Just another question on Solar

[huron52]

I have read a lot of threads on solar installs and I have a question or two.

I am thinking of adding solar to my toy hauler. Planning on about 500watts. Also planning on two 6 volt batteries to start then adding another two 6 volt batteries to the mix.

I am not interested in running my air conditioner but might want to have 120 volts to maybe watch TV or something like that.

So, correct me if my thought process is wrong here.

I plan to install solar on the roof, line down to switch then to controller and then to battery bank.
Controller not installed in with the batteries.
Then connected to the batteries, separate line off to a inverter away from batteries to get 120 volts in the cabin area.

I have dry camped for long weekends with just the batteries so 120 volts is not a biggy at this time

[time2roll]

einstein2nd wrote:

2oldman wrote:

einstein2nd wrote:
Limit TV after the sun goes down: No Sun, No Power.

What are the batteries for?

Listen, if you can't figure that out... go to school!

Read what "KJINTF" said about batteries.

KJINTF wrote:
It will easily keep two 6Vdc batteries charged up if you have the sunshine
and not too many other loads

I think KJINTF just said to limit power to get the battery charged.
Then einstein2nd says to get the tv on during the daylight and off at night.

So which is it? 😉

[time2roll]

OP is good to go so back to the fun :B

[einstein2nd]

CA Traveler wrote:
einstein,

The typical modern panel has bypass diodes so shading is a non issue. RVers with smaller arrays than yours would be better served with fuses vs a 0.5V drop diode since the typical solar controller provides night time blocking.

I agree on small systems like 2 or 4 panels in parallel the bypass diodes will suffice.

When you increase the voltage by series is when you start to go beyond the bypass diodes' rated power. Therefore, adding an additional diode rated for the full string will isolate each string of panels from the others.

Diodes not only help with shading but also helps with: improper installation, isolates manufacturers' defects, and isolates damaged panels from the others.

Example (more like a what if):

Two panel system in parallel: One panel is damage and water sets in and shorts out internal wires. The damaged panel acts like a load and draws from the other panel which will burn out if not protected.

If you isolate with a diode the power will never divert to the short and you get at least half of the power to your controller. If you use fuses the fuse pops on both panels and no power goes through. Diodes are as cheap as fuses now days.

Note: circuit breakers can be reset, but after it trips/pops, it is recommended to be replaced according to the manufacture. Just a tidbit :-).

Edit: Fuse works if you want to know if something is wrong. Diode works if you just want outputs no matter what.

[CA_Traveler]

einstein,

The typical modern panel has bypass diodes so shading is a non issue. RVers with smaller arrays than yours would be better served with fuses vs a 0.5V drop diode since the typical solar controller provides night time blocking.

[jrnymn7]

yep.

[2oldman]

And now back to the OP.

[einstein2nd]

2oldman wrote:
There's no entertainment like this place.

They say misery likes company. They try to bring others into the darkness with them; blaming them for their sorrows.

You need to find a better hobby! With a rig like yours you should be enjoying the open roads instead instigating fights on a forum which probably helped you with your 800watt system. Or you are bitter that you hired a tech to install yours after realizing the information was always at your fingertips.

[2oldman]

There's no entertainment like this place.

[einstein2nd]

2oldman wrote:

einstein2nd wrote:
Limit TV after the sun goes down: No Sun, No Power.

What are the batteries for?

Listen, if you can't figure that out... go to school!

Read what "KJINTF" said about batteries.

[2oldman]

einstein2nd wrote:
Limit TV after the sun goes down: No Sun, No Power.

What are the batteries for?

[KJINTF]

Sounds like you are on track to enjoy noise free solar power
500watts is good - next step choosing the panels, controller, wires, connectors, switches, fuses, etc....
It will easily keep two 6Vdc batteries charged up if you have the sunshine
and not too many other loads

Modern HDTV's LED/LCD TV's in a RV should draw no more than 75watts (or about 6amps at 12Vdc) for any TV sized 19">32"

Two GC Batteries with 220amp/hr - at 50% discharge you should be good for 100amp/hrs of evening / night time use when fully charged up - Over 10hrs of TV

A reference point my 19" CCFL/LCD draws about 36watts or 3amps DC

[einstein2nd]

CA Traveler wrote:
If you have more than 2 panels in parallel they should be individually fused. Add a fuse or better yet a switchable CB between the controller and battery.

For panel placement minimize shadows from the rig.

Any panel in parallel requires to be isolated using diodes and circuit breakers/fuses.

Example: I have 24 panels connected. 6 rows of 4 panels in series. Each row has a diode rated for maximum power. This will minimize the other panels from using the shaded panel as a load. In addition, each panel has two or three diodes to isolate between series. Each row will have a circuit breaker/fuse.

[einstein2nd]

2oldman wrote:

einstein2nd wrote:
Modern TV's use about 250watts leaving 250watts to charge batteries.Just remember once the sun goes down limit TV use.

Einstein? Hmmm. What 'modern' TV uses 250w? Why limit TV to be 'run' on solar? What 500w system puts out 500w watts?

Modern TV: Phillips 32" HD LCD TV uses 125 watts.
Limit TV after the sun goes down: No Sun, No Power.
Outputs: I didn't feel like stating the reduce rated power. A 500w system will generator at least 60% of the rated power: 300watts if the efficiency is below 13%. So technically my tv will use: 125watts allowing 175watts to the house batteries. I live in the deserts where we get a lot of sun. So if you live in a cloudy area the output will be reduced.

[2oldman]

einstein2nd wrote:
Modern TV's use about 250watts leaving 250watts to charge batteries.Just remember once the sun goes down limit TV use.

Einstein? Hmmm. What 'modern' TV uses 250w? Why limit TV to be 'run' on solar? What 500w system puts out 500w watts?

[CA_Traveler]

If you have more than 2 panels in parallel they should be individually fused. Add a fuse or better yet a switchable CB between the controller and battery.

For panel placement minimize shadows from the rig.