How much solar do I need?

[Almost There]

That too!

OTOH getting dog piss off the ground level panels was not that much fun...

 

[tripper]

400 watts of solar (roof/portable) and 200 AH of batteries will work for 1 12v fridge, led lights, small tv, low power laptop. 1 vent fan, and charging phones. Just the normal basics. This is a good combo to get by during the winter, and a lot of power for the summer. A must is a programmable MPPT solar controller, don't cheap out on a $30 PWM controller, it will cost your batteries in the end.

If you want to run an inverter and some 120V AC items you will want more batteries and solar; for items like microwave, coffee pot, charging ebike battery you will need to double the amount of solar/batteries.

You can get by on less, but you will have to watch your power consumption carefully on winter or cloudy days. 100-200 watts of solar will have a very hard time to ever get your batteries to full , and the batteries will likely die in 3 years or less.

 

[John61CT]

> small household refrigerator
The whole thing run through an inverter switched on all the time? Will waste a lot, maybe 4-10x as much as a proper 12V compressor fridge, better IMO to save up for one of those.

There are threads from those that use a 12V thermostat to cycle the inverter on/off, that saves some, but even the most efficient mains fridge uses too much IMO.

> lights
If energy efficient 12V LEDs, not much, depend on watts and how many hours per day, whether dimmed or not

> coffee maker
Totally unknown, depends on type, how long one cycle takes and how many times per day. Probably a fair bit

Would be much better to switch to propane.

> recharging a phone and laptop
This is pretty minimal, much less than the variation from weather conditions

IMO you need as much solar as fits on your roof, if that's not enough then you will have to reduce your usage or use a genny.

Or can you get overnight access to shore power every other night?

Get 200+AH batteries to start and an AH counting meter, and find out how much all this uses in AH per 24 hours. A DMM will also be helpful.

If it turns out you need more battery storage, you want to buy it quickly all the batts in a bank should match. ​The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club.

 

[vtwinkicker]

Rolling BnB Wrote:
I wish someone would just say 'I have this much solar/# of batteries/size of inverter and this is what I run on it.' I have watched so many videos and read so many articles and they just make it more confusing.

I have 300w mounted flat on the roof. They charge two 6v batteries. They easily run my 65qt dual zone Dometic fridge/freezer and Maxxair fan and LED lights. I also have a 300w pure sine inverter for the laptop and blender and I charge the usual phone/camera/batteries as needed. Going on 3 years with this system and I never had a want/need for more.

 

[tripper]

Rolling BnB Wrote:

I wish someone would just say 'I have this much solar/# of batteries/size of inverter and this is what I run on it.' I have watched so many videos and read so many articles and they just make it more confusing.

So my answer is I have 1000+ watts of solar, I run whatever I want during the daylight hours, and my batteries are fully charged by no later than 10 am. I put a much solar as I could on my roof because I did not want to worry about power ever again. Really if you have the money, put as much solar as you can on the roof, it is not that expensive if you do it yourself.  There is no downside to putting as much solar as possible.

I have 1000 watt pure sine inverter which is powered by 1 x 100 AH LiFePo4 battery ( 2 x 100 AH AGMs would work the same), and this runs a small (600 watt) microwave, 5k AC, Induction cooktop (on med power), 12v fridge, 12v television, wifi booster, cell phone booster, charges a 52v ebike battery, and charges up a power sucking gaming laptop. I also run the rv propane/120v fridge on AC during the daytime. Obviously I can only run a few of the big items at a time. The LFP battery is charged via a 3 x 305 watt house panels (tilt able) and if needed an external 160 watt portable. Basically once you get to this level of power you have everything that a house has. I just use the high power draw stuff during daylight hours.

I am sure 600 watts even just flat mounted would work just the same except for AC.

I have a secondary power system, that runs the usual RV systems, lights, fans, water pump, etc and this is powered by 1 x 105 AH Trojan  lead acid. This is powered by 260 watts of solar + 100 watts portable if needed.

I have increased my system in increments and realized that a lot of solar was the way to go as the time you want power the most is when you are stuck inside for several days in the rain watching tv or surfing the net on a laptop and you don't want to have to conserve power when stuck inside all day. I found 100 watts was NOT enough to fully charge a 100 AH lead acid battery, and 160 watts could not do it in the wintertime, meaning shortened battery life.

You might think it is wasteful having that much solar (which it isn't), but when it is raining for 3 days straight, occasionally there will be an hour of daylight here and there, with a lot of solar you can recharge your batteries fast. Heavy overcast days I still can get 150 -300 watts. Just need an agm (or LFP) battery that can take the high charge current (wet lead acid batteries cant take fast charges).

 

[Guji]

I splurged and bought a 1500 watt solar generator... I'm not living on the road yet...is anyone out there meeting their electrical needs with a solar generator?
of is this off subject?

 

[John61CT]

This thread is really about sizing the panels wattage you need, vs your daily consumption in AH.

Marketeers misuse the term "generator" to make you think what you're buying replaces the functionality of owning a noisy fossil fueled one.

Some products do actually include solar panels, for example for your description there should be 1500W of panels included with yours (unlikely)

but many are just a "powerpack", usually an overpriced low-capacity battery box with ports and some electronics that may or may not meet your needs.

The market is really full of scammers and IMO it is best to DIY.

Probably best to start a new thread to help us figure out the details of whatever it is you bought.

Or you can post to this one here: https://vanlivingforum.com/showthread.php?tid=23546

 

[JRRNeiklot]

As some of you may have noticed from my other threads, I've been agonizing over battery choices. I thought I'd list my data here and see if I could get some feedback. I need enough solar to run a 12 volt fridge, fan, charge two laptops, a phone, various other small devices (ereader, flashlight, etc), water pump (negligible, I have no shower and a tiny sink), Led lights, very rarely, a 24 inch tv (I turned my tv on about 3 times all last year). and my cpap machine. That's about all I can think of. The laptops are the only items that require an inverter.

Fan: 3.5 amps X 8 hours?
CPAP 3 amps X 8 hours
Fridge 2.5 amps X 8 hours (supposedly has a 30% duty cycle, likely more in hotter weather)
Laptop #1 (Gaming laptop, used 3-5 hours a day, at night, mostly, will need charged at least once at
night) 4.5 amps (if charging only, likely twice that if using while charging) X2 hours to charge
Laptop #2 (Media laptop, battery lasts like 4-5 hours, will likely only need charging during daylight hours.
Led lights .2 amps (will probably only run 2 at any given time, perhaps 4) X 8 hours

That comes out to about 100 amp hours, worst case scenario. How much solar do I need? I was thinking of going with a 200(ish) ah battey bank with 400 watts of solar. Now I'm thinking I may need to double the batteries. Considering my needs (and wants, I'm not giving my gaming up, if there's an internet connection nearby) what would you recommend?

Thanks.

 

[John61CT]

Given the critical CPAP and the fridge+gaming, I'm thinking 400+AH would be minimum in mostly-sunny lower latitudes, more maybe double in the cloudy north.

Solar should be as many watts as you can fit on the roof, unless you have an 8x30' rig.

A small genny with a good charger sized to fit will reduce the need for both, you may find with a small roof area solar alone just can't keep up.

Or getting to shore power overnight couple times a week, less solar is OK but still need the big bank.

Only way to accurately know your total loads' actual draw is put a Watts Up or similar on the bank with it all set up and in use for a few days, even if it's in your living room.

And the actual total harvest from solar, not until you get out there, will radically vary by location, weather and parking spot.

 

[A Savage Adventure]

I had a 90W Panel included with my Travel Trailer. The Fridge, Microwave and A/C all run off 120V (well, the fridge can do Propane as well). I have an extra battery, but after watching Bob's videos on the subject as well as a video from Carolyn's RV Life about Discount Solar in AZ, I am thinking a trip there is in order. I wish I had put more thought into my power system before I bought anything. The current charge controller is only an 8A unit and no inverter in this small RV.

 

[John61CT]

Yes the US camper industry does a p1sspoor job 99.9% of the time you're better off doing all the electric stuff yourself if planning on doing a lot of boondocking.

The market here assumes you always have grid power

 

[A Savage Adventure]

Yeah, that's the thing...I am planning on Boondocking after the 18th. Right now I am in an RV park, but that was not my long-term plan. I was buying myself some time to wrap up loose ends so I could travel and be away from here.

But anyway, I should have done it myself. I am an Electronics Engineer, but I have some health issues and so I put it off. I could have saved myself some headaches with more forethought.

 

[jrose152]

So after a bunch of research I think I am almost ready to order what I need with the help of you guys. My 2006 sienna is a part time camper van and I would like to power a 12v fridge(Dometic CF 25 or maybe a CF 35. I haven't decided yet.), a regular laptop, some led lights, a 12v fan or two, a cellphone quick charger for an android, a charger for an iphone, a nikon d90 camera battery charger, and maybe some other small things I can't think of at the moment but that is the bulk of it. Obviously they all won't be running at the same time but the fridge will be plugged in all the time.

My question is how many watts should I put on my roof? I was thinking 2 100w panels from Renogy. Also I'd like some recommendations on what 6v golf cart batteries to buy(get two to make 12v) as well. I would ideally like 2days of power in rain/shady camping spots but 3 days would be ideal. Any links or suggestions would be greatly appreciated as I'm having trouble figuring out how many watts and how many amp hours in batteries to get. I'm not on a shoe string budget because I've been saving for solar for a while now but I also don't want to shell out more then I need to. I just want to do it right the first time. As far as the specific charge controller I will worry about that when I figure this out unless there are suggestions for that as well. I plan on doing everything DC.

 

[highdesertranger]

jrose, 200 watts of solar would be the minimum for two 6v batteries. not sure how much room you have on a Sienna roof but 300-400 would get you a little more breathing room for cloudy days. highdesertranger

 

[jrose152]

*deleted*

 

[jrose152]

jrose,  200 watts of solar would be the minimum for two 6v batteries.  not sure how much room you have on a Sienna roof but  300-400 would get you a little more breathing room for cloudy days.  highdesertranger

My roof rack is measured roughly 42x60. 42 in the width is the inside edge to inside edge from side to side. Originally I was going to try to fit the panels in between them instead of onto so it was a little more sleek looking. Would the two batteries give me 3 days of power? Granted I won't be living inside of it as it is a camper for road trips and weekend camping trips right now. I could fit a 300w renogy panel up there but they don't sell them where you can just get one and shipping would be really expensive. I figured 2 100w panels would do the job as the only daily items would be charging my phone and the fridge needing to run. The other things would be occasional. Maybe I'm going about building my setup incorrectly for what I want to do? I'm mostly worried about the fridge as the other stuff would be occasional.

edit: The wiki says "200W is not a magic number, but it is the most common size of solar install for vandwellers and boondockers. It is probably more than what's needed for the basics and has enough power to add in a 12v compressor refrigerator if desired.8)"

 

[Spaceman Spiff]

 . . . I would like to power a 12v fridge(Dometic CF 25 or maybe a CF 35. I haven't decided yet.), a regular laptop, some led lights, a 12v fan or two, a cellphone quick charger for an android, a charger for an iphone, a nikon d90 camera battery charger, and maybe some other small things I can't think of at the moment but that is the bulk of it . . . 
My question is how many watts should I put on my roof? I was thinking 2 100w panels from Renogy. Also I'd like some recommendations on what 6v golf cart batteries to buy(get two to make 12v) as well . . .

I have two 100W Renogy panels and two GC2 6 volt batteries at 208AH.  I run a refrigerator, MaxxFan, MacBook ~ 2 hours a day, cell booster, LED lights, and a couple of 12V fans plus charge an iPhone, inReach SE and camera occasionally.   I am almost always at 100% before dusk.  I can go 2 days without sun to 60% and have to find charging.

Best price I found was at Sam's Club 4 years ago for GC2 @ $87 each.

 

[jrose152]

I have two 100W Renogy panels and two GC2 6 volt batteries at 208AH.  I run a refrigerator, MaxxFan, MacBook ~ 2 hours a day, cell booster, LED lights, and a couple of 12V fans plus charge an iPhone, inReach SE and camera occasionally.   I am almost always at 100% before dusk.  I can go 2 days without sun to 60% and have to find charging.

Best price I found was at Sam's Club 4 years ago for GC2 @ $87 each.

Awesome, this seems to be a similar setup to what is like to run and it seems 200w with 2 batteries should do me fine. I'd there anything you would have done differently if you could do it again?

 

[John61CT]

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club.

As much solar watts as you can fit on your roof would be ideal

200W will only be enough to run a fridge ++ in constantly sunny conditions, or if you have other charge sources.

Getting batts back to 100% Full at least a few times a week is important for longevity.

 

[jrose152]

The best battery value by far is Duracell (actually Deka/East Penn) FLA deep cycle golf cart batteries, 2x6V, around $200 per 200+AH pair from BatteriesPlus or Sam's Club.

As much solar watts as you can fit on your roof would be ideal

200W will only be enough to run a fridge ++ in constantly sunny conditions, or if you have other charge sources.

Getting batts back to 100% Full at least a few times a week is important for longevity.

Since this is a weekend dweller for camping and road trips, I could always unplug the fridge when not in use.