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How Can You Monitor Your EPEVER Solar Charge Controllers and Amps with a NetGuardian RTU?

By Andrew Erickson

December 1, 2023


I was at the ISE 2023 EXPO in Kansas City a few months back. A client walked up to my trade show booth. He was interested in a BVM (Battery Voltage Monitor) for his solar sites.

I took down his information. I was then able to call him back a short while later to further brush up on his specific wants and needs. He ended up emailing me back:

I am looking for a system that will give our customers the ability to monitor remote solar charging stations that we produce.

My client need a solution for monitoring EPEVER solar charge controllers and one additional DC current load

My client was facing one critical issue:

We are currently using a solar charge controller made by a Chinese company called EPEVER. We have used a few different models but the main one is the 50A tracer AN series.

The charge controller is equipped with Isolated RS-485 with 5VDC/200mA and MODBUS protocol. EPEVER also has a software that can monitor the system. The software will work with the 50A controller but you can't see the DC load information.

With the 50A controller you must run the load directly from the battery bank, so the power to the load doesn't run through the controller and has no way of being monitored.

As you can see from what he has described above, my potential client was already equipped with more than one device from EPEVER. It helped him monitor his solar charge, mainly the 50A tracer AN series.

His main issue is that the system monitoring software that came with the EPEVER solar charge controller had no actual way of tracking direct current (DC) load information (Direct Current or "DC" load is a unidirectional electrical flow to or from a device.).

This is due to the power from that one large circuit not running through the actual controller (because it exceeds the allowable load) - thus not having any real monitoring method, and the need for a Current Transducer.

My client knew what he needed from an RTU (remote monitoring device)

Following my standard practice as I help a new DPS client, I then asked him if he had any specific needs in dealing with his issue. He was looking for a few things:

  1. A method to measure the power (Amps) going from the battery bank to the load.
  2. Knowing the size of the battery bank and watts sent to the batteries - so that he can develop a "battery life remaining" gauge for the batteries
  3. A method to read the remaining time if no generator was connected (ex. "Site has 3.5 hours of power remaining").
  4. Knowing that the solar charge controller had a generator relay built into it, he wanted to monitor the generator status and info (hours ran, fuel level, etc.).

After I got this info, I had a few questions of my own to really understand how I can best serve client:

Did my client want analog sensing? Did we have a physical size constraint?

Did my client want an analog or discrete current monitor? An analog monitor can show you a variety of information about devices of your facility - for example: you can check your environmentals (humidity, temperature, air flow, etc.). How many channels on those monitors did he want?

Were there any size restrictions that he was working with? Because DPS is a company that prides itself on controlling our entire engineering and manufacturing process in-house, we had a capability that similar companies in our industry didn't: We can customize our parts and services based on our clients' needs!

  • Is this something that needs to withstand certain conditions?
  • Will it need to be crammed in a tight space?

Whatever the limits, DPS isn't just a distributor - use us just like your own personal engineering department.

I got on a phone call with my client to iron out all of these questions. I could then lay out a customized plan of action and a price point for the equipment he would need to accomplish the goals above.

DPS gear monitors critical infrastructure like batteries and environmental conditions

I provided my client with further information about what our products are all about at DPS:

With DPS products, you can monitor your critical infrastructure, be aware of environmental conditions, know when batteries need to be replaced, detect water leaks, keep track of generator status and fuel levels, and bring in SNMP or other protocol alarms from wherever you are.

At DPS Telecom, we design, engineer, and manufacture monitoring products that protect your revenue-generating systems. Our products pay for themselves very quickly by cutting costs you've learned to live with.

My potential client was excited by how malleable and project-specific our services and products at DPS were.

Budget constraints are always a factor

Unfortunately, our client explained that his solar control systems cost $1500-$2000. DPS RTUs range from approximately $800 and up.

The client liked our technology, but was understandably concerned about such a large fraction of the proposed solar controller system being allocated to the monitoring device.

It's disheartening to encounter such circumstances where financial constraints hinder the implementation of sustainable solutions, but budgets are always a reality.

DPS equipment is made in the USA with high quality standards

At DPS Telecom, our commitment to "Made in USA" goes beyond just a tagline. It reflects our approach to customization, quality, and service. We design, engineer, and manufacture each piece of equipment in-house with our dedicated team of professionals.

This allows us to tailor our products to meet our clients' exact needs, something off-the-shelf solutions can't match. However, this level of customization requires an investment of time and resources.

We (and our thousands of clients worldwide) believe this investment is justified because it leads to superior performance, increased efficiency, and a better return on investment in the long run.

I offered this client an alternative plan to suit his budget

I always make sure to follow up after our phone call, so I sent him an email:

As we discussed on the call, DPS equipment probably isn't a good fit for your project budget. As promised, I'll provide a technical summary now for you of how you might attack this using off-the-shelf devices from other manufacturers.

First, I described to him how we would have solved the solution with DPS equipment - had budget not been a problem:

A small DPS "RTU" (we call most models "NetGuardians") would be installed at each solar site. This RTU would have at least one analog input, capable of measuring voltage (VDC) or current (mA). This is what a "current transducer", often this type: (NK Technologies split-core transducer model)

The RTU would also have an RS-485 port for local communication with your EPEVER device.

At this point, the RTU would have all the information you need within itself. This could be viewed in the RTU's web interface, used to trigger email/SMS alert messages, or report to a central monitoring server like our T/Mon or any SNMP manager.

Even then, since I knew that he still needed a solution at a smaller budget, I provided him with an alternative, off-the-shelf solution that might fit his budget:

I would investigate any monitoring device with an analog input OR a "smart" current transducer that has an RS-485 port. Either of those would capture the unmonitored current level you're seeking.

You'll then buy 1 or 2 of an "MODBUS RS-485 to IP" device to get those signals onto an IP network. From there, you can send information from ALL sites to a central MODBUS master on the network.

This would allow status viewing, automated alerts, etc. This MODBUS master would likely take the form of any PC/server running open-source or inexpensive commercially available MODBUS-master software.

Remember to focus on monitoring value - not just price

I understand why this client would want this type of inexpensive solution in this case. It's tough to ever have an "insurance" or "protection" product like an RTU approach the cost of what it's protecting.

This can lead you to creating your own in-house solution stacks or importing parts from overseas companies.

Just be sure that you consider how much a problem will actually cost you. Even if a small device like a solar controller would be fairly cheap to replace, what does an outage cost? Can the users of the produced electricity tolerate an extended power outage? Will the solar array itself be damaged?

Often, you find that an interruption in critical services or the loss of expensive infrastructure is a very expensive proposition.

How can you use DPS monitoring equipment for your solar/telecom sites?

Are you looking for similar help and solutions? Maybe you want to take the entire headache of this project out of the equation and let us handle things for you? Just call me now.

Even if I can't find a price point that fits your budget, I will gladly point you in the right direction.

Call me at 1-800-693-0351. You can also email me at sales@dpstele.com

Andrew Erickson

Andrew Erickson

Andrew Erickson is an Application Engineer at DPS Telecom, a manufacturer of semi-custom remote alarm monitoring systems based in Fresno, California. Andrew brings more than 17 years of experience building site monitoring solutions, developing intuitive user interfaces and documentation, and opt...