100w portable solar report

The way we are set up, we can take a 3 or 4 days in the shade even when it's cooler out. I'd wait until we went thru 170 ah before I'd fire up the generator and I bet I see sunshine before that.

Unless you were going to use the panel to offset your day time uses while keeping the battery at float after running the generator, I don't think you would need 200w. Amps in float are usually pretty low.

JiminDenver wrote:
Having MPPT and the ability to track helps you hit float early on but really it's how many amps can you produce vs what is needed. Put my 230w poly on the grp 27 with our usual over night drop to 12,5v and it'll be in float in a few hours.

Someone like Roy that uses a lot of power daily and has a limited window of sunlight is going to need a lot of wattage to cover their needs. I took the 8-D down to 12.1v resting, roughly 120 ah and hooked up the 220w mono for 5 hours at 12a. I think it giggled. The battery voltage made it just above 13v and had a long ways to go. It was going to take a lot longer or a lot more watts to get it done in 5 hours.

220 watts solar gets you what, 13 amps per hour, at peak? If you can get that charge rate for 6 or 7 hours... great, still not there. Hit the generator for an hour or so in the morning, at 55 or 80 amps through your charge controller in bulk mode, and your solar panel will get you topped off. Unless you get a lot of sunshine, and no trees to camp under to get solar to do the job every day, you're still going to need a generator on those cloudy days.

Having MPPT and the ability to track helps you hit float early on but really it's how many amps can you produce vs what is needed. Put my 230w poly on the grp 27 with our usual over night drop to 12,5v and it'll be in float in a few hours.

Someone like Roy that uses a lot of power daily and has a limited window of sunlight is going to need a lot of wattage to cover their needs. I took the 8-D down to 12.1v resting, roughly 120 ah and hooked up the 220w mono for 5 hours at 12a. I think it giggled. The battery voltage made it just above 13v and had a long ways to go. It was going to take a lot longer or a lot more watts to get it done in 5 hours.

RJsfishin wrote:
Wow, after all that, I wouldn't trade my $12.95 CMP 12 for nothing ! It operated flawlessly for 3 months, saw 14.4 almost everyday, and got into float mode most days too. My little Honda felt rejected,.....till the sun dint shine for a couple days, had to run it 4 hrs total in 3 months.

RJ is the model of efficiency. Of course, running 190 watts of panel is what got you into float mode so early most days, also. That, and LED lights everywhere. And a really efficient trailer hitch mount that you could aim a few times a day directly at the sun to maximize your harvest.

How many amps are you using in a normal 24 hour period and how many AH do you have available from your batteries?

full_mosey wrote:

Snowman9000 wrote:

...
When on pc, I will comment on lack of float mode. In short, it doesn't matter for my use. Think about it.

Don't worry about the lack float. After the sun goes down, the charging stops anyway. In the AM, the charge cycle starts over.

Plus, during the day, the current will decrease to nothing. I have seen my turnigy read 0A late in the day. That is not going to hurt anything.

HTH;
John

Right, thanks. That's what I was getting at. And at low amps the pulses are spread out quite a bit.

To clarify my comparison with my ebay PWM controller, it drops down to 13.8 in absorption when the MS would still be in the 14's. So it's not going to put as many watts in as the MS controller if time is short. I don't know about RJ's controller, obviously. I'm all for ebay bargains though.

Snowman9000 wrote:
Voltage was 14.4. Morningstar bases its voltage on 14.4/77 degrees. I have to be in absorption mode to see it. The day before, it was in bulk mode all day, hence the lower voltage. Today it would finally get caught up, but we are moving on.

:W simple ain't it. No need to complicate it.

at 2.78 C below 77, the correction is something like 0.078v (28mv/degreeC)!

I guess we all need voltmeters with 3, 4 or 7 decimal places :h

Snowman9000 wrote:

...
When on pc, I will comment on lack of float mode. In short, it doesn't matter for my use. Think about it.

Don't worry about the lack float. After the sun goes down, the charging stops anyway. In the AM, the charge cycle starts over.

Plus, during the day, the current will decrease to nothing. I have seen my turnigy read 0A late in the day. That is not going to hurt anything.

HTH;
John

RJsfishin wrote:
Wow, after all that, I wouldn't trade my $12.95 CMP 12 for nothing ! It operated flawlessly for 3 months, saw 14.4 almost everyday, and got into float mode most days too. My little Honda felt rejected,.....till the sun dint shine for a couple days, had to run it 4 hrs total in 3 months.

Well, when we had an overnight low of 3F, my MS TS 45 PWM in the TT raised the charge volts to 15.45.

At 3F, a battery may not charge correctly with 14.4V.

OTOH, when the batteries were 110F, the charge Volts were 13.29 by the MS SS-10 in the van. Like I said, this controller is inside the battery box in the van.

Say yes to temp comp chargers.

HTH;
John

Edited: the 3F info was not the SS-10 controller.

Yesterday it was in absorb mode all day, but never got full. It was charging at 2.8a at the end, which is a fair bit more than the parasitic loads.

Voltage was 14.4. Morningstar bases its voltage on 14.4/77 degrees. I have to be in absorption mode to see it. The day before, it was in bulk mode all day, hence the lower voltage. Today it would finally get caught up, but we are moving on.

I also have an eBay pwm controller, same one as eco worthy sells. It drops to 13.8 when the sunsaver would be staying in the 14s. I'm on my phone, tired of typing. When on pc, I will comment on lack of float mode. In short, it doesn't matter for my use. Think about it.

Good news on that controller RJ is using. I got a similar one (CMTP02) last year based on an RJ "find".

Only got to use it for a week in September before putting away the solar for the season, but it worked very well, going to 14.4v and holding there.

We had some fun on here about it being a "fake MPPT" which it is, and I call it my "RJ Special", but it is a good PWM controller and I am glad to have it.

I now also have a more expensive ( $34), fancier controller (Solar30) with an adjustable high set-point, an ammeter, and an AH counter built in, that I can make go to 14.8v which I need instead of 14.4v in my latest set-up. So my RJ special will be a back-up in case I fry the Solar30.

I have no problem with the controllers having their temp comp built into the unit, since I mount the controller in the same compartment as the batteries anyway.