Solar Panel Round-up: what wattage do you have?

seanahrens · 10-14-2015, 09:23 PM

I'm hoping we can get a bunch of people to post a short summary of their solar set up and whether they've found it produces enough power.

Just quickly post answers to these questions:

1. How many total watts of solar panel(s) you have? And how many amp-hours is your house battery?
2. For your power usage, have you found it: insufficient, sufficient, or more-than-sufficient?
3. Describe your power usage and give the model of your vehicle (mostly so we know what size space we are talking about lighting up, heating (if electrical), etc)

Thanks!

seanahrens · 10-14-2015, 09:29 PM

I'll start:

1) 80W (and it's a 2004, so over 10 years old right now. Might mean it's less efficient?). I have a 210 4D AGM Lifeline Battery.

2) Insufficient

3) I have a Ford E350 EB SMB. I've found that my battery will have a negative charge (be constantly draining) with minimal electricity usage: LED overhead lights, refrigerator on it's lowest setting, some stereo, and USB charging of phone. I almost never run the 110v inverter because the drain on the system is unacceptable. I'm looking to upgrade my solar panels probably to at least 150W, but trying to figure out the right amount without taking up too much roof space.

boywonder · 10-14-2015, 09:45 PM

...you may want to add battery capacity to the survey..........and typical use case.

120W panel

350 amp hours of house battery capacity at 20 hr discharge rate

E350 RB.....sufficient for keeping the batteries fully charged while sitting in the driveway and for powering everything for a 2-3 day trip, (LED lights, truck fridge TF49, 1000W inverter powering microwave)

larrie · 10-14-2015, 10:02 PM

1. 270 watts from two 135 watt panels
2. Group 31 deep cycle RV battery about 105 AH
3. 1989 RB will keep the furnace, fridge, LED lights operational through the night. Starts charging the battery in the morning as soon as the sun is above the horizon.

**daveb** · 10-14-2015, 10:35 PM

Twin 135w panels & MPPT controller.

Twin 4-D 210AH Lifeline batteries.

Enough to run 3-4 amp heater or fan all night long with enough reserves for stereo and LED lights till about midnight. It also runs my brand new power hog Norcold that cycles on at a whopping 6 amp while running. With that I can also run my microwave for a few minutes w/o running the engine. Prior to light, the resting voltage is usually 12.3-12.4 & usually up to full charge by 9-11am depending on the evening draw down in reasonable morning sun.

photographix · 10-15-2015, 12:38 AM

1. Two Kyocera 140 W panels = 280 W and MPPT controller. Two cheapie Walmart Everstart Group 29 Marines, 110 AH each.

2. Panels are more than sufficient, achieving float stage about 3 to 4 hours after sun-up.

3. Ford E350 EB, with an SMB canvas-sided pop-top. All lighting has been converted to LED bulbs, Norcold 2.5 cu fridge set at 3 all the time, propane heat with Suburban 16 furnace (electric propane tank valve draws a bit of current just being open, as we found with our old weak batts), or portable Fantastic Fan for summer. On-board potty with electric water pump used at least 2-4 times per night, plus brushing teeth, washing up, and cleaning dinner dishes. Can run the TrippLite inverter to microwave dinner after dark. Use 12V chargers for phones and tablets during the night. Don't have a TV. Usually wake up to batts at around 12.3 (winter) to 12.5 (summer) in the morning.

schluchtenflitzer · 10-15-2015, 04:10 AM

Two Kyocera 80? W panels = about 160 W and Blue Sky controller.
One 100Amp AMG Solar Batterie

Never had problems with an empty batterie even if the weather is bad. I only run my fridge (norcold) with it and in my cabin are only LED lights.

Viva · 10-15-2015, 01:02 PM

I'll post the basics you asked for, but then I'm going to add more below in case it is helpful to anyone. This'll be below the line of asterisks, so anyone can just skip it if they want to.

1. How many total watts of solar panel(s) you have? And how many amp-hours is your house battery?
200 watts for now. 375 amp hours.

2. For your power usage, have you found it: insufficient, sufficient, or more-than-sufficient?
More than sufficient most of the time, in terms of wattage. For more detail, see below.

3. Describe your power usage and give the model of your vehicle (mostly so we know what size space we are talking about lighting up, heating (if electrical), etc)

Around 35-50 amp hours per day. I have an E-350 chassis very small Class C with about 500 cubic feet of "house" space in the rear - although much of that is taken up with cabinets of course. I block off the cab when camped. Heating is via propane, with no electricity required (although optional fan which has minimal draw).

*******************

My use case scenario is primarily boondocking, with maybe a week or two per year plugged in (visiting a friend, a night at a campground, etc.)

--My one "relentless" draw is a compressor refrigerator, that draws 25-30 amp hours per 24 hour day (may go to larger one which would likely draw 30-50 ah per day, although maybe with better insulation the jump wouldn't be that much).
--My biggest optional draw is charging laptop/phone/AA batteries [camera, flashlights, etc.]. That's around 10 amp hours per day, but can be eliminated if necessary.
--Other minimal draws are LED lights, marine fan, propane detector, water pump. These either draw very little or are used very sporadically so don't add up to much.

I started with a plan to allow for 400 watts of solar, but actually put in the base wiring and components first (batteries, cables, OCP, etc.) I was more sure on what I wanted in the latter, and not 100% sure how much solar I would need (and the more I have, the more awkward it is on the roof, plus the money, weight, etc.).

So the "base" consists of three Group 31 AGM batteries, for a total of 375 amp hours. Charging methods are by generator or charger/shorepower (although those are not connected for now as the AC electrical system is my lowest priority and I'm taking care of it last), alternator (via manual combiner switch), and solar, via MPPT charge controller. I monitor via Victron BMV-700 and Balmar Smart Gauge.

A friend with a similar use case has 500 watts of solar and still draws the bank down pretty often (by "down," I mean 60% or so). And he has a propane refrigerator. He also parks in the direct sun as much as possible (I like shade). So I worried that even 400 watts would not be enough. But I still wasn't sure. I did calculate things, but there are always variables such as what is the duty cycle of the refrigerator, what will happen on cloudy days or places where I only get a few hours of sun on the roof, etc.

I had two 100 watt lightweight/thin panels plus a small MPPT controller on hand for another project, so I decided to hook them up as portables over this summer while I sussed things out and collected real-world data. I put them in series for higher voltage and less voltage drop, which enabled me to run a 35' 8/2 cable between the controller and the panels and still stay under 2% voltage drop for the whole thing (including cable from controller to batteries and battery jumpers themselves). I crimped MC4 connectors onto the end of the 8/2 and use those to attach to the panels (I filed off the locking tabs so I don't have to use a tool each time - they still stay firmly connected and the O-rings engage).

What had stopped me from considering this type of arrangement in the beginning was .... where on earth would I put the panels when underway?! It just sounded like a hassle. But it seemed worth it for a trial before mounting "permanent" panels on the roof (which would be rigid aluminum/glass type). Then I discovered the portables would fit upright behind the drivers seat (between it and the aisle type gaucho couch), and not really even take up any "real" space. I just used the original box they came in and a fleece "pillowcase" to protect them inside it. The box is about 23" x 42" x 2".

So I spent the summer with this setup. Of course this is the "best" season, and you really want to plan a setup for the worst, but it was the time frame I had to work with. I found that my batteries rarely got below 95% if I had the panels out every day. And the refrigerator had a lower duty cycle than I thought it would (I had planned for it to draw 48 amp hours per day; it so far has done about 25-30). I didn't want to draw the bank down too far, because as things stand now I'm "over batteried" as compared to my panel wattage, so I could theoretically dig myself into a deep hole that would be hard to climb out of with only 200 watts. But with mostly sunny weather this was no issue at all. I think I would be fine with a smaller battery bank if I were sticking with 200 watts of panels - say 200-250 amp hours.

As it came into fall, I also happened to move to a more shaded place, plus of course sun angle was lower. I was still able to keep up, but didn't get back to 100% as ridiculously soon in the day as I did with full summer sun. Then one of my panels failed (diode failure) so I had to go on just one panel for a couple of weeks. That did make it a bit dicey, between the one panel, the fact that I started out a bit in the hole (took a bit of time to figure out what the problem was), and I was in the deep woods with low angle fall sun. I was able to keep the batteries up, but only by moving the single panel around and propping it up for best possible gain. Not something I would choose for a final setup.

The other time this system is a hassle is, say, a two-day stop. Or a one-day stop that turns into three days. I'm mostly charged up when I stop (in this type of move I may connect the alternator, although normally I don't because why use a "stupid charger" if the smart solar charger can keep things up on its own), but even though it's not THAT hard, of course I'd rather not bother to put out the panels. Or maybe it's a place where I don't want to (last week I was in a "parking lot" type of camp, and gone all day, so not that eager to put them out). Or a short stop turns into "another day" and oops, should have put the panels out yesterday.

Upshot is... I love the portable system and plan to keep it as part of the real setup. Many times I was parked in deep shade when my buddy was out roasting in full sun so as to keep his roof panels working. I just ran the cable out so the panels were in the sun most of the day. This rocked. But I want to ameliorate the negatives mentioned in the previous paragraph.

So now I've changed my overall plan. Originally it was 400 watts on the roof (rigid/glass panels). But now I don't want to give up the ability to park in the shade and have the panels in the sun, so the portable panels are going to stay. What I would like is enough wattage "permanently" on the roof to take care of a shorter stop, so that I only have to put the panels out sometimes (longer stays, super shady camp spot). Or to supplement on cloudy days. The roof panels would also make it so I don't have to charge with the alternator. The solar charger is much more finely tuned in terms of charging profile, so I'd rather only use that on my AGM house bank. So now I'm thinking 200 watts on the roof (two 100-watt panels, in series), and then the two portable panels I'm already using. These are close enough in spec that I can run them on a single controller. I'll only put the ground panels out for longer stops, or places where I can park in the shade and I then see the roof panels can't keep up.

I realize you just wanted a list, but I figured it might be helpful to explain more. I would not have minded reading something like this when I was planning.

PS: As it turns out, the buddy whose 500 watts are enough but not really "generous" uses a LOT of power running an inverter and large computer (requires AC power). I hadn't realized just how much that required, and that my "relentless" compressor refrigerator (vs. his propane one) would actually be much less thirsty than that.

LenS · 10-15-2015, 02:19 PM

2 100 watt Regony panels wired in series w Regony controller
215 Ah Interstate 6v batteries (2 of them)
added mainly for refrig that draws 50Ah per 24 hr period (72F day).

Installed this year.
viewtopic.php?f=14&t=16436

86Scotty · 10-15-2015, 05:08 PM

100 watt Renogy panel

2 110? amp hour Deka AGMs

Insufficient.

I run a Truckfridge and all LED lights in a RB Sportsmobile. It last almost 2 days but I would say a full weekend without moving the van is an ideal solar setup, so in my situation I think 200 watts of solar is the minimum.

I do have an 1500 watt inverter/charger and if I turn it on (to use the microwave, usually) I just start the van and the alternator compensates just fine for those rare minutes.