mom wants solar on her class C.... i need to do this cheap.

[bigcitypopo]

Hi all,

trying to help my mom out... she has a brand new 2014 coachmen ... its a 27' class C on a E450 Chassis V-10

i found these.. 18' flex panels... for $99 ea.
!!! Sun electric has them for $76!!!
I was thinking two... now i need an MPPT controller to use to change the voltage to 12v... my question is... what is the true wattage convert when charging at 12v, or is it charging at a higher amp rating... a little confused I be.... and i haven't even started the Cider yet.. lol

whats a good true MPPT controller to use...

[BFL13]

I hope you are looking at inverters for dear old Mum! She can at least watch television that way. With a little more effort, she can even run the microwave when not on shore power.

[bigcitypopo]

PT... i wired them properly after she bought the rig.. as they weren't balanced... her batts ive in the step inside the rig. the lid lifts (its sealed) vented outside... If i were to add extra batts I'd have to use a torklift jobber that goes on the frame....

[pianotuna]

Hi,

No need to swap the batteries until the existing ones do not meet her needs. You may find that what she has, if wired in a balanced manner will last a lot longer once solar is caring for them.

[bigcitypopo]

the cool thing: 6feet of cable to the batteries!

I think i'm gonna grab the 280wkit from solarblvd... and have her setup for a third panel if she needs it.

I'm gonna swap the batts for 6V's too... this is her "granny flat" lol... and emergency/disaster/zombie bugout vehicle. 🙂

[eb145]

bigcitypopo wrote:
We (I) have geared her whole rig around 12V living... I ran an anmeter and she drew 68AH over a 2 day period... Just fridge, some LED lights and 12v TV.. I think I want to set her up with 3 of those 140w panels....

It sounds like you are on the right track. I would suggest also 2 things:

1. install the charge controller as close to the batteries as possible to minimize voltage drop between them (unless the controller includes remote voltage sensing). This will allow faster charging.

2. try to get a charge controller with temperature compensation. My low-cost PWM controller has it. Colder batteries need to be charged at higher voltages - having the charge controller adjust voltage with temperature automatically is real nice.

Ed

[AllegroD]

How does your mother use her MH? What applainces (large, med & small) does she use?

[ewarnerusa]

rtate wrote:

Salvo wrote:
I would avoid mppt if you want to do it cheap.

Get two 12V, 140W panels for $160. The pwm controller costs about $30.

https://www.solarblvd.com/product_info.php?cPath=1_269&products_id=2668

I really dont understand much about solar charging or electricity for that matter.
Would that mean that theoretically these panels would be capable of putting 23.3 amp hours into my batteries? 2×140 watts÷12 volts =23.3 amps.

As a practical matter how many amp hours could you expect to add to your battery bank on an average day?

I run two of these Cynergy 140 watt panels with a Morningstar Tristar 45 controller. Mine are mounted fixed and flat on the TT roof, although each are at slightly different angles from parallel to the ground based on the curved shape of the roof. On a bright sunny day during bulk charging I can see the claimed max amps for a total of 15-16 amps.

When I started I was strictly 12V as well. Then I realized that I'm harvesting free power from the sky and I ended up with an inverter and a fixation on what 120V AC gadgets I can also run. So despite the initial intentions, things may change once you realize what you have available.

[pianotuna]

Hi Niner,

I can't read the future. I can say that where I live we get down to 8 hours of visible light in the winter. That alone suggests lots of solar wattage. The side effect is that the system costs perhaps $140 extra now, and that a flat fixed install will work well in almost all conditions.

[NinerBikes]

pianotuna wrote:
Hi,

I would go with the 3 panels. No telling if "Mom" will want to add an inverter in the future, and if she does consumption will be much greater. There is no such thing as too much solar, especially during the short winter days.

For example, one hour of a 300 watt inverter would consume as much as all the current parasitic loads.

Reread, he's got her all on 12V system, meaning an inverter might not be in her future.

[2oldman]

NinerBikes wrote:
A wealthy lady that's always hooked up... hmmm, where do I find her? You need to introduce me. 😉

Will do!

[pianotuna]

Hi,

I would go with the 3 panels. No telling if "Mom" will want to add an inverter in the future, and if she does consumption will be much greater. There is no such thing as too much solar, especially during the short winter days.

For example, one hour of a 300 watt inverter would consume as much as all the current parasitic loads.

[NinerBikes]

2oldman wrote:

rockylarson wrote:
It is not uncommon for a laypersons expectations of a solar installation to far exceed practical limitations.

Yes, or even need solar in the first place.

You don't want to put solar on only to have her staying in RV parks all the time. The cheapest, by far, is to not do it at all.

A wealthy lady I know put 4 of the most expensive AGM batteries in her coach, and she's always hooked up. Someone convinced her she needed them. One, maybe.

Is there such a thing as battery status bragging rights, like the marquee on your trailer or your tow vehicle?

A wealthy lady that's always hooked up... hmmm, where do I find her? You need to introduce me. 😉

[2oldman]

rockylarson wrote:
It is not uncommon for a laypersons expectations of a solar installation to far exceed practical limitations.

Yes, or even need solar in the first place. You don't want to put solar on only to have her staying in RV parks all the time. The cheapest, by far, is to not do it at all.

A wealthy lady I know put 4 of the most expensive AGM batteries in her coach, and she's always hooked up. Someone convinced her she needed them. One, maybe.

[NinerBikes]

bigcitypopo wrote:
We (I) have geared her whole rig around 12V living... I ran an anmeter and she drew 68AH over a 2 day period... Just fridge, some LED lights and 12v TV.. I think I want to set her up with 3 of those 140w panels....

68 amps over a 2 day period is 34 amp hours a day. Two 140W panels will be more than enough. Was this measured in the summer or the winter, when the nights are longer? You'd probably have her do fine with two 100 watt or 120 watt panels, with her usage level.

I go through 35-45 amps a day, and I am using a 150W panel... 8.4 amp peak charge rate, and an adjustable voltage charge controller, set at 15.0V daily. I find it easier to keep batteries in tip top shape with that voltage setting when camping. I disconnect the battery completely when trailer is in the storage yard and top charge battery before putting away in storage, and then top off battery with distilled water as necessary after charging up for storage.

I am running a true commercial grade deep cycle battery, no calcium in solution in the plates, antimony instead and thick, thick lead plates. About 90# worth of battery for 150 amp hours. All those little things add up, if you are a purist, or an electrical engineer, or an electronics geek.

For small scale 12V stuff at 240 watts or less, I prefer portable solar panel set ups over fixed,mounted on the roof. Far more harvest and efficiency any time of year if you aim them and chase the sun a little bit. Means also owning less panels and less up front cost,because so much more efficient when portable, higher yield in amp hours per panel.

If I sell my travel trailer and upgrade, my portable solar panel comes with me, not lost in the sale to someone who may not care to use solar in the first place.