e9999, have you done any testing on different types of solar panels to see which construction/method has the best efficiency ? I currently run a Lensun semi-flexible 100W and it amazes me at it's output in what I think in insufficient light. I was also curious regarding the osciliscope pattern you posted for the inverters and what that looks like for solar, i.e. - does a solar charge controler need to be PSW to recharge battery best or is it a non issue ? I have never payed attention to wether the solar stuff is PSW or not ? I guess I am wondering if the wave shape that may effect electronic devices is also important in battery recharge ?
All electric camping?
- Thread starter ntsqd
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ntsqd
technerd
- Thread starter
- #42
The US RV industry is geared up to sell junk at the lowest possible price for the highest possible margin. There are exceptions, but the majority of mfg's and in particular retailers are a half-step up from the stereotype of a used car salesman.
Two weekends ago I was in Winters, CA staying a the Winters Hotel (not inexpensive, but is recommended). We were on the 3rd floor and one day I looked out across the street. As it happens their local NAPA is there. Both roofs of the building were covered in solar panels. Solar panels were covered in dirt. I doubt that they're getting 1/10th of the wattage that the panels are capable of just due to the dirt on them. Given that they're in an Ag area I imagine that keeping those panels clean would be an on-going, weekly effort.
Two weekends ago I was in Winters, CA staying a the Winters Hotel (not inexpensive, but is recommended). We were on the 3rd floor and one day I looked out across the street. As it happens their local NAPA is there. Both roofs of the building were covered in solar panels. Solar panels were covered in dirt. I doubt that they're getting 1/10th of the wattage that the panels are capable of just due to the dirt on them. Given that they're in an Ag area I imagine that keeping those panels clean would be an on-going, weekly effort.
FrazzledHunter
SILVER Star
I think you're correct in the sense that the US RV industry does get it in that it knows its market. The US market simply won't pay what it costs to do true off grid. Those that do get the solar off-grid packages I am guessing aren't really doing it. It's more of a "Oh look George it's got solar panels so we won't use so much electricity while at the KOA". I got this explanation from a couple of RV vendors, btw. It was incredibly refreshing to hear that.
However, many of the "discussions" I had with the RV vendors justifying their ridiculous (IMHO) designs and how I didn't need anything else other than what they were selling were absolutely infuriating. Their numbers simply didn't add up.
Yes and it's not limited to the users. Most of the RV vendors, at the least the ones doing the selling that we encountered, didn't know a Watt hour from an ohm. But regarding the solar industry, they only have themselves to blame IMHO. They advertise a 200W panel that would never get nearly that in practice but they don't mention that in the advertisements. I know of only one vendor, Merlin, that advertises the the output ( or very close to it) of their solar panels. I have a Merlin XP-170 portable panel whose advertised output is 170W and I've gotten over 150W in full sun in the mid-atlantic region and almost 170W in the FL everglades.
I guess it's like EPA fuel estimates. Your mileage may vary.
FrazzledHunter
SILVER Star
I'm in 100% agreement with you regarding the RV industry. But I think you've insulted used car sales people.
P, what you'd hope for out of a charge controller is a DC output, not a sine one. (It's very different from the inverter situation.) I trust that Victron would have that figured out. I don't recall if I ever checked, but if I did there must not have been anything unexpected. I may do that again now that you mentioned it. But in any case, it does not matter much for battery charging, I think. Batteries (FLA at least) are very forgiving. Old style chargers were rectified square waves. And a PWM charge controller is also a square wave some of the time. I don't think that would hurt an FLA battery one bit. Now, with a LiFeP one with some fancy BMS on top, I don't know what would happen. But I've never read that it's a problem.
I also bought a flex panel to check it out. It works fine and is delightfully lightweight. But from a practical point of view, I realized too late that these things should really be glued in place and never moved again unlike what I'm using it for. I'm freaking out every time I bend it a bit, not good for my mental health...
I also bought a flex panel to check it out. It works fine and is delightfully lightweight. But from a practical point of view, I realized too late that these things should really be glued in place and never moved again unlike what I'm using it for. I'm freaking out every time I bend it a bit, not good for my mental health...
How often do you all clean those solar panels when camping? Do you give them a wipe down every day?
Does anyone have a hood panel, like Lensunsolar offers? They seem to have one for every common offroad truck now.
Glued on permanently, but rock chip susceptible. I agree with above sentiments, solar dealers don't really explain
very well. I find more proper valuable info on this thread than what they publish and lets face it, I can't ask the right
questions because I really don't know what to ask.
Does anyone have a hood panel, like Lensunsolar offers? They seem to have one for every common offroad truck now.
Glued on permanently, but rock chip susceptible. I agree with above sentiments, solar dealers don't really explain
very well. I find more proper valuable info on this thread than what they publish and lets face it, I can't ask the right
questions because I really don't know what to ask.
ntsqd
technerd
- Thread starter
- #47
A friend of mine in the power generating industry told me that tests at one of those massive 'solar farms' that we're seeing start to cover the SW desert showed that PV's perform their best when the backside is as cool as you can possibly make it. Since then I've modified the PV frames with holes up close to the backside of the actual panel at one end and I've always mounted the panels such that the end with the holes in it is ~1/4" higher than the opposite end. It's probably down in the 1/4 of 1% improvement but it makes me feel good to do it.
Because of that I hadn't planned to buy any flexible panels unless I can glue them to a serious heat sink, but the RTT on the Wagon may force my hand.
Because of that I hadn't planned to buy any flexible panels unless I can glue them to a serious heat sink, but the RTT on the Wagon may force my hand.
FrazzledHunter
SILVER Star
The folding Merlin portable solar panels didn't really ever get dirty. However, our trailer's solar panels lay flat on our trailer's roof and I got up there every other day when we were camped on the beach. I assumed sand would blow up there and lay but they stayed surprisingly clean. Maybe due to wind? So now I get up there and clean them with a squeegee and Windex when we get to camp. Then I take a look once a week. Maybe future destinations will change that. I take an Xtend + Climb* ladder with us so it makes getting up to the trailer's panels easy.
Merlin XP-170 folding solar panels complementing the 400W (as advertised) rooftop panels at Oregon Inlet NC, our favorite beach campsite so far:
*Ref:
Telescoping Ladders for Sale - Xtend + Climb - https://xtendandclimb.com/
IME, dirt on the panels is not as big as factor as one might fear. You would think the output would plunge dramatically with just a bit of dust but I did not see that.
Yes, the output does decrease significantly due to increase in panel temperature. That factor is normally stated in the panel specs in % loss / oC. That is also why the hood is not the best spot for a glued panel. If you take a panel from your cold garage, say, and put it out in the sun, and measure the output, you'll see it drop significantly in the first few minutes as it gets hotter. Unfortunately, the panels are rated at 25oC, which is quite low compared to what you'd normally get out there in the summer, so these ratings are already overoptimistic just for that factor.
Yes, the output does decrease significantly due to increase in panel temperature. That factor is normally stated in the panel specs in % loss / oC. That is also why the hood is not the best spot for a glued panel. If you take a panel from your cold garage, say, and put it out in the sun, and measure the output, you'll see it drop significantly in the first few minutes as it gets hotter. Unfortunately, the panels are rated at 25oC, which is quite low compared to what you'd normally get out there in the summer, so these ratings are already overoptimistic just for that factor.
ntsqd
technerd
- Thread starter
- #50
I have not done anything that remotely looks like a study on it, but even a eyeballic ~10% panel obscuration drops the output of the panels on my current camper's roof by a notable amount. Perhaps since this a tree shading a portion of a single panel that has more impact than the whole panel being slightly "shaded"?
yes, with real shade you can very quickly stop the panel completely. Does not take much at all, but depends a lot on where the shade spot is wrt to the wiring of the cells. Most panels have the cells wired "vertically" when the panel is "vertical", I think. So if you have some shade "horizontally" and it stretches across the panel, then there could be no or very little output, even if the shade is fairly skinny, like from a tree limb or possibly a cable. But if the shade is "vertical" you can probably still get a significant fraction of the nominal output, depending on the bypass diodes locations. Now, if you have a "parallel" panel with 2 halves and the diodes/junction box at mid height, you can still get 1/2 the output if one half is completely shaded. Those are much better in that regard.
All in all, in the big picture, if you buy a 100W panel, it is almost a miracle to get 100W out of it, even at solar noon in the middle of the summer, given all the factors like temperature, weather, orientation etc. Add to that the reduced insolation away from noon, and I certainly would not count on getting close to the nominal output when sizing up a system.
All in all, in the big picture, if you buy a 100W panel, it is almost a miracle to get 100W out of it, even at solar noon in the middle of the summer, given all the factors like temperature, weather, orientation etc. Add to that the reduced insolation away from noon, and I certainly would not count on getting close to the nominal output when sizing up a system.
ntsqd
technerd
- Thread starter
- #52
100w at 17-ish volts = ~5 amps. As I recall that first fridge drew 2.3A when running (not a very big fridge) and by observation I'd estimate a 60% duty cycle at the hottest time of day on the hottest trip that I can recall taking it on, so even at 50% of panel rated output I still was golden.
That camper now has something like 480w of panels on it. I've no idea what he is doing that needs that much power, but I'm glad that I don't have to lift that roof!
FWIW, those NAPA panels weren't just a little dirty, they were brown.
That camper now has something like 480w of panels on it. I've no idea what he is doing that needs that much power, but I'm glad that I don't have to lift that roof!
FWIW, those NAPA panels weren't just a little dirty, they were brown.
Nicely, one positive feature of the PV approach with a fridge is that you normally get the most power when it's the hottest time of day, so when the fridge needs it most, IOW a good match there. But not a big factor if you have a sufficiently large battery bank, of course.
Seems having good battery support is quite necessarily as important as solar panel input. I have a friend in
Australia with a caravan and he spent on batteries more than panels I think. Do all of you guys here use Lifepo4
batteries? For now I live on my 2 series 31 batteries, but my only real draw is the fridge. But I don't boondock
like some, which I'd like to change.
Australia with a caravan and he spent on batteries more than panels I think. Do all of you guys here use Lifepo4
batteries? For now I live on my 2 series 31 batteries, but my only real draw is the fridge. But I don't boondock
like some, which I'd like to change.
BTUs, I thought you guys fought a war to get rid of the British. Now I find that you are still in love with them. Next thing you will be going to the pound sterling.What are those Jools and litres you are speaking of? Why do you hate America? BTUs, BTUS! Gallons, GALLONS!
nerdish freebie #2: 1 canadian gallon = 1.2 US gallons! so much for the better mpg of canadian landcruisers...
^^ CP: I may still buy a FLA battery for starting my vehicles -until something better comes along at a good price, that is- but I sure as heck won't buy one for any other use. I mean the number of cycles you can get out of an LFP one, the so much smaller weight, the fact that you can actually use most of the energy stored and oh did I mention the weight? No contest, especially since the significant drop in price of the last year or 2. I could still maybe think of getting an AGM deep cycle not too long ago, but not any more.
joseywales
Renaissance Redneck
I own a company that builds custom RVs. I am well versed in the modern tech in the camping industry. My desire for propane fridges comes from appreciating the speed at which propane cools an absorption fridge, not needing gobs of solar to keep batteries topped up, the outright insanity of the cost of lithium batteries (both fiscal and environmental), and the potential fire hazards associated with lithium power. One of my parts suppliers is actually advertising special fire blankets to save people from lithium fires in their vehicles. Propane is obviously flammable too, but propane valves can be closed, and the fire extinguished, unlike lithium fires which will burn until all is consumed. No thanks.
I will be running an old Dometic fridge in my new personal trailer I’m building right now. And I will be using one 150w panel to keep my single AGM battery charged. I won’t be glued to a battery monitor or looking for a charging station to keep driving after spending an hour “refuelling”.
I just watched the final episode of The Grand Tour, and Jeremy went so far as to say the electrification of vehicles of all sorts has in no small part lead to their decision to end their careers in automotive journalism after 22 years on TV. Him being fat and old might be part of it too, but I’m not far behind in both departments, so I won’t hold that against him.
joseywales
Renaissance Redneck
Hey Spey! You know, I moved to the Lake. We should meet up one day since I’m only 10 miles away…BTUs, I thought you guys fought a war to get rid of the British. Now I find that you are still in love with them. Next thing you will be going to the pound sterling.
^^ What lithium fires are those? I am only talking about Lithium Iron Phosphate batteries here as a house battery in a truck or RV. I think that is what just about everybody else is talking about. And as far as I know there is no significant danger of fire with those. Do you know otherwise?
ntsqd
technerd
- Thread starter
- #60
I think that those 787 emergency exit battery fires created a pervasive fear of Lithium batteries, even if you've never heard of that specific series of incidents.
A lithium battery overheating is no joke. If you ever see an EV on fire, get up-wind RIGHT NOW and do not try to put it out w/o SCUBA type gear on. I'm extremely serious abut this. Inhaling those fumes is muy, muy bad for you. Way back in the pre-pubescent days of EV's I met a young guy who got caught in one of those exothermic events and it messed him up badly. After he finally got out of the hospital (MONTHS) he looked and moved like a Polio victim. It would sadden, but not surprise me to learn that he's dead now and has been for a decade or more.
That said, everything that I've found on LiFePO4 batteries says that they do not suffer from the same sorts of problems that the LiPo batteries do. If there are scholarly articles out there to the contrary I'd like to read them.
A lithium battery overheating is no joke. If you ever see an EV on fire, get up-wind RIGHT NOW and do not try to put it out w/o SCUBA type gear on. I'm extremely serious abut this. Inhaling those fumes is muy, muy bad for you. Way back in the pre-pubescent days of EV's I met a young guy who got caught in one of those exothermic events and it messed him up badly. After he finally got out of the hospital (MONTHS) he looked and moved like a Polio victim. It would sadden, but not surprise me to learn that he's dead now and has been for a decade or more.
That said, everything that I've found on LiFePO4 batteries says that they do not suffer from the same sorts of problems that the LiPo batteries do. If there are scholarly articles out there to the contrary I'd like to read them.
