Double solar system hookup.

[AWCHIEF]

To me a big system is what you see on houses and industrial uses. Small systems are on our trailers.

[BoldAdventure]

Originally Posted by AWCHIEF

To me a big system is what you see on houses and industrial uses. Small systems are on our trailers.

I would think wattage would be a better factor to determining small vs big.

Since we left Colorado we've mostly been camping in perfect conditions. You get that a lot on the South West. So I wouldn't discount it as being a rare occurrence.

[KJRitchie]

Originally Posted by lewster

Kelvin,

You need to match the MPPT voltage figures (Vmppt) as closely as possible across all panels to be effective when using an MPPT controller. A difference of more than 0.2VDC in panel output voltage will confuse the MPPT function.

If you want to use panels with a greater voltage differential, stay with a PWM controller. In any event, I would not use any panel in a PWM system that has more than a 0.5VDC differential.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
ABYC Certified Master Marine Electrician
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters
541-490-6357

I checked the spec label on the back of my Zamp 200w portable panel.

The panels are 12v, 36 cell (4 x 9). The panels are about 39 1/2" x 26 1/2" dimension.
Pmax = 100 watts @ maximum power
Vmpp = 17.9 volts @ maximum power point
Impp = 5.59 amps @ maximum power point
Voc = 21.6 volts @ open circuit
Isc = 5.93 amps @ short circuit

I prefer the GS100 panels because they are only 40" long and would fit on the front of my 25fb without have to worry about clearing holding tank vents and bath/shower power vents.

Looking at the AmSolar GS100 panels specs
Pmax = 100 watts @ maximum power
Vmpp = 17.7 volts @ maximum power point
Impp = 5.7 amps @ maximum power point
Voc = 21.2 volts @ open circuit
Isc = 6.10 amps @ short circuit

AmSolar SF100
Pmax = 100 watts @ maximum power
Vmpp = 18.0 volts @ maximum power point
Impp = 5.55 amps @ maximum power point
Voc = 21.6 volts @ open circuit
Isc = 5.93 amps @ short circuit
Length = 47.25" (1200mm)
Width = 21.25" (540mm)
Depth = 1.38" (35mm)
Weight = 15.5 lbs. (7.05kg)

The SF100 panels seem a close electrical fit to my Zamp 100w panels and the SF100 kits is $100 cheaper than the GS100.

Given the SF100/GS100 are a close fit with the Zamp, how much performance difference could I expect to see between these panels vs a PWM controller and MPPT controller? Is a 30amp controller the minimum size for this hybrid system?

Thanks

Kelvin

[rodsterinfl]

I found it; at least on the Bogart site about when to use PVM controllers. Note too the bold part, this is what my advisor referred to- that seemingly sliding scale:

The "good" for PWM: It is simpler and lower cost technology.
Under some common circumstances--it can actually deliver more amps to the battery. That could be when:
(1)days are moderate or warm, with few clouds.
(2) batteries are charging at over 13 volts, (in a 12 battery system) which they almost always are when actually CHARGING.
(3) Panel voltage is properly matched to the battery voltage, for example "12V" panels are being used with a 12V system.

I looked up my voltages and the roof is 17.9 Vmp and the other panels are 18.0 Vmp and they are all 12 volt rated. The charge rate is 14.6 Volts on the flooded batts.

PWM is actually more "power efficient" than MPPT--which means less total power loss in the controller itself. So heat sinks in the design can be smaller (and less expensive). Missing in most analysis of MPPT is that there is always a conversion loss with MPPT, which tends to be higher the greater the voltage difference between battery and panels. That's why PWM can actually beat MPPT under circumstances described above.

Given the SF100/GS100 are a close fit with the Zamp, how much performance difference could I expect to see between these panels vs a PWM controller and MPPT controller? Is a 30amp controller the minimum size for this hybrid system?

By the book, like I was given, the simple way is to find the charge rate of your pwm controller and subtract it from your panel voltage, then, find the percentage and deduct that percentage from your panel wattage; HOWEVER, that is the possible loss in a maximum/optimum environment. This does not calculate loss that the MPPT controller has converting, etc. I believe the point is that if you want to pay double or more for a controller and you want to buy higher voltage panels and get the most, then go with MPPT and 24V panels you will optimize the system but then there are other considerations. My thought is that the MPPT is certainly better but probably loses about 10%- my guess from what I am reading so far. That is still less loss but at a cost. Since you are using 12V panels, I do not know if it is worth the extra cost- IMHO.

[lewster]

Originally Posted by KJRitchie

I checked the spec label on the back of my Zamp 200w portable panel.

The panels are 12v, 36 cell (4 x 9). The panels are about 39 1/2" x 26 1/2" dimension.
Pmax = 100 watts @ maximum power
Vmpp = 17.9 volts @ maximum power point
Impp = 5.59 amps @ maximum power point
Voc = 21.6 volts @ open circuit
Isc = 5.93 amps @ short circuit

I prefer the GS100 panels because they are only 40" long and would fit on the front of my 25fb without have to worry about clearing holding tank vents and bath/shower power vents.

Looking at the AmSolar GS100 panels specs
Pmax = 100 watts @ maximum power
Vmpp = 17.7 volts @ maximum power point
Impp = 5.7 amps @ maximum power point
Voc = 21.2 volts @ open circuit
Isc = 6.10 amps @ short circuit

AmSolar SF100
Pmax = 100 watts @ maximum power
Vmpp = 18.0 volts @ maximum power point
Impp = 5.55 amps @ maximum power point
Voc = 21.6 volts @ open circuit
Isc = 5.93 amps @ short circuit
Length = 47.25" (1200mm)
Width = 21.25" (540mm)
Depth = 1.38" (35mm)
Weight = 15.5 lbs. (7.05kg)

The SF100 panels seem a close electrical fit to my Zamp 100w panels and the SF100 kits is $100 cheaper than the GS100.

Given the SF100/GS100 are a close fit with the Zamp, how much performance difference could I expect to see between these panels vs a PWM controller and MPPT controller? Is a 30amp controller the minimum size for this hybrid system?

Thanks

Kelvin

Kelvin,

I would consider all of the panels that you listed to be close enough to 'match' if you are considering an MPPT controller. You typically will not see the benefits of MPPT unless your total array is greater than 200 watts. In that scenario and based on what I see on every system that I install, the Blue Sky controllers will provide you with up to 30% additional charging amperage to your batteries when they require significant charging.

I have many photos of the iPN-PRO remote showing exactly what the 'solar boost' is. Here is one for a large system and a few smaller ones. The smaller system was 300 watts. The largest, 1920 watts.

[KJRitchie]

OK sounds good.
For up to 400w, do I go with the
Solar Boost 2512iX-HV MPPT 25amp
or
Solar Boost 3024iL MPPT 40amp

Most of the time it would be 200w active while towing and in full sun I may not bother to deploy the portable 200w panel.

Kelvin

[BoldAdventure]

The 2512ix is actually rated to 320 watts, not 400 watts.

[lewster]

Right. But counting on panel inefficiency and atmospheric conditions, 400 watts is the practical limit we use.


Lew Farber
RVIA/RVDA Nationally Certified Master Tech
ABYC Certified Master Marine Electrician
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center*AMS Lithium Batteries
Lifeline AGM Batteries**Magnum Inverters
541-490-6357

[KJRitchie]

I'm only saving $100 going with the 2512. If I go with the SF 100 panels then I'm still a little ahead getting the better controller. That way if I do want to add another panel on the roof then I'm good to go.

Kelvin

[lewster]

Originally Posted by KJRitchie

I'm only saving $100 going with the 2512. If I go with the SF 100 panels then I'm still a little ahead getting the better controller. That way if I do want to add another panel on the roof then I'm good to go.

Kelvin

The 3024iL is actually easier to install when it comes to the cable terminals. if your budget allows…..go for it!

[BoldAdventure]

If you are like me you'll eventually one day want more panels, and they'll you'll cry like a baby realizing you should of just gone bigger to start.

[dznf0g]

Originally Posted by BoldAdventure

If you are like me you'll eventually one day want more panels, and they'll you'll cry like a baby realizing you should of just gone bigger to start.

Yup,

I started this adventure with a 15W storage battery maintainer.

Next, decided I wanted to cut down on generator use while boondocking and got a 160W suitcase ( camp in the woods mostly, so rooftop wasn't the sole answer).

Then I decided I needed more than 15W for winter storage, as I didn't want to remove my batteries for winter anymore. Got a 100W panel "just for temporary winter mounting". Then said, "hey stupid, you're paying for a good panel why not mount it permanently and add to the suitcase?"

Is 260W enough for my lifestyle? By the numbers, yes......until the one time I REALLLLLY don't want to set down my beer, get out of my lounge chair and pull out the gennie and cord.

I suspect further expansion is likely. Lesson here: Wire and buy for anticipation, not necessarily for what you think you need today.

[KJRitchie]

The more batteries you carry the more solar you need to charge those batteries in a reasonable time.

I don't plan installing more than 2 batteries, 200-220 amp/hr, so I'm thinking 200w to 400w of solar will meet my needs.

I don't have an inverter in my Airstream. Wife gets percolated coffee when not on shore power. I drink hot tea, water boiled on the stove. We have a small sine wave inverter to run the TV or charge a laptop battery.

Rather than spend several thousands dollars on a decent inverter and the labor to wire it into the 120v circuits I'll just buy a 2000w generator for those few times.

[dznf0g]

Originally Posted by KJRitchie

The more batteries you carry the more solar you need to charge those batteries in a reasonable time.

I don't plan installing more than 2 batteries, 200-220 amp/hr, so I'm thinking 200w to 400w of solar will meet my needs.

I don't have an inverter in my Airstream. Wife gets percolated coffee when not on shore power. I drink hot tea, water boiled on the stove. We have a small sine wave inverter to run the TV or charge a laptop battery.

Rather than spend several thousands dollars on a decent inverter and the labor to wire it into the 120v circuits I'll just buy a 2000w generator for those few times.

Ditto, I could see...maybe...needing/wanting a second 100 watt panel for the roof...but living with my 260 watts will tell. I wired to the roof for more than I have right now though, as that is a pretty big job.

[BoldAdventure]

I started my lithium post on my blog with a description of how annoying the generator is. Now that it's for rare occasions it's perfect. We only invert for two things, my 29 inch monitor and our 260w blender. That's it. Everything else I have 12v plugs for or have hardwired into the power system. My stand by right now is 3.2 amps and when I'm working with both laptops charging we're around 18 amps of use. That drops to 10 amps for about 8 hrs once the laptops are charged. So I am always deducting power from my system during the day. Anyways, these challenges are unique to my situation.

-------------

For a long time I was confused by the relationship between batteries and solar panels. For some reason I just couldn’t wrap my head around it. I finally figured it out and this is best way I can explain it is to pretend that electricity flows the same way as water: a battery is like a bottle while a solar panel is like a funnel. The sun “rains” energy down and it’s caught by the funnel. The more solar panels you have the bigger your funnel is and the more batteries you have the larger your bottle is. A bigger funnel means you can catch more rain and fill your bottle faster; the more batteries you have, the larger your bottle is and the more water you can hold. So the bigger your funnel, the faster you can fill your bottle. To me, it's those days with clouds that I am now focused on.

[SCOTTinNJ]

Nice Bold, but at some point you run out of space for funnels and bottles, even with unlimited funding.

[rodsterinfl]

I don't plan installing more than 2 batteries, 200-220 amp/hr, so I'm thinking 200w to 400w of solar will meet my needs.

I don't have an inverter in my Airstream. Wife gets percolated coffee when not on shore power. I drink hot tea, water boiled on the stove. We have a small sine wave inverter to run the TV or charge a laptop battery.

Rather than spend several thousands dollars on a decent inverter and the labor to wire it into the 120v circuits I'll just buy a 2000w generator for those few times.

Intended use is key to the whole solar thing. One thing that I have noticed is how critical direction/tilt is to solar collection. I wired an inverter but did not hook it into the trailer's wiring. While it limits me to inverters with built-in outlets, it works great. You might consider that option.

[dznf0g]

Originally Posted by rodsterinfl

Intended use is key to the whole solar thing. One thing that I have noticed is how critical direction/tilt is to solar collection. I wired an inverter but did not hook it into the trailer's wiring. While it limits me to inverters with built-in outlets, it works great. You might consider that option.

Likewise for me. I only typically use the inverter for LED TV, Blue Ray, and device charging. I really don't need it for kitchen appliances, etc., so I mounted a 600W Zantrex between the side of the sofa and the arm storage wall with Velcro. On the rare times I need the TV and Blue ray, I just run an indoor extension cord to the credenza.

[rodsterinfl]

Likewise for me. I only typically use the inverter for LED TV, Blue Ray, and device charging. I really don't need it for kitchen appliances, etc., so I mounted a 600W Zantrex between the side of the sofa and the arm storage wall with Velcro. On the rare times I need the TV and Blue ray, I just run an indoor extension cord to the credenza.
__________________

I DO run appliances from the inverter. It works just fine. I run a coffee grinder, coffee maker, and flash oven- so far and not all at once. I stay about 200 watts from the max continuous rating to be safe. I have 350 watts charging 184 amp hours providing me with 1104 watt-hours. I haven't run into an issue yet. I use what I need and unplug it as soon as possible. My highest wattage is 1300 watts for 10 min or so. That is about 217 watt-hours and, that, only when I use the toaster. Everything else is less power. My full recharge time is just under 5 hours solar at optimum sun. It is much less since I do not use all 1104 watt hours.