Solar Panel Round-up: what wattage do you have?

[rob_gendreau]

1. 100W panel from Grape Solar. Made a portable mount; carry it in van and hook it up via extension cord to MPPT controller in the van so that it can be positioned up to 25' from the van. I also have an Instapark Mercury27 very portable panel, 27W. That gets connected via a Sunguard controller to the DC system cig plug on occasion.

2. The 100W is more than sufficient; I have a small Norcold and pretty much all LED lighting. The batteries are ancient AGMs, two Type 27s with about 180AH. The 100W can fill those pretty well, even with the refer running in a hot climate. Increasingly I have a rat's nest of li-on batteries to charge: phones, tablet, camera batteries, flashlight batteries, etc. Hard to tell how much of a load they are, but I suspect it's not completely insignificant these days. I often charge those on the move though, since I have power then and since that way all the wires don't get in the way.

3. 2001 EB.

I'd add that the measly Mercury27 worked a champ, even for the van. I got it to directly charge USB-powered devices (it has 2.1A USB controller built in) but I hooked it up for charging 12v via an older controller I had. It's only about 18v, but it sent about 1A at 12.9V to the system, which provided a bit of a boost, and kept my battery at about 85% for a few days while parked with the refer running in 85F heat (hotter in the van obviously). Point being that every little bit helps.

[rallypanam]

1. 300W total - three 100W grape solar/renogy panels with a 200ah Universal 4D AGM

2. I don't think I'd be happy until I could park in the shade in 120 degree heat and keep my beers at 34 degrees in perpetuity.. but otherwise, it's sufficient.. If I can get some sun every day, it'll keep the battery full or close to full.

3. EB50. Most usage by far is the fridge. Second most is LED lights. Third is Suburban propane furnace, couple of times a year.

[pinz712]

I have one 300w 48v panel on the roof. With Correct charge controller

2 Trojan deep cycle 6v battery's on the driver side frame rail.

Harbor Freight Inverter for running the microwave and other 120v battery chagers.

We can run the Truck Fridge continually during the summer and 80% of the time in the winter.
(we stopped doing that because we added a grid tie and turn our house meter backwards)
Very happy with it During Burning Man we charged the E-bike and all of our AA's every evening by the 10th day it could not keep up we dropped it to low PS it was really dusty it was only doing like 2 amp.

[JJSporty]

1. How many total watts of solar panel(s) do you have? And how many amp-hours is your house battery?

We have two 100 watt Zamp solar panels for a total of 200 watts mounted to the factory rails on the roof by SMB West. We have a Zamp controller installed by SMB West, as well as two 90 Ah group 27 UB12900 AGM batteries in our battery bank for a total of 180 Ah also installed by SMB West in the original build. The two solar panels are hooked up in parallel with 10g wire throughout the solar charging system.

2. For your power usage, have you found it: insufficient, sufficient, or more-than-sufficient?

In most situations it has proven sufficient so far. We rarely connect to shore power and are usually good for a few days with moderate to good sun. Lighting is all LED so our main draw comes from the Norcold 2.7 cubic foot refrigerator, Espar D5 Hydronic furnace/water heater, Fantastic fan, water pump, and 22 inch TV/DVD player. We usually run the engine on high idle option when using the 2,000 watt Magnum inverter/charger to run the microwave for more than a few minutes to offset the massive draw on our battery bank. Running the engine on high idle often depends on the state of our battery bank, how long we are going to use the microwave, how sunny it is, and whether we are planning on driving a sufficient distance to replenish the amps the next day.

3. Describe your power usage and give the model of your vehicle (mostly so we know what size space we are talking about lighting up, heating (if electrical), etc.)

Overall we are relatively miserly electrical power users. We come from many years of van camping and spend most of our time outside the van other than on travel days. We do our best to travel in mild climates often in the southwest. We do plan to do more traveling in the northwest in the fall and spring so we’ll see how well the 200 watts of solar performs under less than optimal sun conditions.

We’ve had two VW bus campers, a Coleman tent trailer, and a 2006 Ford SMB with a PH before our current SMB. Electrically speaking, the VW’s and the tent trailer were relatively primitive. A 12 volt car battery and flashlights along with a Coleman lantern were what we worked with. Our 2006 SMB seemed pretty deluxe in comparison. We equipped our 2006 SMB with a Zamp 120 watt portable setup which worked relatively well but was insufficient to sustain the vehicle demands for more than a few days without driving. It had two group 27 AGM batteries like our current setup but the 120 watts was a little underpowered. They just couldn’t deliver enough power to keep from slipping a little each day. In spite of this, I learned a lot about the demand and production sides of using solar.

Currently, we have a 2014 RB Sprinter high top built by SMB West and love it. We got it in January and have put over 11,000 miles on it in ten months. We have been quite pleased with our solar and battery setup. If I had to describe it in a few words, I’d say it’s well balanced for our needs. This being said, we have been considering adding another 100 watt Zamp solar panel on the roof for our northwest travels to try and compensate for a generally less sunny climate. I hope this helps folks figure out what would work best for them.

[JJSporty]

I thought I’d write a second post on this topic to summarize the basic steps I’ve learned from reading a few books on designing an effective RV solar charging system. I’m not an electrical engineer or an expert in the RV solar field. This is only a brief overview and isn’t intended to replace professional guidance. By outlining these few steps that the experts seem to agree with, it might help others in designing their own effective solar charging system.

Step 1 – Determine your power need: Every person will have a different need for powering their electrical devices. The best way to do this is to make a list of all the electrical devices you plan to power with their amounts of electrical consumption and estimated amount of time they will be running on a daily basis. For example, a refrigerator may require 3 amp hours per hour to run but it may only be running a third of the time so 1 amp hour per hour times 24 hours might be a good ballpark estimate of the amount of electricity required for that device. You need to do the same for all your other electrical devices to arrive at an estimated power consumption total per day.

Step 2 – Determine your storage need: Using the total estimated electrical consumption from Step 1, determine how much battery storage you are going to need per day. Based on my research, the experts strongly recommend not discharging your battery bank beyond about 40% on an ongoing basis. According to the experts, deep discharging will dramatically shorten the life of your very expensive batteries so be mindful of this when designing your solar charging system. You want to design a system that draws off the top third or so of your battery storage capacity. So, if you need 60 amp hours a day to keep your devices humming along and the campers happy, a minimum of 180 amp hours of battery bank storage capacity wouldn’t be out of line.

Step 3 – Determine your charging need: Step 1 will determine what you need to keep the campers happy, Step 2 will determine what you need to store to service Step 1, and this step will help you determine how much charging capability you will need to design an effective and balanced solar charging system for your specific situation. If for example, your calculations from Step 1 and 2 indicate you need to recover 60 amp hours per day to satisfy your electrical consumption need, you will need solar panels and a solar controller that can deliver this charging capacity per day. This will be the minimum Solar charging capacity you will need. In addition, you need to consider the amount of sun your solar panels will receive both in terms of time and quality. The effectiveness of solar panels can dramatically fluctuate depending on the type and quality of the panels and amount and quality of sunlight hitting the panels.

All this being said, I’m a huge supporter of solar. Personally, we adjust a bit from day-to-day if we don’t manage to capture sufficient solar goodness to replenish our battery bank. Since we often only stay in a place for a couple days, we can recharge while driving onto our next adventure. Once again, I’ve only provided these steps to help others try and better design their own solar charging system. This is a broad-brush approach and is only intended to serve as a beginning for folks for some sort of starting point in the design process. I’m sharing this because I’ve been there and feel like this is a sensible approach to designing an effective solar charging system.

[Viva]

Very good points, JJSporty. I would add to that a general/overall assessment of one's style (or combination of styles). Boondocking? If so, for how long in a row? Plugged in? Frequent long drives? These each have an influence on it as well. (And you did touch on this.)

Also, do you mind adjusting your style for the circumstances? Or do you want it to be "just like home" no matter what? What I mean is, say you like to use the microwave oven. Can that just be when you are plugged in or fully charged with good sun? Or do you want to be able to use it always, with less attention paid to the weather, etc. -- and not doing so would be the negative sort of "camping" feel that you don't like. Etc. etc.

[SixCardCharlie]

Does anyone have an inverter and a separate solar charger? Or is it more efficient to have both in one?

[REF]

I think you may be thinking of separate inverter/converter, no? A solar charger is a whole separate thing, unless there's a unit out there I'm unaware of. My rig had a converter for charging and running 110 outlets when plugged into shore power, I added a separate 1000w prosine inverter with a dedicated outlet to run things off of the house battery. I believe the magnum units SMB has been installing are both a converter/inverter, while good units, if one side craps out, you are looking at replacing the whole thing at a higher cost. I tend to go for separate components for that reason, if space allows. Kind of like the TV's with the built in DVD players that always broke or the DVD/VCR combo units...
BTW-I have 1 Kyocera 135W panel, while sufficient most of the time, I would add another if the roof real estate allowed. May go with a portable unit, like a zamp unit, to supplement when I'm in shade, extended stays or running both the fridge and Engel fridge/freezer.

[SixCardCharlie]

Sorry if my terminology is off, I'm still trying to familiarize myself with solar.

I have an inverter. I am wondering if I can get a device to let a solar panel charge my batteries and still allow me to use my inverter. or do I have to get a whole new unit?

[Scalf77]

They should and do operate independently of each other.
-greg