Solar Inverter Low-Voltage Warning/Shutdown
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Doggydogworld
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I now think this is cumulative Ah out of the PWM unit. It went from 2.088k Ah last Friday night to 2.186k and now 2.209k Monday afternoon. That's only ~45 Ah/day.
He also mentioned a box fan, humidifier and some other items. Unfortunately his inverter doesn't report consumption data. That's why I suggested a Kill-A-Watt.
I think the Starlink antenna pulls ~70W. Or maybe that's the whole system, including a router. Speaking of Starlink, how's the performance and reliability so far?
Doesn't explain why it happens every night, though, and so soon after sunset. Besides, most of his 24hr load is being supplied directly by the generator at night or solar during the day. The battery only carries the load a few hours, so divide that 1825Wh by 6 or so.
In fact, his battery should be getting charged by the generator all night and be at ~100% SOC when he switches to solar in the morning. On days with good sun it should stay at 100% until the sun gets low.
@Josh M. - I got 150W by multiplying your Volt and Amp readings out of the PWM SCC. Power = Volts * Amps.
Starlink is the best internet of any sort we have ever had. Speeds, range, performance, and reliability have been great. Customer support/service...basically non existent. But hopefully you won't need it.
My solar battery bank is not hooked up to my generator. Totally separate systems, so this doesn't apply.
Got it. Thanks for the explanation.
Maybe if I tell you guys what a day looks like for us, power consumption-wise, you could help me figure out what I need to do to my system to get it handle it all? Of course I'll need to build up to it due to limited finances and we'll need to make adjustments to our way of living and supplement with the generator until the solar is expanded enough. But if I know what I need, I can have a realistic idea of just how deficient my system is and can make a plan of expansion. I've tried several calculators on websites like Renogy, but they never cover everything or they don't cover items I have for the duration I use them. Only thing is, there are some things that we don't use every day, like the RV Washer and Dryer and my Traeger BBQ so I'm not sure how you factor those things in. But here's the normal day/week...
Work Laptop 17" MSi model ms-1759 - 10 hrs/day, M-F. - 19.5V 6.15A
Starlink Satellite internet - 19 hrs/day, 5 days/week - 60-70W
Magic Chef 10.1 cu ft fridge/freezer (297kWh/yr) 24/7 - ~1000W
Microwave - 900W - 2-5 min/day.
SeaFlo-33 On-demand water pump - 1 hr/day Sun-Friday. 3 hours on Saturdays for laundry. - ~85W
Box fan - 5 hrs/week. - 107W
Desktop PC - 2 hrs/day. - ~200Wh
24" TV - 4 hrs/night. - 29W
15" laptop (for streaming service to TV) - 4 hrs/night. - 19v 3.2A
Amazon Echo - 2 hrs/week. - 2.95W
Humidifier - 9 hrs/night. - ~50W
On Demand propane hot water heater - 9 hrs/wk. - can't seem to find this number
Phone chargers (2ea) - 9 hrs/night. - ~5W
Traeger BBQ - 300W the first 5 minutes/50W thereafter - 2 hrs/wk.
RV Washer - 240W - 4 hrs/wk.
RV Dryer - 850W - 3 hrs/wk.
Vacuum - 15 min/wk. - ~500W
Crockpot - 4 hrs/wk. - ~150W
Breadmaker - 2 1/2 per wk. - ~600W
Popcorn machine (air popper) - 10 min/wk. - ~700W
The more we can do to reduce how much we rely on the generator, the faster we can improve our system. We are currently spending about $500+ a month on gas for the beast.
If you guys can help, I'll be forever grateful!!
Work Laptop 17" MSi model ms-1759 - 10 hrs/day, M-F. - 19.5V 6.15A
Starlink Satellite internet - 19 hrs/day, 5 days/week - 60-70W
Magic Chef 10.1 cu ft fridge/freezer (297kWh/yr) 24/7 - ~1000W
Microwave - 900W - 2-5 min/day.
SeaFlo-33 On-demand water pump - 1 hr/day Sun-Friday. 3 hours on Saturdays for laundry. - ~85W
Box fan - 5 hrs/week. - 107W
Desktop PC - 2 hrs/day. - ~200Wh
24" TV - 4 hrs/night. - 29W
15" laptop (for streaming service to TV) - 4 hrs/night. - 19v 3.2A
Amazon Echo - 2 hrs/week. - 2.95W
Humidifier - 9 hrs/night. - ~50W
On Demand propane hot water heater - 9 hrs/wk. - can't seem to find this number
Phone chargers (2ea) - 9 hrs/night. - ~5W
Traeger BBQ - 300W the first 5 minutes/50W thereafter - 2 hrs/wk.
RV Washer - 240W - 4 hrs/wk.
RV Dryer - 850W - 3 hrs/wk.
Vacuum - 15 min/wk. - ~500W
Crockpot - 4 hrs/wk. - ~150W
Breadmaker - 2 1/2 per wk. - ~600W
Popcorn machine (air popper) - 10 min/wk. - ~700W
The more we can do to reduce how much we rely on the generator, the faster we can improve our system. We are currently spending about $500+ a month on gas for the beast.
If you guys can help, I'll be forever grateful!!
Last edited:
Bud Martin
Solar Wizard
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You need to provide more info on some of the items on your list that do not show any power requirement, there should be sticker that tell you the Voltage and the current it needs to run.
You should get Kill-A-Watt meter to monitor the device for a couple of days to get the idea how much power you are consuming for each device.
You should get Kill-A-Watt meter to monitor the device for a couple of days to get the idea how much power you are consuming for each device.
Thanks! Updated my post above as best I could.
Here's another question.
I just saw a post on another forum where a guy said you could hook up 4 12v 105Ah batteries in series/parallel to make 24v 210Ah. But, he did not say how. Is this BS or is it legit? If it's legit, is that something I should consider once I figure out my battery issue?
I just saw a post on another forum where a guy said you could hook up 4 12v 105Ah batteries in series/parallel to make 24v 210Ah. But, he did not say how. Is this BS or is it legit? If it's legit, is that something I should consider once I figure out my battery issue?
MichaelK
Solar Wizard
OK, in response to your post #29, about your power consumption-wise, here are the highlights. I didn't bother listing every single item, just the bigger drawers....
Work laptop: 1200Wh/day
Starlink: 1235Wh/day
Frig: 813Wh/day
TV: 120Wh/day
15" laptop: 240Wh/day
Adding up just these items I'm seeing 3600Wh/day. Let's guess and say another 400Wh for everything else. Assuming you get 5.0sunhours in June, and 2.5sunhours in December, right about now towards the equinox, you'd expect ~3.75sunhours. So, you are trying to pull 4000Wh out of a system that can't make more then ~3.75sh X 800W = 3000Wh, and a battery that only holds 105Ah X 24V = 2520Wh.
This the kind of planning you should have been doing from day 1. Like the old saying goes, you didn't plan to fail, you failed to plan.
In response to your question in post #32, of course wiring batteries in series/parallel is legitimate. It's a strategy that's been practiced for generations. Just search this site for series/parallel wiring diagrams. BUT, that is NOT what I would recommend you do. Most likely your batteries on hand are already damaged, and pairing a second set in parallel is likely to drag set 2 down the the level of set 1, so you are just throwing away more money.
You are already wasting 500$ each month for gasoline, so I think this is money better spent upgrading your system. For my own system, I hadn't used my generator in so long (2+ years) that the piston rusted in the cylinder, so I think you can use this advice.
First, get rid of the PWM controller. Buy a MPPT controller like Epever's 6415AN, which is ~320$ on Ebay right now. Buy some 72-cell grid-tie panels in the 300W range. Get two so you can you can wire them in series to get ~70VDC. That is about 150$ on Craigslist right now. That's 320$ +150$ = 470$ so you still have a bit left for some gas money.
Then re-wire your original 100W panels as 4S2P. Added together, 600W + 800W will give you 1400W, which should make you about 5.25kWh of power this time of year. Alternatively, just get two 300W panels to start, but be ready to add 2 more if it looks sorely needed.
Once you have the additional solar in place, I'd say it's time to upgrade the batteries. I would not keep adding additional strings of 105Ah batteries, assuming the first string is already going bad. 500$ from month two would get you nice 250Ah golf-carts. Trojan T-105s are ~130$, so four of them would eat up the 500$ of gas money for month 2. But, once you have the new batteries in place, you are likely to have enough power to get you through the night without dropping below 50% charge, assuming you leave the refrigerator on.
6000Wh is still not a lot of battery, but in month 3 or 4 you might decide to upgrade to a second parallel string of T-105s. As long as battery additions are only a few months apart, they won't be badly mis-balanced string to string. I would not however wait more than a year to add a second battery string.
By the time you upgrade to a second battery string, you should also plan on upgrading the solar to >1800W, so plan on getting those two extra 300W panels by that time.
So, I'd say incremental upgrades spread out over a 3 month period will get you to a completely gasoline-free solar system.
Once you get into deep winter weather, I don't know what you be facing storm-wise, so even with the upgraded solar, you might still need to run the generator occasionally when a storm blows through. What I've found though for my own system, ~2000W of solar still keeps the batteries close to full charge, even in the rain.
Work laptop: 1200Wh/day
Starlink: 1235Wh/day
Frig: 813Wh/day
TV: 120Wh/day
15" laptop: 240Wh/day
Adding up just these items I'm seeing 3600Wh/day. Let's guess and say another 400Wh for everything else. Assuming you get 5.0sunhours in June, and 2.5sunhours in December, right about now towards the equinox, you'd expect ~3.75sunhours. So, you are trying to pull 4000Wh out of a system that can't make more then ~3.75sh X 800W = 3000Wh, and a battery that only holds 105Ah X 24V = 2520Wh.
This the kind of planning you should have been doing from day 1. Like the old saying goes, you didn't plan to fail, you failed to plan.
In response to your question in post #32, of course wiring batteries in series/parallel is legitimate. It's a strategy that's been practiced for generations. Just search this site for series/parallel wiring diagrams. BUT, that is NOT what I would recommend you do. Most likely your batteries on hand are already damaged, and pairing a second set in parallel is likely to drag set 2 down the the level of set 1, so you are just throwing away more money.
You are already wasting 500$ each month for gasoline, so I think this is money better spent upgrading your system. For my own system, I hadn't used my generator in so long (2+ years) that the piston rusted in the cylinder, so I think you can use this advice.
First, get rid of the PWM controller. Buy a MPPT controller like Epever's 6415AN, which is ~320$ on Ebay right now. Buy some 72-cell grid-tie panels in the 300W range. Get two so you can you can wire them in series to get ~70VDC. That is about 150$ on Craigslist right now. That's 320$ +150$ = 470$ so you still have a bit left for some gas money.
Then re-wire your original 100W panels as 4S2P. Added together, 600W + 800W will give you 1400W, which should make you about 5.25kWh of power this time of year. Alternatively, just get two 300W panels to start, but be ready to add 2 more if it looks sorely needed.
Once you have the additional solar in place, I'd say it's time to upgrade the batteries. I would not keep adding additional strings of 105Ah batteries, assuming the first string is already going bad. 500$ from month two would get you nice 250Ah golf-carts. Trojan T-105s are ~130$, so four of them would eat up the 500$ of gas money for month 2. But, once you have the new batteries in place, you are likely to have enough power to get you through the night without dropping below 50% charge, assuming you leave the refrigerator on.
6000Wh is still not a lot of battery, but in month 3 or 4 you might decide to upgrade to a second parallel string of T-105s. As long as battery additions are only a few months apart, they won't be badly mis-balanced string to string. I would not however wait more than a year to add a second battery string.
By the time you upgrade to a second battery string, you should also plan on upgrading the solar to >1800W, so plan on getting those two extra 300W panels by that time.
So, I'd say incremental upgrades spread out over a 3 month period will get you to a completely gasoline-free solar system.
Once you get into deep winter weather, I don't know what you be facing storm-wise, so even with the upgraded solar, you might still need to run the generator occasionally when a storm blows through. What I've found though for my own system, ~2000W of solar still keeps the batteries close to full charge, even in the rain.
Doggydogworld
Solar Enthusiast
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Yes, the 2S will be 12V + 12V = 24V and the 2P will be 105Ah + 105Ah = 210Ah. Your inverter requires 24V, so as long as you use 12V batteries you'll have to stick with 2S. Any batteries you add will have to be in parallel. But NOT YET.
I did a similar exercise as @MichaelK (see below). TL:DR, before you spend a single penny on batteries, panels or controllers buy some %#$^@# meters. We keep guessing about this crap when $50 could give us actionable knowledge. Screen 6 indicates your panels are drastically under-producing. But maybe I've misinterpreted Screen 6 and they're actuall OK. Your batteries might be damaged. Or they might be fine. Your consumption might be ~5000 Wh per weekday (see below). Or more. Or less. You can't make good decisions based on guesswork.
It sounds like your generator burns ~3 gallons per night. Even at low efficiency that's 15-20 kWh of electricity. Way more than you need. With meters we could figure out how to cut that 50-75% despite your (possibly) poor panel output and (possibly) damaged batteries. Without measurements you can only throw money at the wall and hope something sticks.
Ok, good info. How do you connect the generator (the 30A/50A receptable?) Do you have a separate house battery that's active when it's connected? How do you connect the 1500W inverter? Pics would help.
Here's the first experiment I'd try. Switch to generator at 4:30pm and disconnect your solar batteries. Load up on consumption. Stick a bunch of water bottles in the freezer with airspace between them. You should already have some 5 degree F gelpacks in the freezer. Use crockpot, microwave, water, etc. as needed. At 6:30pm shut it all off. Move the frozen bottles from freezer to fridge and unplug it. Turn off the work laptop, Starlink, etc. Measure the battery voltage using your new Clamp Multimeter and consult the chart to estimate SOC. Then reconnect the battery and switch the RV to battery/inverter power. Skip Netflix and popcorn. See if your battery can carry the humidifier plus tiny loads like LED lights and phone charging all night.
If that works it should cut gas consumption by 2/3rds. You can slowly add nighttime loads, taking measurements as you do. If the batteries can't even carry the humidifier overnight they are either damaged or already at low SOC by 4:30pm. The reading you took plus additional experiments will help us figure that out.
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CONSUMPTION GUESSWORK
The biggest loads look like fridge at ~1000 Wh/day and Starlink at ~1200 (63W * 19 hours). FYI this guy converted his Gen 2 dish to run off his 12V system and cut consumption to 37W. He also avoids inverter losses, so a double win.
Do you really run the box fan only 5 hours per week? If you meant 5 hours per day that's your 3rd biggest load at 107W * 5h = 535 Wh. Otherwise the humidifier at 50W * 9h = 450 Wh is #3. Humidifier is at night, which costs you a lot more.
I figure your laptop only averages ~30W, so 300 Wh over a 10 hour workday. The full rated 120W (19.5V * 6.15A) would be intense gaming while also charging a depleted battery. I could be really wrong, though. Use your new Clamp Meter to find out for sure.
Your other loads seem to mostly be in the 100-200 Wh/day range, or on weekends (e.g. laundry) when you don't run Starlink or the work laptop.
All told it looks like ~5000 Wh per weekday. Your panels probably needs to supply 6500 Wh/day due to inefficiencies in the battery charge/discharge cycle and inverting from 24VDC to 120VAC.
With good sun your panels in theory could put out 800 W * 5 hours = 4000 Wh per day. If my guess about Screen 6 is correct they're averaging ~45 Ah * 28V = 1260 kWh per day. Your PWM controller will waste Wh, but not that many. So maybe I'm wrong about Screen 6. Or maybe something else is wrong with your panel setup. Hourly SCC readings can help us figure this out.
Doggydogworld
Solar Enthusiast
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Oh, and measure your generator fuel consumption on a typical overnight run, then measure it again for the 4:30-6:30pm run above. You can do that without buying a meter 
Point has been well taken. Working on getting a meter. Just don't know when I'll be able to get to town again. Hopefully sooner than later.
Generator has an 8 gallon tank. On nights when my wife doesn't have to work the next day, we burn about 3/4 of a tank (run time about 10-11 hours). On nights when she does work the next day and gets up early, we burn about a half tank (run time about 6-7 hours).
I connect the 5th wheel's power cord to the generator when needed, as if I were hooking up to on-grid power (Predator 6500W peak/5500W running). I have a 4-prong NEMA adapter for that. Then during the day, I have a 3-prong adapter that I use when hooking the 5th wheel's power cord to the solar inverter.
Yes, I already know I'm going to catch major flack for how I have my panels set up right now. As stated in an earlier poet, I should have the money in a week or so to buy the materials to build a frame to get them all at the same angle and off the ground.
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Yeah, that part where he says, "this is not for the faint hearted...", that's me. I am horrible at anything electrical, unless it's super basic. This solar stuff is about as deep as I have ever delved into electrical and it's been nail-biting for me since the start. Don't know why it's a phobia, but it is, lol! If I screwed something up on my Starlink by trying to convert it to 12v, it'd be bad as we don't have the extra money to buy a new cable and it would take to long to get it to us and both my wife and I would miss hours or even days from work. Not good.
Right now, we don't use it at all because the temps are very comfortable. When it was hotter a few weeks back, we did use it a lot more. I must not have been thinking accurately when I typed that estimate though. I'd say averaging it out, probably 3-4 hours a day sounds about right.
I don't do any gaming on it, but I do run a number of programs throughout the work day. On cloudy days, I have unplugged my laptop power to try and let the solar have a little more gain, but my battery only lasts about an hour or so before have to plug it back in. Not sure if it's better to just leave it plugged in the entire time or unplug it and let it charge back up.
And on that same subject, due to the short battery life, my company bought me a brand new 13" Dell laptop. I will hopefully have that set up this week and I'm hoping the battery will last a lot longer so I can run just off the battery most of the day.
Currently the sun hits my panels by about 9:30am and have full sun by just after 10am. Direct overhead sun is around noon to 1pm. Sun is setting around 6:26pm but is off the panels by around 6pm.
I think you may have been right in your second theory about screen 6. I think it might be cumulative. I multiplied 45 Ah/day * the approximate days we've been living off-grid and using the solar and it came out to something like 2086 Ah.
We do our best to not kick the generator on until as late as possible. It varies depending on our power needs for the day and when the solar kicks off. On average, we probably start the generator between 7pm and 8:30pm. Which means a lot of times, we go without solar and generator for a couple hours a day and just have the RV's 12v battery to run lights, roof fans, and range hood.Oh, and measure your generator fuel consumption on a typical overnight run, then measure it again for the 4:30-6:30pm run above. You can do that without buying a meter
I hear you. My planning was lacking but as I told my wife (who is more than just a little upset with me over this), I truly believed I was doing the research I needed. There were just so many questions I DIDN'T know to ask. I watched a bunch of videos and also believed the solar "kits" Eco-Worthy had put together would be sufficient (i.e., "Off-grid Cabin Solar Kit Set-up). The other problem I ran into was just so many conflicting information from one person or video to another. For example, just last night. We decided to not run the generator overnight and used the frozen water jug plan for the fridge (which worked out, btw). But, we both need background noise to sleep (like white noise or a fan or humidifier) so we decided to leave the bathroom roof fan on. I read easily 6 different threads and websites to see how long a 12v deep cycle battery would run one of these little fans and got at least half that in different answers. Anywhere from 5 hours to 50 hours are the answers I found. The fan was running on super low speed by the time I woke up at 6am and the one LED light we left on was dim by about 50% of normal.
How is a greenie like me supposed to decipher what is fact and what is BS with all the conflicting info out there?
I like and agree with the plan above and will move on getting more and better panels and charge controller and eventually batteries, but it's definitely easier said then done. The $500 we're spending on gas for the generator right now is not even really in the budget so we've been robbing Peter to pay Paul, so to speak. But I'll see how we can rework the budget to try and meet some of these goals. Thank you!!
Doggydogworld
Solar Enthusiast
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OK, the pic helps. Interesting math on Screen 6, too. So as I see it:
1. You can either use your generator as faux "shore power" OR ...
2. You can use Solar/Battery/Inverter as faux "shore power" OR ...
3. You can disconnect both and run off your 5th wheel's internal 12V battery
Did I get that right? Are your 5th Wheel's 120V outlets live in case #3? Will the microwave run?
Right now it seems your battery starts draining by 4:00-4:30 as the sun angle gets low. Your consumption is still high at that point, so it drains quickly. If you use the generator during those high demand hours and save the battery for the low overnight loads, you can cut gasoline consumption by half. And if you can compress your evening loads into an even shorter window, e.g. ~2 hours, you can cut gas burn even more.
At least that's the theory. You'll have to test it.
Of course long term you want to stop using the generator at all, except during bad cloudy stretches. But if I'm right you can slash your fuel bill immediately, before you buy more equipment. This buys you time to figure out why your panels only seem to produce 45 Ah (1260 Wh) per day plus other things you should know before spending money.
In other notes, I wouldn't unplug the laptop. You can measure actual consumption once you have a meter. At some point I'd like to connect your solar batteries to your 5th wheel's 12V panel and shift loads to DC. But that's fine tuning. Right now you need to focus on gas consumption and panel output.
Here are the 5 degF freezer packs:
Your freezer must reach 0 degF to freeze them, and it takes a while. But they'll hold your unplugged freezer near 5 degF for many hours. Regular ice or 33.8 degF gel packs don't kick in until temps exceed 32 degF. That's OK for the fridge side, but will ruin your frozen food.
I wouldn't try the Starlink hack, either. Just thought it was interesting.
Try to get those hourly SCC readings. Every hour from 9am-6pm would be even better. Right now it's the only "meter" you have. But it might be enough to help solve the panel mystery.
1. You can either use your generator as faux "shore power" OR ...
2. You can use Solar/Battery/Inverter as faux "shore power" OR ...
3. You can disconnect both and run off your 5th wheel's internal 12V battery
Did I get that right? Are your 5th Wheel's 120V outlets live in case #3? Will the microwave run?
My theory is your generator burns almost as much gas generating 100W as it would at 2500W. I've seen tests of this, but don't have links handy. Your battery is the opposite. It costs 25x as much to drain it at 2500W as at only. So you want to use battery for long duration low loads.
Right now it seems your battery starts draining by 4:00-4:30 as the sun angle gets low. Your consumption is still high at that point, so it drains quickly. If you use the generator during those high demand hours and save the battery for the low overnight loads, you can cut gasoline consumption by half. And if you can compress your evening loads into an even shorter window, e.g. ~2 hours, you can cut gas burn even more.
At least that's the theory. You'll have to test it.
Of course long term you want to stop using the generator at all, except during bad cloudy stretches. But if I'm right you can slash your fuel bill immediately, before you buy more equipment. This buys you time to figure out why your panels only seem to produce 45 Ah (1260 Wh) per day plus other things you should know before spending money.
In other notes, I wouldn't unplug the laptop. You can measure actual consumption once you have a meter. At some point I'd like to connect your solar batteries to your 5th wheel's 12V panel and shift loads to DC. But that's fine tuning. Right now you need to focus on gas consumption and panel output.
Here are the 5 degF freezer packs:
Arctic Ice Tundra Series Lunch Box Size Freezer Pack (Plus 5-Degree F) 1201 - The Home Depot
Arctic Ice Tundra Series has a very unique freezing point of 5°F and is designed to help maintain a consistent freezer temperature in coolers. While not as cold as dry ice, Arctic Ice Tundra Series can
www.homedepot.com
I wouldn't try the Starlink hack, either. Just thought it was interesting.
Try to get those hourly SCC readings. Every hour from 9am-6pm would be even better. Right now it's the only "meter" you have. But it might be enough to help solve the panel mystery.
MichaelK
Solar Wizard
Looking at the panel pic in post #36, I see part of your problem is half of the panels are more or less laying almost flat on the ground. That's guaranteed to cut production by maybe 25-30%. Yes, get the panels off the ground asap, and oriented towards the sun. The way things are right now, I'm not expecting that you are getting more than 500W out of those panels.
What kind of area are you living in now? Semi-rural, semi-suburban, way out in the mountains? I'd be walking around on garbage day and looking for anything I could use to make a panel frame. Some scrap lumber, an old bed frame, a trashed door, anything. Is there a local flea market on the weekends that you can cruise through? At my local FM, I see angle-iron, unistruts, and other metal stuff sold cheap. I got a clamp meter there for 10$ and a KillaWatt for 5$. Just get the panels off the ground and oriented towards the sun. You should see an immediate improvement once the panels really face the sun.
Can you give us you general location? Just what region of what state you live in. We can help you shop on Craigslist for some of the things you need. I've purchased my best panels off of Craigslist, and also got most of the steel I used to make my solar frames. I've gotten 10' lengths of unistrut for a little as 5$ each. Here's a pic of one of the solar frames I built with them. Just one frame holds 1000W of panels. I agree with DDW about instrumentation, and solving your basic problems before getting more batteries.
As I mentioned in post #33, solve the basic problems and add more solar BEFORE spending money on more batteries. One of the critical weaknesses of lead-acid batteries is they die young with weak charging. So, up the solar first.
Here is the order I would get things done....
1) Build a proper frame to hold the panels up to the light.
2) Buy additional grid-tie panels. Don't waste money on more 100Wers
3) Replace the PWM controller with a MPPT.
4) Replace the 105Ah batteries with 210-250Ah golf-carts. Don't add additional 105Ah batteries to what you already have. Turn them in for core-charges.
5) Add additional grid-tie panels of the same wattage/voltage
6) Add another 24V string of golf-carts
7) Consider a higher-quality inverter. I've got a Schneider Conext 4024 that is wonderful. It handles power tools well, produces split-phase 120/240VAC, and has built-in generator charging circuit. You plug your generator directly into socket for ACin on the inverter, and it converts the generator AC into up to 90A of DC charging current for the batteries.
What kind of area are you living in now? Semi-rural, semi-suburban, way out in the mountains? I'd be walking around on garbage day and looking for anything I could use to make a panel frame. Some scrap lumber, an old bed frame, a trashed door, anything. Is there a local flea market on the weekends that you can cruise through? At my local FM, I see angle-iron, unistruts, and other metal stuff sold cheap. I got a clamp meter there for 10$ and a KillaWatt for 5$. Just get the panels off the ground and oriented towards the sun. You should see an immediate improvement once the panels really face the sun.
Can you give us you general location? Just what region of what state you live in. We can help you shop on Craigslist for some of the things you need. I've purchased my best panels off of Craigslist, and also got most of the steel I used to make my solar frames. I've gotten 10' lengths of unistrut for a little as 5$ each. Here's a pic of one of the solar frames I built with them. Just one frame holds 1000W of panels. I agree with DDW about instrumentation, and solving your basic problems before getting more batteries.
As I mentioned in post #33, solve the basic problems and add more solar BEFORE spending money on more batteries. One of the critical weaknesses of lead-acid batteries is they die young with weak charging. So, up the solar first.
Here is the order I would get things done....
1) Build a proper frame to hold the panels up to the light.
2) Buy additional grid-tie panels. Don't waste money on more 100Wers
3) Replace the PWM controller with a MPPT.
4) Replace the 105Ah batteries with 210-250Ah golf-carts. Don't add additional 105Ah batteries to what you already have. Turn them in for core-charges.
5) Add additional grid-tie panels of the same wattage/voltage
6) Add another 24V string of golf-carts
7) Consider a higher-quality inverter. I've got a Schneider Conext 4024 that is wonderful. It handles power tools well, produces split-phase 120/240VAC, and has built-in generator charging circuit. You plug your generator directly into socket for ACin on the inverter, and it converts the generator AC into up to 90A of DC charging current for the batteries.
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Doggydogworld
Solar Enthusiast
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- Aug 29, 2022
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Those are some awesome solar frames!
@Josh M. - This guy runs everything including a 5k BTU A/C on 1185W of panels. 750W are flat-mounted, too.
Kinda long, and a few years old so equipment is outdated, but good general info. Didn't say how many kWh of batteries, but they weigh 457 lbs so I'm guessing 5-7 kWh. He really babies them, they'd already lasted 6 years and were still going strong. Most AGMs die after 1-2 years of heavy daily cycling. He shifted most usage to daytime so he doesn't discharge heavily overnight.
@Josh M. - This guy runs everything including a 5k BTU A/C on 1185W of panels. 750W are flat-mounted, too.
Kinda long, and a few years old so equipment is outdated, but good general info. Didn't say how many kWh of batteries, but they weigh 457 lbs so I'm guessing 5-7 kWh. He really babies them, they'd already lasted 6 years and were still going strong. Most AGMs die after 1-2 years of heavy daily cycling. He shifted most usage to daytime so he doesn't discharge heavily overnight.
Correct. However, the 120V outlets are dead without shore power. The only things that run on the 12V are the LED lights, range hood fan and light, the furnace, and the bath fans. Micro and fridge are strictly 120V (shore power). I looked it up and not all RV's are configured with a control panel that has a 12 V converter to run the 120V outlets. Mine does not appear to have one. It's a 1994 Jayco 35' 5th wheel.
Work has been way overly busy since I last logged on so I haven't been able to get the hourly readings, plus, we had 3 days straight of heavy clouds and rain. I should be able to get the readings next week.My theory is your generator burns almost as much gas generating 100W as it would at 2500W. I've seen tests of this, but don't have links handy. Your battery is the opposite. It costs 25x as much to drain it at 2500W as at only. So you want to use battery for long duration low loads.
Right now it seems your battery starts draining by 4:00-4:30 as the sun angle gets low. Your consumption is still high at that point, so it drains quickly. If you use the generator during those high demand hours and save the battery for the low overnight loads, you can cut gasoline consumption by half. And if you can compress your evening loads into an even shorter window, e.g. ~2 hours, you can cut gas burn even more.
At least that's the theory. You'll have to test it.
Of course long term you want to stop using the generator at all, except during bad cloudy stretches. But if I'm right you can slash your fuel bill immediately, before you buy more equipment. This buys you time to figure out why your panels only seem to produce 45 Ah (1260 Wh) per day plus other things you should know before spending money.
In other notes, I wouldn't unplug the laptop. You can measure actual consumption once you have a meter. At some point I'd like to connect your solar batteries to your 5th wheel's 12V panel and shift loads to DC. But that's fine tuning. Right now you need to focus on gas consumption and panel output.
Here are the 5 degF freezer packs:
Your freezer must reach 0 degF to freeze them, and it takes a while. But they'll hold your unplugged freezer near 5 degF for many hours. Regular ice or 33.8 degF gel packs don't kick in until temps exceed 32 degF. That's OK for the fridge side, but will ruin your frozen food.Arctic Ice Tundra Series Lunch Box Size Freezer Pack (Plus 5-Degree F) 1201 - The Home Depot
Arctic Ice Tundra Series has a very unique freezing point of 5°F and is designed to help maintain a consistent freezer temperature in coolers. While not as cold as dry ice, Arctic Ice Tundra Series canwww.homedepot.com
I wouldn't try the Starlink hack, either. Just thought it was interesting.
Try to get those hourly SCC readings. Every hour from 9am-6pm would be even better. Right now it's the only "meter" you have. But it might be enough to help solve the panel mystery.
On a side note, I haven't been able to build a frame for the panels yet, but I did at least get them all at the same angle and it seems to have made a difference. I noted that previously, the mid-day reading for juice from the panels to the batteries was around high 27-ish volts at the peak of the day to 28.5V. Since the re-angling of the panels to be all the same angle, I'm consistently seeing 29.3V to 29.7.
I also started unplugging my Starlink as soon as I get done with work at 4:30pm and just use our data for cell phone use if we want to get online. That alone has prolonged the amount of time until the solar goes dead by a solid hour (not impressive, but it's an improvement). That extra time allows us to shower before the solar runs out (another adjustment for us, as we normally shower just before bet which is typically very late). At night, we have stopped running the generator all together because we just cant afford the gas. We only run it in the morning for about 4 hours when I get up and start work at 6am, until the sun hits the panels. So, we have 3 one gallon water jugs frozen solid and drop them in the fridge overnight. That is working out well as far as keeping the fridge plenty cold over night.
And to answer an earlier question (not sure who asked), I live in Northern Arizona on 2 1/4 acres about 30 minutes NW of Williams. No utilities, no well. The closest neighbor and there aren't many, is about a half mile away so we're fairly rural. Sunrise 6:18am, sunset 6:25pm. Sun is off the panels completely by around 5:45pm but the suns position vs. panel position is dramatically reduced by around 4:30 to 5pm. Once I have a frame for the panels, I'll be able to adjust them to follow the suns path better.
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Just answered a couple of these questions in my latest post to DDW.
We live pretty rural. There's trash service but in the month and a half we have been out here, I haven't seen anyone put anything out on the "curb" (there's not actually a curb, just dirt roads, lol!) except basic refuse in cans. I still keep my eye open though, just in case.
Also, because of how rural we live, selling my batteries on something like Craigslist or OfferUp is a crap-shoot at best. I also have a second 60W PWM charge controller that Eco-Worthy sent me by mistake, that I could probably list and ship since it's small, but since it's only $80 bucks brand new, not sure I'd get enough to make it worth the effort.
I like your plan for sure and will use it to move forward. #1 will be done within the next week to week and a half. #2 will probably not happen for about a month. #3 - can you suggest an MPPT controller that would handle say, 250W to 310W panels, that won't break the bank? I'd like to get my PV array up from 800W to about 1500W+. My current PWM says it will handle up to 1800W on a 24V battery bank. And when adding panels, can I just add the 250W or 310W grid-tie panels to my existing 8 100W panels or is the configuration wrong?
Doggydogworld
Solar Enthusiast
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- Aug 29, 2022
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That's good news on the panels. Do you get more than 45 Ah per day now?
If you shade one of two panels in series you basically lose both. Even partial shade of one panel can do it, depending on how it's wired. Same if one panel is angled poorly -- it degrades output from both. This is less of an issue with parallel (but parallel has other issues).
AZ is a decent place to buy used solar. These panels in Kingman aren't a killer deal, just an example. Three of the 230W panels would cost you $225 to get to 1490W. Except it's tricky to mix and match panels. Vmp* for your panels is 18V vs. about 30V for those in Kingman. With an MPPT rated for 150V you could put 3 Kingman panels in series (90V) and parallel them with a string of five of your 100W ones (also 90V). But that leaves 3 leftover 100W panels. Not good. So only 1190W. Better to find used panels with Vmp=36V and run at 72V. And maybe save money by using a 100V MPPT.
This guy in Flagstaff has lots of used stuff and might help you troubleshoot/optimize things.
Better deals in Phoenix, if you're patient.
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Vmp - Voltage for Max Power. At full sun, 25 degF, etc. It goes down as your panels hotter, is higher when they're cold.
Voc - Voltage at Open Circuit (no current flowing). 20% or so higher than Vmp. Easy to measure. Also varies with temp. Don't let Voc exceed MPPT rating, even on the coldest morning.
If you shade one of two panels in series you basically lose both. Even partial shade of one panel can do it, depending on how it's wired. Same if one panel is angled poorly -- it degrades output from both. This is less of an issue with parallel (but parallel has other issues).
AZ is a decent place to buy used solar. These panels in Kingman aren't a killer deal, just an example. Three of the 230W panels would cost you $225 to get to 1490W. Except it's tricky to mix and match panels. Vmp* for your panels is 18V vs. about 30V for those in Kingman. With an MPPT rated for 150V you could put 3 Kingman panels in series (90V) and parallel them with a string of five of your 100W ones (also 90V). But that leaves 3 leftover 100W panels. Not good. So only 1190W. Better to find used panels with Vmp=36V and run at 72V. And maybe save money by using a 100V MPPT.
This guy in Flagstaff has lots of used stuff and might help you troubleshoot/optimize things.
Better deals in Phoenix, if you're patient.
----------------------------
Vmp - Voltage for Max Power. At full sun, 25 degF, etc. It goes down as your panels hotter, is higher when they're cold.
Voc - Voltage at Open Circuit (no current flowing). 20% or so higher than Vmp. Easy to measure. Also varies with temp. Don't let Voc exceed MPPT rating, even on the coldest morning.
I believe so, but don't know exactly how much more. Estimating I'm getting more along the lines if near 65-70 Ah per day. But likeI said, the past few days were extremely cloudy and no direct sun, so it could be more than that. This coming next week and a half is forecasting mostly to full sunny days so I should get a solid reading and estimate from that.
Yeah, I have heard that. And I actually just chopped down a tree this morning that was shading 1 1/2 panels in the early morning sun. As soon as I had it down, I watched the reading on S1 climb by a full volt and a half.
I did a little looking and there are a few places in AZ that sell good used panels at decent prices and better, they actually offer shipping as well. Thanks for the links. I'm very likely gonna hit the guy in Flagstaff up. That's only about 45 minutes from me and my step-daughter goes to college there so we visit from time to time.
So, your comment about colder temps affect on my system. So, it's not just the lack of sunlight hours that reduces solar performance? It's also cold temps? What am I in for when winter hits outside of shorter days?? Sorry for such a newb question. Again, just trying to figure this all out and prepare.
Doggydogworld
Solar Enthusiast
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Cold temps boost Vmp, which can help system performance a little. Not enough to offset the lower winter sun angle and shorter days, unfortunately. And you probably need MPPT to see any benefit from higher voltage. The PVWatts web page gives good estimates of seasonal variation at your exact location. You can play around with panel angle and stuff, too.
Cold temps also boost Voc, which can be a problem. Say you have two 45Voc panels in series for 90V and a MPPT rated for 100V max. So far, so good. But that's at 25 deg C. Every 3 deg C drop boosts your system Voc by roughly 1V. So at -5C you hit your 100V limit. Any colder than that can damage your MPPT.
Be careful shipping just a few panels. It's pretty easy to damage them. Full pallets usually come through OK if you want to get really serious about expansion
MichaelK
Solar Wizard
Go back to post # 33 and re-read. Every single question you're asking was already answered in post 33
Sorry it's taken me so long to respond. Things have been a bit hectic with work.Cold temps boost Vmp, which can help system performance a little. Not enough to offset the lower winter sun angle and shorter days, unfortunately. And you probably need MPPT to see any benefit from higher voltage. The PVWatts web page gives good estimates of seasonal variation at your exact location. You can play around with panel angle and stuff, too.
Cold temps also boost Voc, which can be a problem. Say you have two 45Voc panels in series for 90V and a MPPT rated for 100V max. So far, so good. But that's at 25 deg C. Every 3 deg C drop boosts your system Voc by roughly 1V. So at -5C you hit your 100V limit. Any colder than that can damage your MPPT.
Be careful shipping just a few panels. It's pretty easy to damage them. Full pallets usually come through OK if you want to get really serious about expansion
Anyhow, thanks for the explanation. That helps a bunch.
Update...
Though I haven't built the frame for my panels yet (should be next week), I have moved and repositioned my pv array. All 8 panels are sitting at the same angle and I am capturing at least 2 additional hours of sunlight a day by moving them. I have also removed 2 more trees that I noticed were partially shading a few panels in the early morning. With this change, my S1 is consistently showing 29V to 29.26V under load for a good majority of the day. We have made a few lifestyle adjustments, which I think I mentioned in a previous post that has helped extend how long the solar is lasting. Unplugging my internet immediately after work, keeping 1 or 2 frozen 1-gallon jugs in the fridge during the day (seems to keep it from running quite as often), etc., seems to be helping. Even with some pretty heavily clouded days this week, the solar is lasting until around 9pm and on full sun days it's lasting until around 11:30pm.
I contacted the guy in Flagstaff you gave me the link for and he has already contacted me back with a few suggestions until I can buy some panels and an MPPT controller form him. He seems to be willing to help with more than just selling his items. Thanks for that.
I'll post more updates hopefully soon. Thanks again for all the help and patience with my lack of knowledge here!!
Oh, forgot to ask. I am getting some conflicting information as to the cable length I can use between my panels and combiner box. The cables that came with the kit I bought are 16.4' 12AWG cables (w/MC4 connectors). Ideally I would like to buy another set of the 16.4' cables to get my panels out in to an open area where they won't get shaded ever. But I am gathering that I need a heavier gauge cable to go beyond the current 16.4' distance. The conflicting info I am getting is in regard to the gauge I need to be the 33' or so from my combiner box. So, my question is 2-fold;
1. What gauge do I actually need for that distance?
2. Would doubling the distance between panels and combiner be a smart move, given I get the correct gauge cable?
1. What gauge do I actually need for that distance?
2. Would doubling the distance between panels and combiner be a smart move, given I get the correct gauge cable?
MichaelK
Solar Wizard
Here is a link to a handy voltage drop calculator that I use.
www.calculator.net
Plugging in your specifications, I see this.....
It appears that you are only loosing 1V at that distance, which is probably OK until you get your MPPT controller. Then you can wire more panels in series to reduce voltage drop more.
Keep in mind that the better controllers have higher voltage limits, so If you can stomach the extra money, a higher quality controller with a 200V limit (Epever 5420AN) will allow you to run strings of up to 4 grid-tie panels for hundreds of feet. Right now, I'm funneling 8A through 10 gauge wire at 120VDC for 130' without any measureable voltage drop. Then you'll have the liberty to place your arrays just about anywhere you want, which is likely to increase overall production even more.
Voltage Drop Calculator
This free voltage drop calculator estimates the voltage drop of an electrical circuit based on the wire size, distance, and anticipated load current.
www.calculator.net
Plugging in your specifications, I see this.....
It appears that you are only loosing 1V at that distance, which is probably OK until you get your MPPT controller. Then you can wire more panels in series to reduce voltage drop more.
Keep in mind that the better controllers have higher voltage limits, so If you can stomach the extra money, a higher quality controller with a 200V limit (Epever 5420AN) will allow you to run strings of up to 4 grid-tie panels for hundreds of feet. Right now, I'm funneling 8A through 10 gauge wire at 120VDC for 130' without any measureable voltage drop. Then you'll have the liberty to place your arrays just about anywhere you want, which is likely to increase overall production even more.
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