Our electrical system

However, that was in the summer when our furnace wasn’t necessary and in a place where we could run the generator as much as we wanted. We ran the generator about five hours a day – two in the morning and three in the evening. We didn’t realize that wasn’t very practical at the time. Sometimes we are slow learners as we ran through two forty pound propane tanks pretty quickly by using the propane generator that much. 🙂

In my research, I found that most experts agreed that two 6-volt batteries are better than single 12-volt batteries because the combined 6-volt batteries have more amp hour capacity and their longevity is better. The downside is that they are larger than 12-volt batteries and that can be a big issue for RVers when deciding their placement.

Also, my research shows that most experts say AGM batteries are better than the less expensive wet cell batteries. They are maintenance free (no checking and adding of water). They don’t have to be vented. They resist shock better – a very good thing in an RV. And they can be placed anywhere, even on their sides. According to my research, the only reason not to buy AGMs is price.

We originally thought we would mount our batteries on their sides in a small compartment and that was a factor in our decision to go with AGMs. Ultimately, we decided to put them in our main basement compartment since we had the room and it would be easier to do all the wiring. However, even had we known that, we most likely still would have gone with the AGMs.

So that’s the main reason we selected the Xantrex RS3000 over other good inverters/chargers. Other reasons were that this inverter is a sine wave inverter and that it has an excellent three-stage charger (bulk, absorption, & float) to keep those sensitive batteries charged and charged properly. Many other top inverters had those features, but they could not be wired inline to our 50 amp circuit.

The TriMetric monitor is what allows us to know how many amp hours we have used and how many actual amps we are using at any particular time (we can test each appliance individually to determine the amps it uses). The TriMetric keeps us from discharging the batteries too far and thus we can extend their lives. It is the one thing we look at constantly to manage our battery usage.

And that ended phase one of our electrical upgrade. We were pretty sure that it would be a long time before we did phase two and added solar panels. After all, we would not be boondocking very much and when we did, a 600 amp hour battery bank should be plenty and we could re-charge the batteries quickly with our generator if we didn’t have shore power for charging.

Each morning we would run our generator to try to charge our batteries back to full capacity. What we soon learned was that the generator would get us to about -100 amp hours before the inverter/charger went into "absorption" mode and slowed down the charge to the batteries. The generator sucks down propane and it was just too expensive to run it to charge the batteries at the slower absorption rate.

Basically, we were getting cheated out of a third of the battery capacity we were willing to use. It quickly became clear why solar panels are a good idea. They could get us back that extra 100 hours of amp hour capacity. Plus they could charge the batteries throughout the day and offset some of our daily use keeping our deficits from getting too high.

I’ll admit I didn’t do a tremendous amount of research here. My little bit of research showed that panels were not all that different in the big picture. They are rated by watts of output based on standard testing conditions. Note however, that the experts say "real world" conditions are much different than standard testing conditions, therefore we can count on only about 80% of the watt-rating of the panel.

We ordered the Heliotrope HPV-30DR MPPT (Maximum Power Point Tracking) solar controller ($293), the accompanying solar monitor ($158), and four AM100 solar panels ($1,980 or $495 each) from AM Solar. The total cost of the equipment plus mounting brackets & screws, wiring, and shipping was $2,994. Add to that about $50 for additional wiring and connectors and Phase 2 cost $3,044 (April 2008).

In our case, that would mean 600 watts of panels to go with our 600 amp hours of battery capacity as explained above. But I didn’t want to spend the money on six 100 watt panels, especially for the relatively small amount of boondocking we would do. We decided to go with four panels and rely somewhat on the boost (discussed below) provided by the Heliotrope controller. If we decide we need two more panels later, we’ll get them – we have roof room for a couple more.

I’ll try to explain. Solar panels generally operate at 17 – 18 volts. AM Solar claims up to 21.5 volts for their panels. But the optimum battery charging voltage is about 14 volts. The MPPT controller somehow converts the higher voltage down to the 14 volts. With our Amps = Watts / Volts equation, the amps produced goes from approximately 5 amps per hour per panel (100 watts / 17 to 21 volts) to about 7 amps per hour per panel (100 watts / 14 volts). So there is a "boost" provided by the technology of the MPPT controller and more amps are pushed into the batteries.

See the gray metal box to the right of the system panel? We wired the incoming cables from the roof through that. It’s a "pull fuse" whereby we can take the controller out of the circuit if we need to for any reason. So the wires come in from the roof and go into the fuse box on the left. Then they go out on the right and they are attached to the positive and negative hubs on the panel.

Once the controller and monitor were in, we set the four solar panels on the roof. We made sure they were spaced just right. We favored them slightly to one side to give a little walkway, and so they would be more toward the driver’s side to avoid low hanging branches on the side of the road as much as possible. We also made sure they would not be in the shadows of the vent covers, the air conditioner housing, or the satellite dish.

It will take us at least ten years to recover our investment. It will be shorter for serious boondockers, but an electrical and solar upgrade is a lifestyle choice and it’s really hard to justify financially. There is no question you can get more use of it in the wide open spaces of the west where there is more public land, but if you spend most of your time in the east, it becomes even more difficult to recover costs.

At the end of 2013, we just replaced our Lifeline AGM batteries as we were noticing a loss of capacity. By running our generator more and spending time in the east (where we boondock less), we probably could have extended the use of our batteries another couple of years. However, we decided to go ahead and replace them so that we would have full capacity going into 2014.