DC Lighting design

Q&A and troubleshooting
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1

Hi, I have an application for an off-grid DC Lighting application and need some of the experts on the forum’s advice.

We plan to install Industrial LED Strips 48V in an off-grid industrial application and I need some advice.

The total length will be 50 meters, and the consumption of the LED strips is 8W per meter.
Solar panels charge the lithium batteries during the day and LEDs run off the batteries at night.

Total consumption at night will be x 320W/h, with some losses and autonomy I am working on approx. 7.6kWh Battery capacity. to cater for ~20h of operation.

The solar panels will be 7.7kWp to ensure the batteries get charged.

I’m considering using RS450/100 with 14 x 550W JA/Canadian solar panels.
What can I use between the battery and Load to ensure we have clean 48V or will it be sufficient to simply have fuses in between to power the LED strip loads?

2

Depends on what range of supply voltage the LEDs can cope with and the exact batteries you use. Battery voltage could be up in the 56V range for a nominal 48V system.

You probably want to consider some form of low voltage/SoC cut off to prevent over discharge and damage to the batteries.

3

Thank you WhiteCitySolar for the feedback.
I’m getting the full specs on the LEDs to see what their min/max operating voltage is but I do think some kind of a DC-DC regulator will be best with a wider DC input Voltage and a regulated ~48V DC output. I was looking at something like the Orion-Tr 24/12-20 (240 W) but it can not handle the 320W continuous output. Any suggestions on what could be used?

I was thinking of using the RS450/100, with the Cerbo-GX and CAN bus communication between the MPPT, Li-Batteries, and Cerbo-GX so the batteries BMS can communicate with the system and configure the battery parameters via Victron Connect on the MPPT’s to protect the battery.
Sorry, I am used to having the inverter in the equation with ESS and have not done any direct DC load applications. Any suggestions on the above setup or if there is another alternative I’m open to suggestions to find the best solution.

4

@andrewr
You could look at these… https://www.victronenergy.com/upload/documents/Datasheet-Orion-Tr-DC-DC-converters-isolated-100-250-400W-EN-.pdf
There’s a 48/48-8 with a nominal 380W output, but you can parallel more if needed.
They’re not ‘smart’ in any way, so the Cerbo can’t see what they’re doing directly, but the Remote port can be driven by Cerbo relay for time-based operation, low battery V or SOC, etc. I use a 48/12-20 and it’s very stable.

5

Thank you, John. I completely missed the 48/48-8 model.

6

Welcome to the 48V DC club. I am running a DC grid for light over the last 2 years. I use ordinary 40 Watt LED panels, drop the buildt in power supply and replace it by a Meanwell current source. Further the Eltako UC products all work @48V without problem although they are not specified for. This saves line lenght for the DC line. Very important: Always use sufficient Electrolytic capacitors at the end of long DC lines to compensate its inductivity. Otherwhile electronics will be destroyed by heavy energy from voltage spikes.

A brief description of my grid components is here, unfortunately only in German language.

Anyway, your ideas are feasable but as a prerequisite you need to have basic skills on how to calculate the wiring cross section and fuse sizes for proper installation by the law of Ohm

7

Thank you @Janvi