Solar again?

[Acampingwewillg]

Hi all
I know, Im sure this has been answered before somewhere here but what the heck. While I was just sitting being lazy today, I said why don't I go on top of the MH and measure some to see what kind of room I have up their. Well, between all the antenna's, air conditioners, vents and such, I came up with some figures.

After looking at dimensions of some of the larger 24 volt panels, it started to look like I might be better off with the smaller 12 volt 100-140 watt types. Anyways, it appears I may have room for 4-6 panels probably configured in 2 or 3 two panel groups. Im getting to the question.....would it be wise to series wire each set of two panels and then parallel, giving me 2 or 3 24 volt arrays? Im just in the "thinking" process now but since I took the first step to measure, may as well ask away....:B

We don't do a lot of dry camping/boondocking but I could do a lot more, I currently have (6) 6 volt batteries.

[westend]

Acampingwewillgo wrote:
Thank you for the Links and great info.....Id have to say one of the reasons I started to really consider Solar now is because of all the Price drops but it will still be a rather large project for me after looking at all the installs I viewed on another thread(quite impressive). Thanks again

I guess "large project" and different daily use are both individual but mounting a couple of modules and pulling wire can be fairly easy. The guys with a MH and all that basement space have the upper hand, a guy can mount all the devices and wires on a panel and slide it into a storage area, to be mounted. That right there takes a lot of work out of the process.

[hermy]

you are exactly right Royb- I'm sorry I sounded so high minded. What works for us is not what may work for others. Sorry.

[RoyB]

Hermy - Like I say I may have a different story to tell once I get back in the woods...

I use this BATTERY MONITOR PANEL to masure the DC VOLTs from each battery bank and a hall effect "donut" for the main 4AWG cable feeding my trailer from the selected battery banks.


With my present off-road POPUP setup My current meter shows me during the day run about 1-2 amps which represents my parasitic keep alive DC power drain etc..

At around 8PM in the evening I see around 20 or so DC AMPS (appx 250WATTS) beings drawn from the 600WATT PSW Inverter and other 12VDC appliances direct connected to the main battery switch. After around 11PM at night when we shut down for bed I can read my normal 1-2AMPS being drawn again on the AMPS meter.

Starting out with a 90% SOC battery bank which I get from running my 2KW Generator with the 30AMP shore power cable plugged into the generator 120VAC Receptacle using a RV30A-15A "long" adapter for around three hours after 8AM I can last until 8AM the next morning when I see the DC VOLTMETERS now reading 12.0VDC. They were reading as high as 12.6VDC right after I did my three hour generator run after 8AM.

SO what you telling me I should be able to get my 255AH battery bank back to its 90% charge state by lets say 4PM in the afternoon by just using one 120WATT Solar panel if the SUN is out all day long. The math says NO WAY... The 120WATT Solar Panel will be outputting 14.4VDC at around 5-6AMPS during this time period and of course this is what will be seen around high noon only. It will less on both ends of the day for the 5-6AMPS current.

I hear what you are saying but I suspect that I am pulling much more power all day/night long than you are. I know what I am drawing from monitoring my DC meter Panel.

What I pull out of the batteries in the 20 hours time frame will not be replaced by the 4-5 hours of 5-6AMPS coming from the solar panels... ???

If I did this method the first day I might make it ok without running the generator until the time we start kicking in our daily routine of 20AMP draw starting around 8PM that evening. I will see my DC Voltmeters drop down to around 10.5VDC in a real hurry and would have to completely shut down the batteries... Of course where we public camp here on the East side of the US we are not allowed to run the generators anytime we want too.

just saying..... We all camp differently...

Roy Ken

[Acampingwewillg]

Thank you for the Links and great info.....Id have to say one of the reasons I started to really consider Solar now is because of all the Price drops but it will still be a rather large project for me after looking at all the installs I viewed on another thread(quite impressive). Thanks again

[hermy]

People tend to make this solar thing way more complicated than it needs to be. Roy B... 2 120 watt panels on a pop-up? Seriously? What do you want to do- welding? We have a single 135 watt panel with 2 normal size 12 volts on a 34' fifth wheel. We can boondock indefinetly- 14, 20, 30 days without ever running the gen. We have a 400 watt inverter that allows me to run the tv and charge cell phones, computers etc. Yes, we are mindful of our power usage but we do what we want to do. My last set of batteries were still performing fairly well after 5 years so I don't think we abused them. We have installed similar sized systems on numerous friends rigs and they all perform very well.

[RoyB]

We do alot of camping off the power grid and want to run just about the same items we run at an electric site but of course no air conditioning or high wattage microwave. Also there will be times we won't be running the high battery drain associated with the Propane heater blower motor.

We are currently very successfully doing all of this with our upgrade to smart mode converter/charger, led lights, and more batteries.

The concept for us is to run all of the 120VAC items we want to run from a 600WATTS PURE SINE WAVE Inverter and run all the 12VDC item we want to run direct connected to the battery main switch.

With all of this planned out our battery bank drops to around 12.0VDC very morning around 8AM and then when allowed by the camp ground rules can run our 2KW Honda generator to re-charge our battery bank back up to its 90% charge state. Our battery drain is right at 20AMPS from 8PM to 11PM and the keep alive battery drain the parasitic drain is 1-2 AMPS all the time.

As stated above we are very successful doing this but have to start each day off with fresh 90% state of charge batteries.

I too am now looking into installing SOLAR PANELS... My OFF-ROAD POPUP trailer ROOF area can be fitted with two 120WATT SOLAR panels installed on each side of the fantastic fan location on the front part of the roof. I also have one other spot between the air conditioner install location and the rear part of the roof running across the roof for a 120WATT size solar panel. The 120WATT solar panels will only produce around 18VDC @ 5-6AMPS each (At high noon I presume) so these will connected in parallel and will use the solar controller tied to my battery bank.

What I am finding out is this solar energy at the battery terminals when being used will only provide me smart mode charging of the 14.4VDC/13.6VDC/13,2VDC modes with a capacity of around 15-16AMPS. Based on battery science this will not be enough battery charge for my particular battery bank to get me back to a 90% charge state each day to sustain my current battery drain each day.

I am sure all of this is really going to help me but it appears if we want to run all of the things we are currently using during the one day/one night camping run off the batteries we will have to still use the generator each day when allowed by the local campground to always start off my battery bank run with a 90% charge state.

From past experience I have learned not following this 50% to 90% discharge state with my batteries they will not perform as expected and eventually will start doing damage to the batteries.

I have not done any real time use of solar panels yet but I suspect if I get enough charge back into the batteries during the day but still have to run my generator to insure I get back to the 90% SOC then the generator will still need to run three hours to attain this. I am not sure my PD9260C will know that the batteries might already be at the 70% or 80% SOC and will just run thru its normal three hour smart mode charge routine. Actually I suspect my PD9260C converter/charger will not even go into smart mode charging in auto mode if the batteries are already up to 70%/80% charge state. I will have to force the PD9260C into its 14.4 charge mode. When i do this I think it run its full three hour smart mode run.

The smaller SOLAR PANEL installs will definitely make a great trickle charge system during the ONE DAY of SUN but will have to used more long term to bring a 50% SOC battery bank back up to its 90% SOC state. i.e. you can't use any short cuts here to re-charge your battery - what you take out you have to put back...

The bigger plan would be to have a bigger battery bank than you need and then when running solar during the day it will have a place to store all of the solar it gets. The larger battery bank will not get down to its 50% SOC in a one day/one night run off of the batteries... The other solution of course is not planing on using as many 120VAC and 12VDC appliances items as before... We was wanting to stay away from candles and flashlights as much as we could - we paid those dues already from our early tent camping years from the late 50s...

My first impression on solar panels was thinking i if I installed 120WATT panels I would get a full 120WATTS of solar energy to use. The 120WATTS is based on the Dc VOLTAGE output of the panel and when you use the solar controller to get the smart mode charging voltages you need the available DC current out is reduced alot. Most 120WATTS panels have around 5-6AMPS usable DC current available.

Just some of my early thoughts here on what I may expect to gain from adding solar panels... Every situation will be unique... The ones that jump up and down saying they last for multiple days on end by adding solar panels are not using the same amount of DC power I am currently using each day/night battery run. (Unless I am missing something here). In the short term my three 120WATT added SOlar Panels will not be much help - I will still have to run my 2KW generator each day when allowed for our lifestyle of camping off the power grid... This makes me think I might be better off by using the $150 per 120WATT panel for more batteries hehe... All of this plays together for sure...

I may have a different story to tell once I have added the three 120WATT solar panels and get some real time using them off the power grid...

Roy Ken

[mena661]

gatorcq wrote:
http://www.batterystuff.com/kb/tools/solar-calculator-tutorial.html

http://forums.trailerlife.com/Index.cfm/fuseaction/thread/tid/25705772/srt/pa/pging/1/page/1.cfm

http://www.jackdanmayer.com/rv_electrical_and_solar.htm#The Golden Rules

I choose to use the quick reply, instead of inserting Links.
Everything you really wanted to know is here.

http://www.batterystuff.com/kb/tools/solar-calculator-tutorial.html

http://forums.trailerlife.com/Index.cfm/fuseaction/thread/tid/25705772/srt/pa/pging/1/page/1.cfm

http://www.jackdanmayer.com/rv_electrical_and_solar.htm#The Golden Rules

[KJINTF]

You should consider the shipping costs asssociated with the larger panels as well as the logistics of getting them up top and mounted. Check out the dimensions/weights look at UPS web site them check out the alternatives many are very pricey

Yes sure a series parallel arrangement of the panels can be used as well as a simple parallel arrangement or a total series. Too many variables to offer much more.

[gatorcq]

http://www.batterystuff.com/kb/tools/solar-calculator-tutorial.html

http://forums.trailerlife.com/Index.cfm/fuseaction/thread/tid/25705772/srt/pa/pging/1/page/1.cfm

http://www.jackdanmayer.com/rv_electrical_and_solar.htm#The Golden Rules

I choose to use the quick reply, instead of inserting Links.
Everything you really wanted to know is here.

[pianotuna]

Hi,

If using 17 volt panels it may be cheaper and better to wire them in parallel and use a pwm controller with a temperature probe to optimize charging voltage.

If you wire them in series/parallel a more expensive MPPT controller must be used.

When panels were more expensive mppt made good sense. Now they are dirt cheap the greater ability to wring watts out of the panels is not quite so important.