Solar Panels

You might also think outside the box when doing this. Once you start seeing you are able to replace your present daily battery usage with the solar panels you most likely will want to start doing other things with your trailer that consumes more battery.

You may want to plan your solar install with some expansion in-place.

We have to fight the generator use restrictions here on the East side of the US and never can you find a public camp place that allows us to run our generator after 8PM. This forces you into going more GREEN with LED lights and bigger battery banks and using Inverters. I started out with a 300WATT PSW Inverter setup to power up a few 120VAC home entertainment electronic items for just a few hours each night. It wasn't three or four trips when the wife wants more 120VAC items to use camping off the power grid. I went to a 400WATT PSW Inverter and eventually ended up with a 600WATT PSW Inverter setup. This does great for us now and runs my current used 255AH battery bank down to around 50% charge state at 8AM each morning when we are usually allowed to run the 2KW Honda Generator to allow the trailer on-board smart mode converter system to re-charge the batteries in a short three hour generator run time.

We have been camping off the power grid for around five years now doing this method...

I too am just now wanting to add solar panels to help out and it appears with room I have available on my OFF-ROAD POPUP roof that two 100WATT Panels on each side of my fantastic fan on the front of the roof and a 230WATT panel on the rear of the roof between the off mounted air conditioner and the end of the roof will really help out keeping me from running the generator so long each day. With my present daily consumption I still may have to run my 2KW generator for a hour or so to get the initial 50AMPS plus high current charge into the batteries and then let my SOLAR PANELS normal SUN RUN for the day complete the battery bank charge back up to their 90% charge state before i lose the high sun.

This is required for my somewhat higher battery power demand than alot of folks normally do.

Like everyone says each one of us is a little different in what we do so it takes some good planning to be successful about it.

Calculate all of your usage in AMPHOURS and what ever you pull out of the batteries you have to put back in... If you have to have a good 90% charge state before each evening like I do it may take a bigger solar panel install. In my case if the solar panels are not going to get my batteries back up to their 90% charge state each evening before I start my run off the batteries I have to plan for allowed time to run my generator when I am allowed to run it due to the generator run time restrictions.

I think you may also find that using solar panels to totally replace a generator is going to require alot of solar panels so as in my case I want to only use the solar panels to enhance my generator use. Also if it is cloudy everyday for a week the generator is the only thing that is going to work for you keeping the batteries re-charged.

Its all about PLAN Bs...

Roy Ken

The "best system" is the one that meets your needs and your needs sound fairly light for a pair of 6v batteries. Replace those light with some inexpensive LEDs and you use very little at all.

We use a single 230w panel and even with it flat we never needed our generator this year. We do have LEDs but the day and night furnace use more than offsets the power savings.

Now if you are going to want to recharge thos batteries in a day, West is right for a good sunny day. Add another panel for the not so perfect days or those shorter winter hours.

BTW figure out how to answer the questions about usage etc. that these guys ask and they can really help you set up a system. I tend to lean to overkill because once you stop worrying about the power, you tend to use more.

Here is a simple flow chart.

Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT.

For a nice explanation of solar, try this link: Golden rules of solar

By the way, you did ask about the "Best" solar system.

I saw one RV built on a 3 axle International chassis, and it had 16 each 200 watt solar panels on the roof. No A/C up there, or any roof vents, just solar panels.

That is the largest possible solar system you could put on a RV, and still keep the solar panels within the maximum 40' long and 8.5' wide roof system. They have the ability to carry over 300 pounds of batteries, and did. They also had a larger than average inverter to run the A/C unit and other 120 volt stuff inside the RV.

Even while in England, with it's much less than sunny conditions, they had great battery power, and could not plug into the local 220 volt RV park power systems to recharge or run the microwave and other appliances on board. So they relied on their solar system a lot while driving through Europe.

Fred.

Assuming that your 6 volt batteries have a total of 220 AH and that you are discharging them to a SOC of 50% every day, you'll want to have charging that will put at least 120 AH back into the batteries. A realistic module total would charge 5 hrs. at 20 amps, the remainder coming from the shoulder hours of the day at a lesser charge. 2 x 230w-250w modules and an MPPT controller with 30 A rating would accomplish this. Alternatively, 5 x 100W modules and a PWM controller would do it also. The choice would depend on roof real estate and any shade conditions if parked at a fixed location.
The best recommendation to specific brands would be a Rogue 3048 controller and 2 x Sharp modules.

My feeling is that you may be able to get by with less hardware if you calculated what you actually use for power. Here is a downloadable spreadsheet that will help calculate your needs.

Hi,

I have a E-meter in my motorhome, so I can track how many amp hours I use in a day. Running just the refrigerator, CO and propane leak detectors will use up about 35 amp hours per day. Add to this about 1 amp hour per light per hour, 4 amps to run a TV set, 2 amps to run a computer through a inverter per hour, and you can get a idea of what size system you will need.

A single 120 watt solar panel will make up about 35 amp hours per day and take care of the "House" load. Then add a second panel to take care of lights, 2 hours of TV or computer use. If you want to run the furnace a lot, it can use 6-7 amps per hour, or 35 amp hours during a cool winter day - with the heater set to about 60F overnight.

What I use is a Olympic Catalytic safety heater. 6,000 Btu's will heat my 30' motorhome to about 70F inside when it is above 32F outside. Below that temperature, I will need to run the furnace to re-distribute the heat and also warm the bedroom, and keep it at 70F. But I only need to run the furnace about 1 hour per day.

The water pump uses a in-significant amount of power. While it will draw 7 amps per hour, it also pumps 2 gallons per minute, or 120 gallons while using only 7 amp hours. So if you only have a 60 gallon tank, then it will only use 3 amp hours to pump it dry or less than 1 amp hour per day.

So my suggestion is looking at this website. SunElec.com and look for 12 volt nominal solar panels, and a 10 - 30 amp PWM controller. Check the size of the 85 to100 and 150 watt panels (length and width). Then go up on the RV and see what will fit around the A/C and roof vents, antenna, and other things up there. You might need to buy one 100 watt for between the shower skylight and edge of the roof, and a another size for someplace else.

While it is "Nice" to have or 4 panels the same size, it is not required.

For wiring, I used #10-2 UV resistant grey wire, Home Depot.

FOr panel mounts, I cut 6" long 2" angle aluminum channel, and drilled 3 holes 3/16" for the roof side and #10 screws into the roof (with lots of roof sealant to keep it in place and dry under it. 1 hole 5/16" to a hole into the solar panel.

I mounted my controller in the bedroom closet, and ran the wiring behind the refrigerator vent.

Good luck,

Fred.

Buy a hydrometer and after a typical day/night use measure the SP and then lookup the SOC. Lets say it's 25% discharged and your batteries are 230AH. Since you used 57AH that would be a starting point to size the solar system.

A 140W panel might produce 10A in an ideal condition lets say for 5 hours. That's 50AH and since ideal doesn't happen lets say you get 25AH. You need 2 of those panels.

I would like to get the best solar panel recharge system out there.

For you 1 panel might be the "best" or perhaps 4 panels. There are many variables.

I have one of these 100w panels. We went 7 nights without running short of juice. Battery completely recharged each day, even with a complete day of heavy clouds. Similar use to what you describe.

I will put one on my next unit (hoping to upgrade this winter).

I have 2 six volt batteries in line and want to keep them charged by solar power over one day of average sunshine...that is...partly cloudy. I run a propane FA and regular trailer lites inside and small water pump.

That question is way to open ended. Solar systems are all different, each built to a specific owner's needs. What are yours?