100 Watt Solar

[Evirk]

We have a Casita 17 Spirit Deluxe with a standard Walmart deep cycle marine battery. Will a suitcase100 watt solar panel support the load of gas operation fridge, co detector and frugal use of lights and max fan? Everyone seems to favor 200 watt but wondered since the smaller unit is lighter and takes up less space.

[John in Michigan]

Supply side:

With maximum direct sunshine (ideal conditions) a 100 watt panel will provide 40 or so amp hours per 24 hour period, depending on the rating of your particular panel and solar charge controller.

Load side:

Again depends on your particular equipment. If you are using LED bulbs, the current draw is very small. Also the CO detector draw is very small. Charging phones, tablets, etc can be a significantly higher draw, but you didn't mention doing this. The max fan will draw up to 3 amps on HI. If you only use the max fan 8 hours per day, and run it on LO, may only draw 1.5 amps (?), so that would total 12 amp hours per day. Apparently a propane fridge can draw .5 amp 24 hours per day, so that's another 12 amp hours per day.

So the total power draw would be 24 amp hours or so per day. Based on that, the 100 watt panel might work depending on availability of sunshine.

[Raspy]

The gas fridge uses very little power and the co detector probably even less. If you are using LED lights frugally, that is also not much power. The max fan will be a bit more.

I'd say the 100 watt suitcase would serve you well for the loads you now have. But one thing likely to happen is that you may begin to add more loads because you can, such as charging a phone or two, a computer, or watching a movie sometimes, or some other thing.

The 100 watt suitcase is a very nice setup that will produce a surprising amount of power and is small enough to stow in a small place. Get one with an MPPT charge controller. You might even find a monocrystalline one that is the same size as a 100 watt, but puts out 120 watts.

You don't say what size the battery is, but a group 27 will store more power than a group 24. Either one should only be counted on to provide 1/2 of their rating. A 100 amp hour battery should not be expected to provide more than 50 amp hours, so factor that in. The bigger battery could help you get through a bad weather day with limited solar.

So if you think you may want to run more things in the future, get the bigger one, if not, the 100 watt should be fine. I sort of go by the idea that usage will rise to meet supply. My trailer came with 300 watts of solar and we had so much power that I started using an electric coffee maker in the mornings!

[ssatkinson]

We had a Renogy suitcase solar, 100w, with our Casita SD. It provided enough for us to use LED lights, run the furnace sparingly at night, and charge our phones during the day. We had 3 lengths of cable to adjust for each campsite’s sun pattern. Ours was a 2004 so the frig didn’t draw for the control panel as all was manual. We always had plenty of power for our minimal use even on cloudy days. We had a Group 27 battery, tight fit in the battery box but more power.

[Spongelander]

We have a thin, flexible Renogy 100W foldable panel with 20' of 10AWG cable. This has almost always proven to be enough to keep up with a load similar to that you have described. Any Fantastic Fan or furnace use will be the biggest draw.

[Evirk]

Thanks to John, Raspy, ssatkinson and anyone I may have missed. Your answers were clear and right on point. Based upon these responses I have purchased a 100 Watt Renology unit. I did confirm with Renology that the controller will allow expansion to 200 W if necessary. I'm gonna gamble this will work, and if not, I'll get the additional panel. So, taking the risk to save money and space, accepting the risk that it will end up more expensive and take up even more space.

Again, thanks to all!

[Jon Vermilye]

Originally Posted by John in Michigan

Supply side:

With maximum direct sunshine (ideal conditions) a 100 watt panel will provide 40 or so amp hours per 24 hour period, depending on the rating of your particular panel and solar charge controller.

Load side:

Again depends on your particular equipment. If you are using LED bulbs, the current draw is very small. Also the CO detector draw is very small. Charging phones, tablets, etc can be a significantly higher draw, but you didn't mention doing this. The max fan will draw up to 3 amps on HI. If you only use the max fan 8 hours per day, and run it on LO, may only draw 1.5 amps (?), so that would total 12 amp hours per day. Apparently a propane fridge can draw .5 amp 24 hours per day, so that's another 12 amp hours per day.

So the total power draw would be 24 amp hours or so per day. Based on that, the 100 watt panel might work depending on availability of sunshine.

To give you an idea of the results of a bad day, I have 320 watts of panels on the roof of my trailer and spent the day in an open field with 91% cloud cover. Collected 31.5 amp hours for the day.

[John in Santa Cruz]

i was able to dry camp indefinitely with my casita and a renogy 100w solar suitcase. in the evening, I'd aim it at the general direction of the morning sun, and by the time I woke up (often 11am or later, after an all nighter doing astronomy), my batt would be fully charged. our new trailer is an escape 21 footer, it has dual golf cart batteries (220AH at 12V total), and 160W rooftop solar, and same thing, by the time I wake up, everything is fully charged.

[jwcolby123]

What no one is telling you is that a lead acid battery does not appreciate being left partially charged. Even so called "deep discharge" lead acid batteries need to be fully charged often, preferably daily. Doing so pulls the sulfur accumulating on the plates back into suspension in the acid water. Not doing so will over time cause the sulfur on the plates to harden and the battery will slowly stop charging all the way. Sadly the damage done is gradual over time, and 6 months or a year later your battery "won't hold a charge" and you have unintentionally killed it.

Thus the advise "Charge fully every day".

It is not a trivial task to discover state of charge in any battery because reading the voltage is unreliable as a SOC indicator. In general, if you want to read the voltage as a charge indicator you need to do so after "resting" the battery, i.e no charge or discharge for some time period, at least an hour. Early in the morning before using the battery is a good time.

IIWM, I'd go get another 100 watts of solar panel. While there is no such thing as too much power, there definitely is such a thing as too little, and particularly so with a lead acid battery.

[Perryb67]

Originally Posted by jwcolby123

What no one is telling you is that a lead acid battery does not appreciate being left partially charged. Even so called "deep discharge" lead acid batteries need to be fully charged often, preferably daily. Doing so pulls the sulfur accumulating on the plates back into suspension in the acid water. Not doing so will over time cause the sulfur on the plates to harden and the battery will slowly stop charging all the way. Sadly the damage done is gradual over time, and 6 months or a year later your battery "won't hold a charge" and you have unintentionally killed it.

Thus the advise "Charge fully every day".

It is not a trivial task to discover state of charge in any battery because reading the voltage is unreliable as a SOC indicator. In general, if you want to read the voltage as a charge indicator you need to do so after "resting" the battery, i.e no charge or discharge for some time period, at least an hour. Early in the morning before using the battery is a good time.

IIWM, I'd go get another 100 watts of solar panel. While there is no such thing as too much power, there definitely is such a thing as too little, and particularly so with a lead acid battery.

There are a lot of people who have no problems with lead acid batteries. You make it out to be much larger than it really is.

I look at lithium batteries to be interim, much like compact florescent light bulbs.

If one doesn't want a battery with an internal BMS then their choice is to be the battery's BMS. Just because lead acid didn't work for you doesn't mean it won't work for others.

Enjoy,

Perry

[Perryb67]

Originally Posted by Evirk

We have a Casita 17 Spirit Deluxe with a standard Walmart deep cycle marine battery. Will a suitcase100 watt solar panel support the load of gas operation fridge, co detector and frugal use of lights and max fan? Everyone seems to favor 200 watt but wondered since the smaller unit is lighter and takes up less space.

A 100 watt portable is/can be as effective as a fixed 200 watt panel. Our 100 Renogy (not Renology) is very effective for charging a battery with use similar to yours. A fixed panel is stuck in one direction and angle all day. A portable can be set at a superior angle and moved with the sun, giving you that 200 watt equivalent. As long as your needs stay as you state you've made a good choice.

Enjoy,

Perry

[Glenn Baglo]

For the camping that I do, my two 40 watt portable panels and Trojan 27TMX battery are sufficient. Or, they have been sufficient. They were enough for my LED lights, Maxxfan, furnace fan, charging Mac and iPhones, bluetooth speakers. Looks like I'll have to plug in now that I have a CPAP and an oxygen concentrator.

[jwcolby123]

Originally Posted by Perryb67

There are a lot of people who have no problems with lead acid batteries. You make it out to be much larger than it really is.

I look at lithium batteries to be interim, much like compact florescent light bulbs.

If one doesn't want a battery with an internal BMS then their choice is to be the battery's BMS. Just because lead acid didn't work for you doesn't mean it won't work for others.

Enjoy,

Perry

I never mentioned Lithium. To say "100w works for me" only means it works for you. I think given his usage he may or may not reliably charge fully back up which is a recipe for killing his battery.

Where is he camping? Arizona desert? In the monsoon season? Somewhere where there is cloud cover a lot? Or plugged in every night? PWM or MPPT? From my read that controller is PWM. I have no idea whether the panel provides 100w around the PWM controller. Maybe so.

It sure seems no one is asking the right questions.

Look, a PbA battery requires a bulk cycle, then an absorption cycle. My understanding is that the bulk cycle is about 80%, then 20% is at a slower rate of charge. Which is why it is important to have a somewhat large current during bulk because it gets through that bulk phase fairly fast. You can claim 5 or 6 amps from the panel if you want, but if the battery is only accepting 4 or 3 or 2 amps over many hours, and you only have 6 or 7 hours of solar, then? And if it's cloudy then you might only be getting 3 amps for the bulk phase to begin with, so you never even get to the absorption phase.

I personally don't care who does what, I just object to inaccurate information and "it works for me" kind of stuff. People kill lead acid batteries every day because they don't understand how they work. Let's try to provide accurate and complete information so that people can keep their batteries healthy.

[thrifty bill]

I can only say a 100W suitcase is more than adequate for my needs, on either of my trailers. Now I did convert ALL the interior lighting on my Trillium to LED, using modern LED fixtures. Do you have ALL LED lighting? Incandescent bulbs draw a lot, LED draw about 10% of LED.

My needs are simple, typically LED lighting, a roof fan, CO detector, and charging phones. On my Escape the needs are greater with the electrical controls on the fridge (running on propane).

I continue to use my 100w suitcase panel on both of my trailers (one trailer at a time of course). Plan on moving it during the day, depending on where you are located. Love being able to camp in the shade with the panel in the sun.

I'm camping right now. Location A is best for morning sun, location B is best during the day, location C is best in the afternoon.

Lithium batteries continue to drop in price. Its only a matter of time before they become the standard. When my lead acid batteries die, I'll probably go lithium at that time. Until then, my Walmart led acid RV batteries are working fine.

[Perryb67]

Originally Posted by jwcolby123

I never mentioned Lithium. To say "100w works for me" only means it works for you. I think given his usage he may or may not reliably charge fully back up which is a recipe for killing his battery.

Where is he camping? Arizona desert? In the monsoon season? Somewhere where there is cloud cover a lot? Or plugged in every night? PWM or MPPT? From my read that controller is PWM. I have no idea whether the panel provides 100w around the PWM controller. Maybe so.

It sure seems no one is asking the right questions.

Look, a PbA battery requires a bulk cycle, then an absorption cycle. My understanding is that the bulk cycle is about 80%, then 20% is at a slower rate of charge. Which is why it is important to have a somewhat large current during bulk because it gets through that bulk phase fairly fast. You can claim 5 or 6 amps from the panel if you want, but if the battery is only accepting 4 or 3 or 2 amps over many hours, and you only have 6 or 7 hours of solar, then? And if it's cloudy then you might only be getting 3 amps for the bulk phase to begin with, so you never even get to the absorption phase.

I personally don't care who does what, I just object to inaccurate information and "it works for me" kind of stuff. People kill lead acid batteries every day because they don't understand how they work. Let's try to provide accurate and complete information so that people can keep their batteries healthy.

I didn't give any inaccurate information. Please be specific. Even lithium batteries fail.

Do you believe a MPPT is superior to PWM in a simple 18-20v portable? It's not, only on paper. Now when your talking high voltage (+30 volts) or amperage there's an advantage. For most a PWM is all they need. I didn't buy a Victron SCC because it is superior to a PWM, but purchased it because I wanted more information from the controller than a simple PWM gives, especially when combined with our Victron 712 battery monitor.

I could go on, but I'll stop here.

BTW, we have 260 ah's of SiO2 batteries, but I don't get on my soapbox promoting the advantages over traditional lead acid (or lithium for that matter). For many here traditional lead acid is a good choice. I can separate my needs from others.

Enjoy,

Perry

[jwcolby123]

Originally Posted by Perryb67

I didn't give any inaccurate information. Please be specific. Even lithium batteries fail.
...

BTW, we have 260 ah's of SiO2 batteries, but I don't get on my soapbox promoting the advantages over traditional lead acid (or lithium for that matter). For many here traditional lead acid is a good choice. I can separate my needs from others.

Enjoy,

Perry

Perry, I'm not on a soapbox. In your response to me you mentioned lithium as if I am pushing that. I am not. I am pushing complete information. The OP already has a lead acid battery. I never even mentioned lithium, you did. Twice.

Lead acid batteries may be fine for some folks. OTOH many many MANY people kill their batteries over and over and over... because they come here for info and they get incomplete info.

And a handful of folks talk about how they... Who cares that some guy manages to keep his batteries working for 10 years? That is not the norm.

Lead Acid has real issues. It is not God's gift to campers, it is old technology with many problems. If folk want to buy them I could care less, but let's at least discuss them as if they are NOT God's gift to campers, because they are not. And if folks who have them don't deal with the issues they will replace them over and over and over. If we give them good info and they deal with them correctly then maybe they will get 10 years out of them.

So please stop attacking me and discuss the issues.

Thanks.

jwc

[Lynn Eberhardt]

As usual, much more information than you asked for. Simple answer to your question: yes.

[Mike_L]

100 watts of solar power worked well for me with similar use as described. For spring/fall use when there is less sunlight, I went to 160 and that keep my batteries at full charge.

[jwcolby123]

I am losing count of folks claiming "keeps it at full charge".



What I know is that unless you are monitoring current flowing into the battery, knowing that the battery is at full charge is problematic. What I also observe is that few if any of the "full charge" folks are sharing how they know this.


And folks wonder why I dismiss such tripe. I have a distaste for tripe.

[gordon2]

Originally Posted by jwcolby123

I am losing count of folks claiming "keeps it at full charge".

What I know is that unless you are monitoring current flowing into the battery, knowing that the battery is at full charge is problematic. What I also observe is that few if any of the "full charge" folks are sharing how they know this.

And folks wonder why I dismiss such tripe. I have a distaste for tripe.

When I say it, it means that my Trimetric is reporting full charge... but I also know how to use a hydrometer. Just don't feel the need to explain it every time.

Now about that anal tripe... (and political bashing)...