound like Grid Tied (or utility interactive) mode, where the inverter feeds energy back into your utility power (there is a 5 minute delay after utlity power is restored before GT inverter mode will feed power back to the grid). Somewhere along the line, the battery bank needs to get recharged--Which should be (sort of) independent of GT Mode (i.e., the solar panels should charge the battery bank/run your AC inverter off grid whenever there is enough sun available).

-Bill

GeniusAnisakan

Guys, I'm very impressed with your responses.  Quick (very) and to the point.  Thank you.  On details you raise - yes, mid Myanmar.  7 months sunny, 5 months cloudy, but producing 2kv and now rains are ending.  I bought 1 battery since most outages are less than 2 hours or so, and with lockdown it's more than sufficient - Pylontech L-I us2000 - I have its manual.  Growatt PH6000 inverter.  I have its manual.  solar array is 15 panels of 400 watts.  
Myanmar grid does not allow for putting power back into the grid, so export is at 0% in the settings.  Today the log reports voltage outrange (the grid went off).  Upper limit is 260, lower is 160v.
I'm not an electrical nor solar genius, and most of the range of abbreviations are double dutch to me.  so my questions may be a bit simplistic.  The system connects to our house and 12 classrooms in our school (now closed, so a good time to iron out questions).  My main reasons for investing in the system is 1. ethical/environmental, 2. save money, 3. contribute to national power objectives.  The school is currently closed, but when it's open operates only in daytime.  I'd very much like the system to operate as a ups, but appreciate there is always an imperceptible delay when a grid outage occurs.  I'm concerned that the one battery may not be able to handle an extended outage, which is why I'm asking whether it's possible/sensible to get the priority changed around.
server.growatt.com has a demo option.  o grateful for your interest and response.  BTw, my daughter lives in Flagstaff, so I have some connection with your great state!

GeniusAnisakan

mcgivor

The Growatt inverter PH 6000 doesn't come up in any searches could it be a SPH 6000?   https://www.inutec-int.com/us/growatt-1ph-hybrid-inverter-sph6000.html The battery is a rack mounted 2.4 kWh LiFePo4 with 2.2 kWh usable capacity, being such, parrallel connection to increase capacity would  seem logical, don't want to dig any deeper without confirmation we are on the same page regards the inverter.

GeniusAnisakan

You are right.  The capital s on my laptop fails to show!

mcgivor

Will try to find a manual to see what options are available, but I go to sleep early and being an hour ahead of you  in Thailand I'll wait for tomorrow. There is always a solution to a problem, be it conventional or unconventional, need time to digest the information available but not at this moment in time.

GeniusAnisakan

Many thanks

mike95490

A way to have the solar be able to charge the battery with the grid gone, is to use a stand alone Charge Controller.
Depending on how your array is wired for 130VDC or 500VDC determines the cost of the charge controller.

mcgivor

According to the manual grid power is needed to operate this hybrid inverter and the off grid reference is basically a battery backup or UPS,   it's primary  function is grid tied inverter. The manufacturer states that the inverter is not intended as an off grid on a Web page I visited and using it in some way as such is not recommended.

Mike's suggestion of using a high voltage charge controller to supplement the battery during an outage is probably the best solution if the battery nominal voltage is 48V for the model you have,. To achieve such a setup there would need to be a means of transferring the array output to a charge controller  perhaps with a DC auto transfer switch like this https://www.alibaba.com/product-detail/Hot-selling-1000VDC-waterproof-dc-automatic_62328907522.html?spm=a2700.7724857.normalList.1.e26663acQM2yfj&fullFirstScreen=true 

Obviously the charge controller would need to be capable of handling the voltage, there are two 600V offerings from Morningstar and Schneider, but 15 × 400W panels may exceed the maximum voltage threshold, can you post the VOC value of the panels? 

Other factors would be the maximum allowable charging current, this could be increased if nessersary bu increasing the battery capacity. Lots to think about but there's always a solution, the circuitry to achieve a transfer would be relitivly simple but what's needed are the actual numbers.

GeniusAnisakan

Thanks so much for all your research and ideas.  I'm actually not so concerned about charging the battery, as to get the solar panels to keep on working during a grid outage in the day, allowing my school to stay functional.  The inverter shows a fault when grid voltage drops below 160v (the lowest that the settings allow), then after 5 minutes or so the battery gets going.  Why not the solar?  Is this a function of priorities between battery and panels, or just the way its designed?  I suspect (but haven't been able to check) that the panels come on after a further 15 minutes or so.  Of course, Mr Sod has been playing around - far fewer grid outages since I installed solar than before!

mcgivor

My belief is its not intended or designed  to support loads with solar during an outage, the battery may be intended to bridge the gap to allow a standby generator to take over from the grid. My research is limited but some key statements from the manual and website would indicate that this may well be the case. Have you asked the manufacturer the questions you have asked here?, don't assume because it's a Chinese company the don't offer support, some are outstanding in my experience.