Help with APC UPS DIY Hybrid System - Any Ideas?

[Jocko69]

Hi everyone, I have been fortunate to get some items from a data-center that upgraded its systems. I have the following equipment and I am trying to figure out what would be the best configuration to build my quasi-Hybrid system.


4KW Solar Panel setup

APC 10KVA UPS - (SURT10000XLT with Output Transformer for 240V Split Phase output)

Qty. 48 - 12V 100Ah UPS Rated Batteries



Even though its free, it presents some challenges because of the 192V battery requirements. Additionally the system has a built in transfer switch that can automatically switch to utility for power and charging when the batteries run low so it has its benefits. My idea is to use the solar panels to charge the batteries via a MPPT Charge Controller and the system should automatically top off the batteries during the daytime.

I have included a diagram to show the proposed layout of my system.

I do seek some input on how you would recommend that I setup my system. It is very hard to find a mainstream MPPT Solar Charge Controller that charges 192VDC battery banks.


Questions that I have:

(1.) Per my diagram would I be able to split the system with 2 charge controllers and charge them as two 96VDC (or even 4 - 48VDC) banks while they are still hooked up in series to form a 192V bank?

(2.) Without having to invest alot more money (lets say over $1K) any other ideas on how I can setup the system to deal with the 192V battery charging requirements?

(3.) Is having a 192VDC battery back too dangerous? I will have the appropriate fuses/breakers installed on it, but makes me nervous!


I would really appreciate any input on this as I have been racking my brain on how to move forward on this without breaking the bank. I have an electrical background so wiring this up and making modifications to the system is not a problem.

Thanks again for your input, I've been a long time lurker and I'm excited that I am finally able to get my own system going!




Solar Diagram.jpg

[SunEagle]

Wow that system is akin to playing with gasoline and matches.

1. I do not know of any battery chargers that will work on a 96V system or any 48V chargers that will work together for a 96V battery system.
2. It's your money but I really think you are wasting it building that system. It would be better to get one that is a safe Hybrid type that can connect to both a battery system and the grid.
3. Yes a 192 DC volt system is dangerous and should not be built by someone that does not have the expertise to do it safely.

[Mike90250]

There is little safety gear available to the layman, for working with 192VDC battery systems, Arcs are persistent and very dangerous with a high voltage battery, which can dump thousands of amps into a fault.

HV DC Breakers are available but expensive. Code does allow up to a 50VDC battery system, but beyond that, the gear is supposed to be kept locked behind Restricted Access doors

[Ampster]

My only input is that UPS batteries are not designed for deeper charge and discharge cycles. In addition, others with more experience with that chemistry will probably suggest that when in that parallel configuration they will become unbalanced. The unbalance situation could be between the two 96 volt groups and within the two sets of series batteries in each group. There is no method I am aware of that could assure you that each set of solar panels are going to put out the same power everyday.

Yes 192 volts is more dangerous than 48 volts. I think that is one reason you don't find many UL approved systems running voltages higher than 48 volts. I spent some time in the EV conversion community and there are plenty of EV conversions that run at voltages exceeding that. My own VW conversion ran at 116 volts. Others ran as high as 360 volts. It is a matter of respecting that voltage and having safety disconnects, insulated tools, and observing common safety considerations. It is often said that it is the Amps that kill. However it is important to remember that higher voltages can overcome the resistance in our skin and allow enough current to flow through our body to kill us.

[nlvmike]

I'm trying to do the same thing. I'm planning on using the built in charger in the SURT to charge the 192v batteries. I am tinkering with ways to get the solar to run that AC charger. Something along the lines of a grid tie inverter.

[Jocko69]

Just a FYI the SURT charger is very slow so if you have lots of batteries it will be very slow to charge and would require more time to charge the batteries than sun is available.

[SunEagle]

I'm trying to do the same thing. I'm planning on using the built in charger in the SURT to charge the 192v batteries. I am tinkering with ways to get the solar to run that AC charger. Something along the lines of a grid tie inverter.

There isn't any real or legal grid tie inverter that will do that for you.