A Powerful Transformation


Assembling and installing the ultimate solar system for independent travel with the help of energy experts, AM Solar

The sun is a gigantic mass in the solar system that everyone expects to come up in the morning and to go down in the evening. It’s the Earth’s temperature regulator and is worshipped by many who enjoy basking in its warm glow for recreation. For most, the sun’s power is generally accepted as just part of daily life, but for RVers who relish getting off the grid, the sun is nature’s power generator.

Solar systems that harness the sun’s rays and turn its energy into electrical power have been around for a long time, and RVers who appreciate the seclusion and economics of primitive campgrounds have embraced this silent power for many years. New, and continuing, technology has leapfrogged solar power to new levels, and RVers can now build systems that make living off the grid more practical than ever. We assembled and installed a robust system using the latest equipment available at the time (this technology changes rapidly) with the help of the experts from AM Solar in Springfield, Oregon, that transformed the RV into a mini power station.

[1] Remote panels for the MagnaSine Hybrid inverter (left) and Blue Sky Energy IPN-ProRemote charge controller (center) were mounted in a cabinet that was clearly visible. Both these panels provide detailed programming to fine tune the system for optimum performance. Users have incredible control over functions, but programming must be initially set by the installer — and users should resist making changes that could damage the lithium batteries. Ring around reset button (arrow) illuminates red when batteries are outside threshold voltage to prevent damage.


[2] Battery bank is built from individual 3.2-volt cells that are banded together in parallel to make a super cell.


 [3] Four super cells are connected in series using copper straps for the 12.8-volt, 300-amp-hour capacity required for this system. Batteries can be configured in a number of footprints.

While the attributes of a solar system, including electrical independence, are well-established, a primary benefit is to properly condition batteries. Solar power, through a well-designed system (which includes a good charge controller) offsets continual deep discharges because the batteries are constantly being conditioned in response to actual usage. In the end, lead-acid batteries, for example, can last twice as long. At today’s prices for batteries, that’s a big savings.

Preplanning is crucial to building a good solar system; you just can’t slap a bunch of components together and expect positive results. The first step is to figure out your needs based on how you use the RV. In our case we determined that we wanted enough power to run the microwave, induction cooktop, hair dryer, fireplace flame (for visual ambiance), entertainment systems and all the other 12-volt DC accessories in the rig, and, of course, condition the batteries properly. Our goal was to build a system big enough to allow complete independence from the grid unless we wanted to run the air conditioning. It’s not practical to set up a solar system to continuously power the air conditioner(s) and in our case we rely on LP-gas to run the refrigerator. Systems can be designed to handle a residential refrigerator, but the battery bank and number of panels must be increased.

Our original calculations had us settling on three 160-watt solar panels, two AGM batteries (300 amp hours), a 2,000-watt inverter/charger and a controller with a boost feature. After discussing our needs with Greg Holder at AM Solar, we made a number of changes and upgrades. It kind of reminded me of remodeling a stationary home; changes are inevitable.
In the end we upgraded to four 160-watt panels after learning that the extra wattage eliminated the need to tilt the panels to follow the sun. That was a big selling point, since we would rather not spend too much time on the roof. The biggest upgrade was to lithium batteries, which upped the price tag considerably. Then to condition the lithium batteries properly, we upgraded to a Magnum Energy MagnaSine Hybrid inverter/charger.

When all was said and done we had assembled a very powerful system with all the bells and whistles, banking on optimum performance and long-term reliability. It also satisfied our secret desire to have the ultimate system for our needs.

[4] Mini battery management system (BMS) circuit boards are wired between cells. These boards send voltage information to the master control box. Low or high voltage will shut down the system.

 [5] When complete, yellow wires are used to connect the mini BMS boards to each cell in the battery bank. Red lights on the board flash when the system is working properly. Plexiglas in wood frame is used to protect the top of the battery bank. Clear Plexiglas is used to allow for visibility of the flashing red lights on the mini BMS boards.

The Batteries

Lithium batteries are no longer science fiction; use in electric cars has made lithium batteries very popular and for good reason. They last a really long time and can handle many more discharging/charging cycles than their lead-acid/AGM counterparts. These batteries maintain rated performance when taken down to the maximum depth of discharge, which is an amazing 80 percent. Lead-acid and GM batteries should not be discharged beyond the 50 percent threshold.  

To put the performance numbers in perspective, the lithium batteries used in the test system will provide 240 amp hours before recharging versus 150 for the lead-acid or AGM batteries. An even bigger consideration is voltage. As the charge level in lead-acid and AGM batteries decreases, so does voltage, which impacts appliances and accessories. Lithium batteries maintain full voltage until fully discharged, and then voltage drops precipitously.

Because the performance characteristics of lithium batteries are so much different, a battery management system (BMS) is critical to prevent damage from over­discharging or excessive voltage. Mini BMS circuit boards are wired between cells and these boards are tied into a master BMS control box. Red lights on each BMS cell-level board flash when everything is OK. Four mini BMS boards were used on the battery bank built for this system.

When the BMS recognizes that the high- or low-voltage threshold has been breached, it automatically shuts down the battery bank, well before any damage can occur. When that happens the light around the reset button mounted inside the RV illuminates to inform the user there’s an issue with voltage. If any of the mini boards discover a change in the threshold voltage — high or low — in any cell, the entire bank is shut down.

[6] A test light is used to identify 120-volt AC circuits that will be powered by the inverter and how they relate to the breakers in the power distribution center.

 [7] Never rely on the breaker labels, which can be mismarked, as they were here.

 [8] Electrical J-boxes were used to make the 120-volt AC connections necessary to insolate the accessories that were targeted for power by the inverter.

[9] A secondary power distribution box with circuit breakers was installed in the system. This provides circuit breakers for the appliances and outlets that are wired into the new solar system.

[10] Existing terminals that come with the prewired solar panels are cut off and the wire leads lengthened using butt connectors.

[11] Ends of butt connectors are heat shrinked around wire, providing a weathertight seal.

Building a battery bank from lithium cells is not designed for the do-it-yourselfer. There’s a lot of science behind assembling the bank and that should be left to the professionals. The batteries are assembled using individual super cells that are rated at 3.2 volts and 100 amp hours. These super cells can be configured to offer greater flexibility when looking for space to house the battery bank, unlike conventional deep-cycle batteries that have established dimensions.

For our system we paralleled three smaller cells into a super cell and then put four super cells into series using copper plates to make a 12.8-volt, 300-amp-hour battery bank. Once the batteries were configured and banded they were initially electrically balanced so the voltage is consistent and at a full charge. This step requires the use of a sophisticated charger that can be controlled accurately.

Normally, lithium batteries are rated for around 2,000 charge/discharge cycles, which in itself is much better than the 500-1,000 cycles expected of a lead-acid or AGM battery. AM Solar tunes its proprietary BMS so that it operates in a narrower window than the maximum and minimum voltages established by the battery manufacturer, which increases the expected charge/discharge cycles to 3,000-5,000. If the user discharges the lithium batteries 80 percent 365 days a year (which almost no one will do), the batteries should last 8-13 years. Given a more practical use of the batteries in normal living circumstances, the batteries should last at least 15 years, which makes the $2,599 price tag a lot easier to amortize.

Lithium batteries will not discharge much when in storage, and after testing for five months with no external charging support, the voltage barely changed. Another welcome feature is that lithium batteries do not have to be fully charged each time. That means you can charge them to a certain point (if there’s little sun or electrical power is not available) without negatively affecting conditioning. Lithium batteries can be charged very quickly.

When compared to batteries of equal capacity, the lithium counterparts are smaller and lighter. Each cell weighs only 7 pounds, which means the entire battery bank for this system weighed only 84 pounds, less than the weight of one 6-volt AGM battery.

Undoubtedly, bad press that surfaced a while back created some discomfort when considering mounting these batteries inside an RV storage compartment. Fires, created by battery overheating, were once a problem. The batteries under scrutiny were Lithium-Cobalt Oxide formulations and were subject to thermal runaway hazards that led to fires. The newer crop of batteries is Lithium Iron Phosphate, which is basically noncombustible. Combine the latest generation lithium batteries with a solid BMS and the system becomes very safe.

The Panels and Charge Controller

Solar-panel technology has moved very fast in the past few years. AM Solar specializes in the most up-to-date products and for this installation used its SF160, 36-cell mono-crystalline panels. All the panels custom-built for AM Solar and owner Greg Holder specify at least 36 cells so they are large enough to capture the most energy. The panels operate at 18 volts and are rated to have an 8.8-amp output. They measure 26 3⁄4 by 58¼ by 1 3⁄8 inches, which is very compact considering the output.

Higher voltage boosts the charging amperage, especially when routed through a Blue Sky Energy Solar Boost 3024iL controller, which is designed to lift the charging amperage to the highest possible level. The controller is a critical component in any solar system. Its main function is to regulate the charging current and prevent overcharging the batteries. The unit used here is rated at 40 amps, so there’s a little room for expansion on the system, which will likely not be needed. This is a very sophisticated controller and it features a relatively new feature called Maximum Power Point Tracking (MPPT). This gives the controller the ability to boost the charging current (amperage) by converting some of the excess voltage coming from the panels — thus the reason for panels that operate at a higher voltage. The biggest boost can be realized when the panels are cold and the battery voltage is low.

[12] In typical AM Solar fashion, all wire leads on the solar panels are secured with cable tie mounts that have been fitted with 3M VHB adhesive tape.

 [13] Mounting brackets are bolted to the frame of each solar panel. They provide enough clearance off the roof to allow for good air circulation. They can also be fitted with hardware for tilting.

[14] Cardboard used to pack the solar panels in the shipping boxes is used to configure mounting positions on the roof. This provides a great visual of how the final installation will look — and keeps clear of any roof obstructions.

 [15] VHB adhesive tape is applied to each bracket foot, which can be adjusted by the knurled knob.

 [16] The tape provides a very strong bond once the roof is cleaned with alcohol …

… but must also be screwed into the substrate on a rubber membrane [17]. The VHB tape is actually strong enough to hold the panels on a fiberglass roof.

The controller was tied into a Blue Sky Energy IPN-ProRemote panel that has a tremendous programming capability. Five levels of information, deciphered by the various algorithms in the controller, can be read on the remote screen. The information is extensive, including the ability to equalize the batteries, which is not needed for the lithium batteries. It’s important to allow the installers to set the controller and provide you with the do’s and don’ts to keep from getting in trouble with lithium batteries.

Beyond voltage, the information shows how long since the batteries were fully charged, amperage from the solar array, usage in amp hours and much more. If you’re a power watcher, you’ll be in heaven here.

The Power Inverter/Charger

An integral part of any complete solar system is the power inverter/charger. This component provides the power from the batteries to run the targeted 120-volt AC appliances and accessories and charge the batteries when hooked up to RV park power. We chose the aforementioned MagnaSine for its established reliability in the industry, to provide pure sine-wave power for all of our sensitive electronics and, most importantly, its compatibility for use with lithium batteries.

The model MSH3012 is the only inverter in the Magnum Energy line that has the hybrid feature, which provides a relatively new twist on inverting power by working in concert with 120-volt AC power when connected to some type of shorepower. Without getting too deep into the electronic wizardry, the MagnaSine inverter provides load support when there’s not enough current to operate the desired systems. For example, if you find yourself visiting relatives and can only plug into 15- or 20-amp household power, it’s not possible to run the microwave and hair dryer at the same time (depending on the demand from other appliances). The hybrid feature will provide the extra called-for current to operate the other appliances up to the rating of the inverter, which in this case is 3,000 watts. This will prevent breaker tripping and an abrupt loss of power.

Normally, other inverters operate only on one source of power to run the appliances and accessories and use a transfer switch, which isolates the inverter when plugged into an external source of 120-volt AC power. The hybrid inverter uses energy from the battery bank and an external 120-volt AC source to power the loads; any surplus power can be used to charge the batteries or handle higher loads than the AC input alone can provide.

Controlling the inverter is done through a remote with an LED display that we installed next to the IPN-ProRemote for the solar panels. The panel is loaded with features, and again, takes some initiation and practice to run through the steps. It really allows the user to fine tune the system to take full advantage of the lithium batteries and other power sources like a portable generator while boondocking. The output of the generator can be dialed in using the remote panel, which adds greater flexibility when charging batteries and running appliances. Since the MSH3012 inverter can add up to 25 amps to the output of the portable generator for a period of time, it’s possible to run the air conditioner while using a 2,000-watt generator long enough to cool down the interior and remove excess humidity. Once the heavy load is eliminated, the generator will recharge the batteries through the inverter.

The Installation

Installing a system of this caliber is not for the faint of heart. I highly recommend leaving it to the experts like AM Solar because of the many intricate pieces that need to be assembled. For example, it took the better part of a day just to locate a suitable runway for the 4-gauge cables used to connect the panels to the charge controller.

[18, 19] Self-leveling sealant is used around the brackets and must cover the screw heads to ensure watertightness.

[20] The 4-gauge cables were previously routed near this roof vent and connected to the proper terminals in the connection box before it was screwed to the roof. A generous helping of sealant was applied to the roof, under the box, to make sure the hole needed to route the large cables is watertight. The wire leads from each panel are then connected to the terminals in the connection box.

It took 4½ days to complete the installation to satisfy all the required codes, ensure that all the components were secured properly and that the wiring was meticulously routed and wrapped.
As one might expect, the cost of such a robust solar system is not inexpensive. The complete package described above with all the ancillary pieces like the circuit breaker, fuse, BMS and cables was just shy of $12,000.

The Results

Obviously, the results from any solar array will be subject to the time of the year and personal usage. On an average day, we consume about 100 amp hours, which is less than half the capacity of the lithium battery bank, and we usually have our batteries fully charged by noon when in good sun. The fact that the lithium batteries do not require a finish charge provides great versatility on days when the sun is not as strong.

Except to run the air conditioning, there’s really no reason to hook up, which gives us exceptional freedom to travel at will. We jokingly tell our neighbors that we can sell energy back to the grid, which always initiates a conversation and tour of our system.

For More Information

AM Solar

Magnum Dimensions


DSC_0514 [21] All the cables from the solar panels and breaker boxes are routed to the designated compartment that holds the components of the system. Here, the Blue Sky Energy charge controller is being wired before mounting on the wall.

 [22] The MagnaSine Hybrid inverter/charger is very heavy and requires precise mounting to keep it from moving when the RV is on the road. There must be 6 inches of clearance around the inverter to allow for proper ventilation, which relates to optimum performance and safety. A 3⁄16-inch aluminum plate was cut to size, painted and bolted to a metal frame inside the storage compartment to which the inverter was bolted. DSC_0500

DSC_0597 [23] A weatherproof, 50-amp breaker is used between the solar panel connector box and charge controller.

[24] Master cutoff switch is used between the battery bank and the inverter and charge controller. Next to the switch is a solenoid that is triggered by the master BMS control. If any one cell falls below or exceeds the voltage threshold, it cuts off power from the battery bank. DSC_0605

DSC_0608 [25] Master BMS control box is wired into the system and attached to the wall. The BMS is necessary to make the lithium batteries function properly and safely.

 [26] When complete, all the components are neatly in place for accessibility and service. A separate fuse and cutoff switch is used between the inverter and the batteries. DSC_0615

DSC_0617  [27] A solar meter is used to determine sun strength. By pointing the sensor at the sun at the same angle as the solar panels, the meter will read out the percentage of sunshine reaching the cells in the panels. Here it was early morning and the panels were getting 38 percent of the sun’s potential.

 [28] Panels are neatly arranged on the roof with most of the wiring concealed. The only maintenance is to keep the panels clean. These solar panels are very durable and are expected to last 35 years. They are rated to withstand 125 mph wind loading, hail up to 1 inch at terminal velocity (52 mph) and more heat than can be found on Earth. DSC_0646




























































  1. Kudos for a well-written, well-photographed article detailing a high-quality, cutting-edge RV solar system! There are so many poor writeups of poor-quality RV solar systems with old tech (using short-lived flexible solar panels and heavy, inefficient flooded batteries), it’s great to see a description of a solid system with all the details.

    One thing I’m wondering: what is the temperature sensitivity of that battery bank? I have read that many lithium chemistries don’t like to be charged if below freezing. Is the bank in the RV cabin itself?




Please enter your comment!
Please enter your name here