Solar.... ? on usage during day/night. solar add on

We have a GoPower 150 watts on roof, controller and 600 watt inverter system. Works great... never use generator, unless we want to watch tv.... except this past south trip....

We have 2 6 volt batteries...

My question is I know you have the solar on roof and you charge all day, if sun. And you use all day, see the charge go from 12.5 to 14.0 and varies all day... and then you use power and it goes down...

My question is... IF you added another solar panel, would you charge batteries faster and keep them at a full charge more? Especially if you used tv, direct tv receiver and dome for an hour during day, which uses power...

Thinking of adding a portable solar panel to system to keep batteries FULLY charged and not going down during use of water pump, fridge, etc.. during day...

Waste?? as batteries will only accept so much .??????????????

Are the 224V AGM batteries really that much more volts to use with our 150 watt solar....

thanks...... just don't understand the usage during the day vs the charging................ make sense??

My situation is similar.  We don't have solar yet but are thinking of a portable system.  Probably 100 watts.  I'm curious about your usage.  Unless you have a residential refrigerator, I'm not sure how just watching TV via your inverter would run your batteries down when you have a 150 watt panel on the roof.  Are you running other appliances, lights, etc.? 

The short answer is yes, to a point adding additional panel(s) will provide quicker charging via additional amps being supplied to the battery.  The long answer, it is important to size a solar system appropriately with respects to the number of batteries you have.  Understand the solar panels are not powering your energy requirements, rather it is the batteries role to do that.  The solar pannels and charge controller simply replace consumed amps.  A good guideline and starting point is to have 1 watt of solar for each amp of battery capacity, so in your case you say you have 2-6V batteries, but did not indicate the amp hours, so I will hazard a guess of approximately 180 - 225 amp hours.  For argument sake, call it 200 amp hours which would equate to a 200 watt solar array.  This for a recreational RVer with a mixture of RV park and some boon docking would be appropriate.  For a frequent boondocker or a full-timer a 1.5 to 2 watt of solar for each amp hour of battery capacity, would account for heavier use and the need to charge the batteries  quicker. 

Hello, thanks, not sure on amps on the batteries, I will have to look, but not agm batteries.

We currently have 150 watts on the roof and for us that is basically fine. We don't run anything "hot" hair dryer, microwave, etc. and that is fine with me. It charges our batteries in the yard while sitting and on our 63 night trip that was a mix of electric hookups and dry camping. We did a 17 day stretch of dry... and had plenty of battery power.

We would like to possibly run the TV a little on our solar and met a guy who had 180 watts of solar, a couple of cig. lighter to outlet chargers and watched his TV and movies. That being said I don't want to add a bunch just for TV. We are fine without microwave... my inverter charges laptop.

Just considering the additional panel to possibly "boost" the system when we are maybe doing some extra.... maybe want to make sure we have a good charge for nighttime to run furnace more in our cold Montana weather...  and not sure if panel is the way to go or maybe to do two 6V AGM batteries...

thoughts.

But we love our solar! even minimum as it is... so nice to go out and get ready for camping and not have to watch our batteries.. Our solar takes care of them... 

PS... the generator is IN the truck... always!!! only used one time for emergency... but that was not because of battery power, we lost propane regulator! and needed to run for fridge!

To size RV solar efficiently, it helps to have an understanding of your consumption, Ah capacity and your needs. Having said that, it sounds like you're electrical needs are pretty well balanced right now.

If you were to add another 100 watt solar panel, your house batteries would probably get fully recharged a little earlier in the day (depends on a few factors) and they'd likely remain fully charged later in the day - especially if you switched to an MPPT controller. You almost certainly have a PWM controller now. That would mean that, given good sunlight, you could watch more TV and still get your batteries up to full charge. With flooded cell batteries, that's important.

The batteries you mentioned are actually 6 volt batteries with a 220 Ah capacity. If you're considering them, you'd need to get two for your 12 volt system. I don't know what your current battery's Ah capacity is, but if it's significantly less than 220 Ah, and you switch to the 6 volt batteries, you will likely "need" to get more solar to fully recharge those batteries, or use your generator.

Kev

tanglemoose said:

Hello, thanks, not sure on amps on the batteries, I will have to look, but not agm batteries.

We currently have 150 watts on the roof and for us that is basically fine. We don't run anything "hot" hair dryer, microwave, etc. and that is fine with me. It charges our batteries in the yard while sitting and on our 63 night trip that was a mix of electric hookups and dry camping. We did a 17 day stretch of dry... and had plenty of battery power.

We would like to possibly run the TV a little on our solar and met a guy who had 180 watts of solar, a couple of cig. lighter to outlet chargers and watched his TV and movies. That being said I don't want to add a bunch just for TV. We are fine without microwave... my inverter charges laptop.

Just considering the additional panel to possibly "boost" the system when we are maybe doing some extra.... maybe want to make sure we have a good charge for nighttime to run furnace more in our cold Montana weather...  and not sure if panel is the way to go or maybe to do two 6V AGM batteries...

thoughts.

But we love our solar! even minimum as it is... so nice to go out and get ready for camping and not have to watch our batteries.. Our solar takes care of them... 

PS... the generator is IN the truck... always!!! only used one time for emergency... but that was not because of battery power, we lost propane regulator! and needed to run for fridge!

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17 continuous days of dry camping.  You did really well with your setup, and as you wrote you don't use a lot of power.

If you are going to continue dry camping/boondocking for more than 2-3 days between hooking up to shore power, you really need (must) install a good battery monitor such as Trimetric:  http://www.bogartengineering.com/products/trimetrics.html

The monitor adds a "shunt" between the negative terminal of your battery pack and all the negative wires which go to your house batteries.  From the shunt you run a 4 wire light weight cable up to the inside of your RV to mount the remote display.  The cable, directions and the remote comes in a package.

What the monitor does is monitor and display the total of the AH (Amp Hours) going out and back in your batteries.  It also displays the current number of amps going in or out of the batteries, and the battery voltage.  By displaying the AH's used you will know the true state of the charge (SOC) of your battery. 

For example a pair of 6V golf cart batteries wired in series for a 12V battery pack gives you a total battery capacity of about 220AH.  Only about 110AH is usable, i.e. 50% of the total capacity.  Using more than 50% greatly reduces the life of your battery pack.  BTW, for longest battery life only use 25% of the capacity.  That is keeping the battery 70%-75% full. 

Knowing the SOC of your batteries allows you to determine how long you can watch TV and/or operate other devices. 

Also with the instant amps display showing the amps going out of the batteries, you can turn on the satellite RV receiver and TV and truly know how long you can watch TV before you run the batteries down to far.  Or know you shouldn't run the RV because you have a cold night coming up and you need to run the furnace.

I have about 195W on the roof, 2x6V golf carts and a Victron battery monitor.  This systems works very well for us.  Even in colder weather with the furnace running all night we get back to full charge by 2-3pm in full sun.

The reason I'm seriously considering adding another 175W is because we don't always have full sun.  Either tree's or clouds.  Haven't needed it yet, but I tend to over-do things to sleep better

Having overcapacity with solar panels is most noticeable when it is overcast outside.  I can still get 8 amps on a very cloudy day but that is better than nothing.

Are you saying this 8s a good time to have extra solar panels?

Drewd said:

Having overcapacity with solar panels is most noticeable when it is overcast outside.  I can still get 8 amps on a very cloudy day but that is better than nothing.

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tanglemoose said:

Are you saying this 8s a good time to have extra solar panels?

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If you do quite a bit of dry camping or boondocking you can't have too much solar! 

Of course there is the additional problem that some solar installers use too small wire size from the solar panels to the controller and/or the controller to the batteries so people don't get full power into the batteries. 

Drewd said:

Having overcapacity with solar panels is most noticeable when it is overcast outside.  I can still get 8 amps on a very cloudy day but that is better than nothing.

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This is the really nice thing about solar, it is always supplying power even with some clouds.  8 amps on a cloudy day means getting 32-40AH (Amp Hours) back in the batteries during the peak 4-5 hours of daylight.  But in addition you will start getting 1-4 amps in the earlier and later daylight hours.  These hours of charging add up.

I am always amused by the "experts" that only talk about the power you get from the solar panels during the 4-6 hours of peak sunlight and totally ignore the extra 25%-30% of the total daily power you get in the earlier morning or later afternoon to early evening hours.  It king of like "you don't get any amps from the solar until 10am and then by 2-3pm you get nothing from the solar panels.

Now I don't necessarily positive amps going into my batteries during these early or late hours.  What I do see is the reduction in the amps going out of the batteries.

AND this these amps coming from my solar panels happens without my having to DO ANYTHING.  I don't have to think about it, I don't have to remember to turn something on.  It just happens automatically.

What Al just said X2. If you boondock a lot, you can't have too much solar.

Kev

tanglemoose said:

... the generator is IN the truck... always!!!

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Just a point to ponder, your truck already *is* a generator.  When I was using a popup and before that tents, I charged my batteries by running my vehicle a half hour or whatever a day to give them a boost if needed.  Solar is nice when it works but if you're stuck in the camper or a tent on a rainy day, it's nice to have that backup and while a separate genset checks the box, I've never needed anything more charge capacity than what was already in the car/truck.  Nothing extra to bring along, nothing for someone to steal, no gas to mess with.  Not to mention quiet, an idling car is quieter than any inverter genset I've seen.  Not the most fuel efficient option but has a high convenience factor.

Mark B.
Albuquerque, NM

AStravelers said:

I am always amused by the "experts" that only talk about the power you get from the solar panels during the 4-6 hours of peak sunlight and totally ignore the extra 25%-30% of the total daily power you get in the earlier morning or later afternoon to early evening hours.  It king of like "you don't get any amps from the solar until 10am and then by 2-3pm you get nothing from the solar panels.

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well i'm glad we keep you happy... !

you will appreciate of course that DIY RV and professional off grid solar are two very different animals..
as a system designer i can assure you there are many reasons we design for solar max insolation or "sun hours"
and ignore the other 25-30%..

solarman said:

well i'm glad we keep you happy... !

you will appreciate of course that DIY RV and professional off grid solar are two very different animals..
as a system designer i can assure you there are many reasons we design for solar max insolation or "sun hours"
and ignore the other 25-30%..

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I'm sorry, I wasn't intending to step on an experts toes. 

I also didn't realize that I recommended that folks design their system for the non-max sun hours.  I mainly figured the shoulder hours and a very nice bonus which should not be ignored.  We also should not ignore the amps we get even with some cloudiness or a rainy day.

Every little bit counts in an RV.  In a commercial installation I guess that is different.

AStravelers said:

I'm sorry, I wasn't intending to step on an experts toes. 

I also didn't realize that I recommended that folks design their system for the non-max sun hours.  I mainly figured the shoulder hours and a very nice bonus which should not be ignored.  We also should not ignore the amps we get even with some cloudiness or a rainy day.

Every little bit counts in an RV.  In a commercial installation I guess that is different.

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true, you will get additional power as a "bonus", how much of course is not easily quantifiable due to the panel's optical
properties, panel location and atmospheric conditions..
therefore by designing to known insolation levels we can more accurately size our system to meet defined goals.

anyway, it's all fun stuff.. so no need to apologize..

My solar panel overcapacity allows me not to have to climb the roof and tilt the panels.  I decided early on that I dislike tilting the panels manually.

I know what you mean.

Kev

Drewd said:

My solar panel overcapacity allows me not to have to climb the roof and tilt the panels.  I decided early on that I dislike tilting the panels manually.

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Yeah, same here. I over built my solar array as well, but I am sure glad that I did!

based on my very elementary research and zero experience.... and I could have this wrong, but I saw something on youtube that lead me to believe...and Kevin touched on this earlier....
that you need to have a MPPT controller to take advantage of the added panels.  With PWM controllers the advantage of "over capacity" extra panels is slight or negligible as I understood it.
Solar experts...was there something about connecting the panels in series to gain benefit of the  MPPT controller?  increasing the voltage going into the controller?