Tristar MPPT Charge controller review - Morningstar TS-MPPT-60 TrackStar

Morningstar's TriStar TS-MPPT-60 Solar Charge Controller is a venerable unit built to a very high standard. In this review, I will detail my experiences with the unit.

The need for a solar charge controller upgrade

I outgrew my 30A PWM controller after adding more solar panels to my array. It necessitated upgrading to a higher capacity charge controller to handle the increased current. The main requirement was it needed to handle at least 60 amps of charging current. This gave me two options:

- Outback FlexMax FM60 MPPT controller
- Morningstar TriStar TS-MPPT-60

As I needed to be able to easily log energy statistics, a controller with computer connectivity was a must. A controller with an RS232 data interface might have been OK, except that my server's Com ports were already used for other datalogging purposes, so another method is needed.

Ethernet would be ideal, as I could simply connect it in to my existing network. The TriStar MPPT-60 has Ethernet as standard. The Outback needs an optional add-on to enable this.

Low self-consumption was also a factor. The TriStar MPPT wins out over the Outback. So the TriStar it was.

Purcahsing it - Australia

As very few local Australian shops sell the TriStar, I looked to the United States to purchase. The TriStar came fitted with the digital meter. The TriStar I received was significantly cheaper than anyone selling them locally, taking into account postage, and the fact that most local sellers do not include the digital meter. A saving of around $200! Express postage was used, and it arrived in approximately four business days.

First Impressions

Having pre-researched the dimensions of the unit to ensure the size would fit a spare spot in my installation, I knew how large it would be. But it was the weight that surprised me. Picking up the Tristar, I could tell by the weight that it was a highly engineered piece of equipment. The oversized heatsink negates the need for a fan. No moving parts is a plus, unlike the Outback controller, which relies on forced air cooling that could be a point of failure.

The oversized cast aluminium heatsink makes it top heavy. A white enamel gloss painted steel enclosure rounds out the rest of the lower body, keeping the connection terminals hidden from view. It has the quality of an expensive whitegood appliance.

Unlike other charge controllers, there are no additional features such as load control and auxiliary outputs. It does only one thing, and it does it well - MPPT battery charging. If you're upgrading from a traditional PWM charger with load control, you may want to keep it to retain features such as Low Voltage Disconnect (LVD). Having said that, without any other features, the TS-MPPT-60 can seem very pricey, but the premium is well worth it due to the exceptionally good build quality and precision engineering.

A comprehensive user manual is included, which explains how to install the unit and set the DIP switches which dictate how the controller operates.

There are two 'processors' in the unit: one for the charge control system and the other to serve web pages (via the built-in Ethernet port). Both firmwares are upgradeable (via the RS232 port), and if the web server crashes, it won't affect the charge control processor - making the TriStar a robust unit. After more than a year, I have not experienced any crashes.

In use

Installed alongside my old SBC-7130, the TS-MPPT-60 was assigned the task of charging batteries in my 12 volt system, with the SBC7130 relegated to load control (mainly as a 30 amp Low Voltage Disconnect) as well as a backup unit should the TriStar fail.

Without re-configuring my 12v nominal solar array, the TS-MPPT-60 already delivered benefits of Maximum Power Point Tracking. Previously, if my battery bank was moderately discharged to 12.3 volts, the PV array would be dragged down to that voltage during bulk charging, with currents approaching the short-circuit rating of the panels. Now, with the TriStar's MPPT, the array voltage is not pulled down, but rather, allowed to sit at its maximum power point value, thereby reducing the solar amperage - thus reducing the resistive losses in my 20-meter long cable to the array. The current boost is especially useful in the morning, when the batteries are discharged from night loads, and the panels are cold (thereby having a higher Vmpp).

Morningstar's proprietary MPPT algorithm is called TrackStar. It performs a fast sweep of the solar array's IV curve about once a minute to find the maximum power point.

The Ethernet interface allows me to read the daily amp-hours without the need to be physically in front of the controller to read the value. This lets me quickly enter the values into my energy log. It also has up to 200 days of logging, unlike the three days on the SBC-7130, so even if I miss a few days, I can always go back through the TriStar's logs to catch up.

Efficiency & Self-consumption

The TriStar is primarily designed for charging large battery banks. On a 12 volt nominal battery system, it has an idle draw of 122mA. Connecting to an Ethernet network bumps the draw to 184mA. If the digital meter is connected (but not Ethernet), the draw is 132mA. When the meter's backlight is activated, the draw increases to 161mA. With both the Ethernet and meter connected, the draw is 191mA (or about 2.4 watts).

This amount of idle (night) self-consumption is barely noticeable on large battery banks, but would be unacceptable for very small systems with only one battery. But for a controller of this size, a small battery bank would be a waste of its capabilities, so in practice, the TriStar MPPT would only be used on large banks where the idle consumption is a negligible factor.

Monitoring

The built-in web server and 'Live View' pages will display the controller's status in near real time. Items displayed include battery voltage, charge amps, ampere hours, PV voltage, PV amps, sweep Vmp. By default, the Tristar MPPT will be accessible from it's NetBIOS name when plugged into a LAN with DHCP available. It can be accessed by entering http://tsmpptXXXXXXXXX (where XXXX is the serial number). Otherwise, if it can't obtain an IP address from a DHCP server, it will automatically assign itself with a 192.168.1.253 address.

The controller also uses an industry standard control and automation protocol called ModBus. Detailed documentation on the parameters are provided, so it is easy to integrate the TriStar MPPT into a third party monitoring system.

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