Surgeguard and How It Can Benefit You!

In this episode we go over multiple models of surge protection that we at the Inverter Service Center recommend and carry. We talk about different features and prices so that you can get the protection that best suits your application. So if you guys are ready…. Let’s dive on in!

Monitor Your PV System With Web Monitoring Software

web monitoring software

PV system inverters and charge controllers are typically equipped with some sort of control panel and indicators, but it’s often rather rudimentary. The equipment manufacturers may offer an optional interface panel to allow for a wider range of local configuration, control, and performance reporting.

A step up in configuration, control, data logging, and reporting is web monitoring software. By connecting your PV system to the web – either directly via a router or via a PC, hard-wired or via Wi-Fi – you can monitor and even control your system remotely.

Some systems can be configured to send a message when certain conditions exist, such as low battery state of charge or some other fault. This feature allows you to take corrective action before serious damage could occur.

Unfortunately, there’s not yet a standard data set for the PV industry. Accordingly, owners typically must buy proprietary hardware and software from the inverter and controller manufacturers. However, by monitoring, logging, and analyzing system performance, either locally or remotely, you may be able to optimize your specific system’s performance and load scheduling.

Monitoring is a popular option for residential, business, and utility installations. Additionally, detailed local monitoring and control may be useful in your RV or on your boat. Give Inverter Service Center a call at 800-621-1271, and we’ll be happy to discuss the web monitoring software options available for your system.

Battery-Based Charge Controller Technology Explained

Morningstar Solar Charge Controllers

The charge controller in a battery-based PV system has but one main function: to keep the batteries from being over-charged. Most charge controllers can now be configured for battery voltage (12, 24, 48 V nominal), battery type (flooded-cell, AGM, gel), and they offer multi-stage charging algorithms (bulk, absorption, float, equalization), resulting in dependable performance and enhanced battery life.

Some controllers offer temperature compensation (increase target voltages when the batteries are cold and reduce voltages when they’re warm), can be fine-tuned to a particular application, offer voltage-controlled switches, and provide status indicators or displays. At least one controller can now talk to the operator!

PWM vs. MPPT Charge Controllers

One key remaining difference in battery-based charge controller technology and pricing is pulse width modulation (PWM) vs. maximum power point tracking (MPPT) architecture. PWM charge controllers are among the first “smart” controllers, and they may include many of the features mentioned above. These controllers use PWM technology to accurately maintain target voltages for the absorption, float, and equalization stages by varying and limiting charge current.

However, a characteristic of the PWM controller is that the PV module operating voltage is essentially set by the battery charging voltage when the controller is operating in its bulk stage. For example, although a module’s maximum power point voltage might be 17V,  it will operate at 13V if the battery’s instantaneous bulk charging voltage is 13V. The 4V loss means a 24% power reduction under these conditions, which translates into a longer bulk charge period.

An application complication when using a PWM charge controller is that the module- and array specs must be carefully matched to the operational environment and the particular battery target voltages. Module voltages that are too high will not deliver full power, resulting in less than expected system performance.

This can be especially disheartening in the winter when module voltages are typically higher than in summer. And, large low-voltage arrays require (expensive) large gauge wiring to minimize power losses in the wiring home run between the array and the controller.

Charge Controller Breakthrough Technology

MPPT charge controllers are a true technology breakthrough. They effectively operate as smart DC-DC converters and provide many benefits to PV system design and operation. At the most basic level, an MPPT controller can track a module’s optimal voltage and current points independently of the battery voltage to deliver maximum power (maximum voltage x maximum current = maximum power).

Borrowing from the example above, a module operating at 17 V and 4 A in bulk mode via an MPPT controller can deliver 13 V and almost 5A.

By converting “excess” module voltage into additional charge current, the bulk charging state is shortened compared to a PWM unit. This feature is especially valuable during short winter days when a cold module’s even greater “excess” voltage is converted into even more charge current.

High battery-current MPPT charge controllers can be even more sophisticated. For example, these can take arrays in the 18 V to 60 V (nominal) range and convert the “high” array voltage down to a lower voltage battery bank, all while proportionally increasing the available charge current.

This feature allows for much broader and more competitive selection of PV module specifications, all while providing for an optimized PV system which can more easily meet operation expectations. And, by using a “high” voltage array to charge a “low” voltage battery bank, you can reduce your home run cabling costs.

MPPT controllers invariably cost more than PWM models. However, everything else being equal, MPPT controller-based systems require smaller – as less costly – PV arrays. Including reduced balance of system costs, an MPPT controller-based PV system can be quite competitive from a financial perspective.

Give Inverter Service Center a call at 800-621-1271, and we’ll be happy to discuss your system configuration options.

About the Author – Jim Goodnight – also known as “crewzer” — is a retired solar industry application engineer, product manager, and forum moderator and has previously written for Home Power and Solar Professional magazines.

3-Stage Alternator Regulators


Vehicle starting batteries – usually flooded-cell lead-acid – are primarily designed to supply short bursts of energy to quickly and reliably start an engine and then promptly be fully recharged. Starting batteries aren’t designed to be deep-discharged and then recharged – like a deep-cycle house battery – so a vehicle alternator’s voltage regulator is typically set at a fixed target voltage of between 13.6V and 14.2V, which is fine for this type of narrow application.

However, this voltage range is typically not high enough to fully recharge deep-cycle batteries following normal or perhaps even extreme use, especially if they’re cold. So, what if you want to use your engine’s alternator to also fully charge deep-cycle house batteries – flooded-cell, AGM, or gel – especially if these batteries are very hot or very cold? A three-stage alternator regulator – a.k.a. a “smart regulator” – may be the answer.

Like a smart plug-in battery charger or a multi-stage solar battery charger, a smart regulator features multi-stage voltage outputs (bulk, absorption, float) that may be user-selectable for different battery types (flooded-cell, AGM, gel). Really sophisticated smart regulators may even offer plug-in remote temperature sensors that attach to the battery case to allow the regulator to optimize target voltages based on the battery’s actual temperature.

For applications where the engine alternator is a prime recharging source, this suite of features allows for deep-cycle house batteries to be correctly and fully charged, resulting in both superior performance (usable Ah) and battery longevity (cycles). This is a primarily a marine application, as it’s well suited to hybrid “marine” batteries that are used for both starting and house applications, but there’s also some interest in the RV community.

Several companies manufacture smart regulators and other smart-charging system components that can be retrofitted to certain existing alternators and systems.

Give us a call at 615-285-0663, and we’ll be happy to discuss these and other possible solutions your particular battery charging requirements. Or visit our website.

About the Author – Jim Goodnight – also known as “crewzer” — is a retired solar industry application engineer, product manager, and forum moderator and has previously written for Home Power and Solar Professional magazines.

Choosing a Battery Isolator: Diode or Relay?


Most of our vehicles are equipped with a single starter battery at the factory, but some of us may want to add a secondary battery or two to power a winch, a compressor, extra work lights, an audio system, or to augment our camper batteries – or some combination of these – all without idling the engine.

But to do so, we usually have to take steps to isolate the starter battery from the secondary battery so that our vehicle will start when it’s time to head home.

A larger alternator is sometimes required as well.

One solution is to plug an extension cord into a vehicle’s seven-way trailer connector and use the battery charging circuit to charge the secondary battery. Modern trailer battery charging circuits are deactivated when the vehicle ignition is switched off, so the starter battery is isolated from the secondary battery and can’t be discharged by outside loads.

A Y- adapter would still allow a trailer to be connected to the tow vehicle. A possible drawback, however, is that trailer battery charging circuits are limited to 30 A. This may not be enough to charge several batteries and run other major DC loads, such as a three-way refrigerator.

More common solutions employ a diode or a relay isolator, each with its own pros and cons. A diode isolator installs between the alternator and the batteries; the built-in diodes allow the vehicle alternator to charge both batteries but otherwise keep them electrically isolated.

This configuration allows for loads to be connected to the secondary battery without discharging the starter battery. Medium- and high-current diode isolators for one alternator and two or three batteries are readily available.

The diode isolator pros include being easy to install, all passive, no moving parts, and therefore very reliable. Its cons are that its heat sink is relatively large (especially for high-current models), and the voltage drop across the diodes can reach ~0.7V, which could result in undercharging the batteries.

However, the alternator field sense line can be relocated to an isolator output, and the alternator voltage regulator will adjust charge voltage accordingly.

An isolator relay also installs between the alternator and batteries. Like a vehicle’s trailer battery charge circuit relay, a relay isolator is closed when the vehicle ignition is switched on, allowing both batteries to charge. When the ignition is switched off, the relay opens, and the secondary battery is isolated from the alternator and starter battery.

The relay isolator pros are that it’s relatively small, which makes it easy to locate, and there’s no voltage drop across the contacts. The downside is that it must be wired into the vehicle’s ignition circuit, it contains moving parts, and the relay contacts are prone to pitting and wear from the high DC arcing when the contacts are open and closed.

One of these approaches might be just the solution you need. Give us a call at 800-621-1271, and we’ll be happy to further discuss how the right isolator can help meet your power requirements without discharging your vehicle’s starter battery. Or visit Inverter Service Center for additional battery management needs.

About the Author – Jim Goodnight – also known as “crewzer” — is a retired solar industry application engineer, product manager, and forum moderator and has previously written for Home Power and Solar Professional magazines.