Using solar panels to charge a long run UPS

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koosbeer

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There are a lot of knowledgeable people on this forum so I thought I would ask this here.

Would it be possible to charge a UPS like this: Crystal Intellipower 4 - 2000va (1200w) UPS w/ 2 x 100Ah
with solar panels in stead of mains?

What type of equipment would be required to do this?

What are the risks and negative effect on the existing equipment (the UPS, the panels, etc)?

If it is not possible, please explain why as well.

I have very limited knowledge about this but feel free to include technical explanation.

Thank you!
 
Thank you for the reply. The solar charge controller was the primary thing I was missing.

Based on the spec sheet of that UPS it stops the UPS from discharging past a certain point so I think that is sorted.

Any idea on the maths on how to figure out how many panels to charge the UPS?
 
You haven't said whether you already have the UPS or not; and if you don't, why are you specifically looking at that one?
 
@YingYang: I do have that specific UPS but I also linked it to provide more information for the smart people to explain the concept of using solar panels to charge something like that. Didnt think it was important to state I have it because Im only looking at the possibility of charging it with solar panels in stead of mains. If I get to the point where implementing this is going to happen I would have asked more specific questions like where and how :) Hope that answers your question.
 
Koosbeer, I'm paying around with this on a smaller scale at the moment.

You'll need this:
http://www.solarsolved.co.za/index....gulators/10a-12v-24v-charge-controller-detail

I'm just working with a small 12V 7Ah Lead Acid Battery and 20W 12V solar panel atm. The Panel has a built in mechanism which prevent discharge when not charging - Thats the sort of panel you want, else you'll need to find a charge controller that does it.

Seems to work at charging the battery up, although I'm not doing regular discharge and recharge. Only getting down to like 75% before charging back up.
 
So in the case of charging the UPS the wattage of the panels dont need to match up with the watt output of the UPS (1200)? So I just need to match the voltage? Sorry, as stated earlier, not very knowledgeable in this area.
 
A UPS is an inverter + charger in one unit.

Depending on what voltage its charging the batteries at, you can assist with panels.

Have a look inside and see if the batteries are in series - in which case you need an MPPT or PWM controller for 24V
If they're in parallel, then its 12V.

From a very cursory check on google, the UPS is running at 24V.


If you connect the MPPT controller to panels and batteries, it should charge them (and stop charging them once they reach a set point)
Hopefully the UPS will stop charging when it see's the voltage of the batteries reaches the correct point, or you'll have issues*


*Fire, exploding batteries or similar.


The wattage of the UPS has nothing to do with the panels. If it has 2 x 12v 100Ah batteries inside, then you have about 1200W of usable power over an hour at 50% Depth of Discharge - any more and you'll damage the batteries.

You could use 1 x 300W panel to support that (and it would take about 4 hours of daylight to recharge the batteries).

Its not really something I'd recommend doing though, as you're asking for issues.

Better off buying appropriate equipment for the job, than jury-rigging stuff, especially if you don't know what you're doing.
 
Last edited:
lsheed_cn said:
You could use 1 x 300W panel to support that (and it would take about 4 hours of daylight to recharge the batteries).
Click to expand...

Just to add if your load shedding is during the daytime you can use the solar panels to run the UPS and keep the batteries mostly full for multiple load shedding in a day. So you can look at adding more panels.
 
Thank you for the replies.

@isheed_cn: what issues would I be asking for? would it damage the panels or the batteries/inverter? This is also assuming that I do have someone in the know to help me implement my jury-rigging :) Also, based on the panel and charge time it would mean that the more panels I have helping the faster it would charge?

@Beachless: that is why I am looking at these options. And as asked above, would adding more panels charge the battery faster?
 
koosbeer said:
Thank you for the replies.

@isheed_cn: what issues would I be asking for? would it damage the panels or the batteries/inverter? This is also assuming that I do have someone in the know to help me implement my jury-rigging :) Also, based on the panel and charge time it would mean that the more panels I have helping the faster it would charge?

@Beachless: that is why I am looking at these options. And as asked above, would adding more panels charge the battery faster?
Click to expand...

Yes it would but you have to stay within the safe charging rate of the batteries.
 
The MPPT controller will dictate size of panel, and how many panels you can add, as that has a voltage and amp rating for input.

eg 24v / 30A means it can output 24v @ 30A. You'll need to dig up what the max voltage and amp *input* is for the controller. Suprisingly this can be hard to find. Most of the cheaper controllers stop at about 50-60v though, so you'd need to run panels in parallel if you wanted more (parallel means voltage stays same, but the amp's go up). Cabling will need to be thicker to cater for that. 1 panel is really sufficient though..

Typically you'd charge Lead Acid batteries at about C/3,
You have (2x) 105Ah battery, so about 30Amps max charge rate into both (60Amps).

Issue is that you have 2 competing things trying to charge the battery - the UPS, and the MPPT controller.
Both will likely work off of voltage when working out the charge curve, but its likely that you might overcharge the batteries (which isn't good).

Suggest read here for a small overview on charging.
http://www.powerstream.com/SLA-fast-charge.htm


Again, I do not recommend what you're trying to do.
 
@Isheed_cn: Thank you again for the quick reply. It would appear, like you said, the problem is overcharging in this case. So what if I completely disconnect the mains and ONLY use the panel(s) to charge the UPS or at the very least have a separate component that can switch the panels charging on and the mains off and visa versa dependant on which one I want to use?
 
I am doing this experiment at moment
2x 100ah bateries
750va long run apc ups
Victron mppt charge controller
300w worth of pannels
Max power I had sofar out of panels was 200w
My ultimate goal will be to disconnect mains to run from solar/bateries
When bat above 27v disconect mains
When bat below 25v reconect mains
Planing to control this with an arduino micro
 
lsheed_cn said:
That would work.
Click to expand...
Think you should start a solar consultancy firm...pretty sure a decent number of people here would pay a pretty penny if you take the headache of sourcing & setting up a solar installation off their hands...
 
@thehunan. Awesome. That is what I was thinking of. Care to share your parts list for the arduino build? Maybe a few pics of what you are doing with the setup?
 
Voltage meusure is a simple voltage divider
Current meusure is a 30amp ac712
Small lcd screen
Im monitoring the pannel amps + voltage
Charge current to battery + voltage
I also monitor curent going in / out of ups
I can see power in/out
And also see power draw to and from ups
 
With the recent events brought proudly by Eskom, what option would members recommend for the solar UPS setup and is it worth it?
 
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