Criticism/suggestions requested on new Full-timer RV Solar Setup
![Drauku](https://wb.vanillicon.com/bee24ed47cd24ebc97710b04abb1cf1b_100.png)
250 W Watt Poly Panel 24V (solartec)
6
Solar Odyssey 2000W/24V Pure sine wave Inverter/Charger
1
Solar Odyssey 50A MPPT Controller
1
PV Wire 10 AWG 600V UL Class [100 feet ]
100
Z Brackets Mounting System
6
12V AGM Batteries @100AH X 6
6
Y Branch Connectors
2
15 A Fuses With Holder
6
10 Pair MC4 Connecter
1
I will be picking up battery wire from a separate vendor, along with connectors for the battery terminals.
My plan is to wire the 6 panels in parallel with a 15A fuse per panel into the charge controller, then to the batteries in parallel (wired per suggestions at http://www.smartgauge.co.uk/batt_con.html thanks to Apples on this forum). The batteries are then wired with a ??A fuse (not sure how to determine the Amps needed for this fuse) to the Inverter input, and the Inverter output goes to my RV converter/main RV power. Additionally, this Inverter can also act as a generator/shore power charger for the battery bank, so I will wire the shore power into the charger-in on the Inverter.
As an aside, is there a way to get my Air Conditioner to run on the batteries? I know it will use up a lot of my power, but sometimes I will need to let it run to keep the cat temperate while we are away for short trips.
Any suggestions would be greatly appreciated. I plan on buying this list in the next couple days unless there are some huge change suggestions. Thanks in advance!
Comments
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Hello all! Thanks in advance for any suggestions you might have regarding this project. I'm living full-time in a 32' 5th wheel with my wife and two daughters and a cat. We want to convert our coach to allow for 100% off-grid use, and here's my beginners attempt at a setup that will 'start' to satisfy that goal.
250 W Watt Poly Panel 24V (solartec)
6
Solar Odyssey 2000W/24V Pure sine wave Inverter/Charger
1
Solar Odyssey 50A MPPT Controller
1
PV Wire 10 AWG 600V UL Class [100 feet ]
100
Z Brackets Mounting System
6
12V AGM Batteries @100AH X 6
6
Y Branch Connectors
2
15 A Fuses With Holder
6
10 Pair MC4 Connecter
1
I will be picking up battery wire from a separate vendor, along with connectors for the battery terminals.
My plan is to wire the 6 panels in parallel with a 15A fuse per panel into the charge controller, then to the batteries in parallel (wired per suggestions at http://www.smartgauge.co.uk/batt_con.html thanks to Apples on this forum). The batteries are then wired with a ??A fuse (not sure how to determine the Amps needed for this fuse) to the Inverter input, and the Inverter output goes to my RV converter/main RV power. Additionally, this Inverter can also act as a generator/shore power charger for the battery bank, so I will wire the shore power into the charger-in on the Inverter.
As an aside, is there a way to get my Air Conditioner to run on the batteries? I know it will use up a lot of my power, but sometimes I will need to let it run to keep the cat temperate while we are away for short trips.
Any suggestions would be greatly appreciated. I plan on buying this list in the next couple days unless there are some huge change suggestions. Thanks in advance!
You would be better off with 4 6V batteries in series than 6 12v batteries. You will avoid parallel connections and simplify wiring. Concorde SunXtender makes some fine AGMs. You will probably need a very efficient AC unit to run off of batteries and a bigger battery bank. That being said, you should start by adding up all your loads before you design your system to make sure it is balanced. -
Thanks Ikruper, would you mind expanding on why 4x 6V batteries would be better than 6x 12V? I was looking into doing that, but thought I would have to use 2x the number of batteries to maintain the 600Ah I would need for a days' use.
Also, would I have to get a different Inverter than the current 24V model I have listed? -
As Ikruper pointed out, avoid parallel batteries. Ikruper mentioned that it would simplify wiring, which is true, but there are many more important reasons to do so. The smartgauge site shows you how to parallel batteries if you must do so, but does not explain why parallel batteries are so problematic. Also, the battery bank you describe is 300 ah at 24 volts, not 600 ah.
What are the specs on your solar panels (Vmp and Imp)? Many so-called "24 volt" panels will not properly charge a 24 volt battery.
I do not see a combiner in your equipment list. You will need one and I suggest you use circuit breakers rather than fuses.
What's with the "15 amp fuses with holder"? Where do they fit in?
Finally, there is the issue of grounding.... if your power distribution panel has neutral bonded to ground, there will be issues when you connect to shore power because your shore power will also have a neutral-ground bond. You may need a special transfer switch for shore power, rather than just counting on the built in transfer of your inverter.
--vtMaps4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i -
Thanks Ikruper, would you mind expanding on why 4x 6V batteries would be better than 6x 12V? I was looking into doing that, but thought I would have to use 2x the number of batteries to maintain the 600Ah I would need for a days' use.
Also, would I have to get a different Inverter than the current 24V model I have listed?
Vtmaps gives good advice. Parallel battery banks can be difficult to maintain because they can become unbalanced. This is a somewhat controversial issue, but most will agree that the potential exists to cause one bank to suffer because of imbalance during charging or discharging. Think of two water towers sitting next to each other with a 12" pipe connecting them. Water pressure will equilibrate but there is potential for two different pressures. Add another tank and it gets even more complicated. Putting two batteries (ie water towers) in series effectively makes one water tower that is twice the capacity. Each battery gets charged and discharged the same.
Your system is further hindered using AGM batteries because you cannot measure the specific gravity of the cells and thus easily detect and remedy this sort of situation.
The issue of AH of a battery and 12v vs 24v can be confusing. If you take two 6v batteries each with 225 AH capacity and put them in series you get 12v but still at 225 AH. Don't worry, that is still twice as much power. If you take the same two 6v batteries and put them in parallel you get 6v at 450 AH, the same amount of power stored. An advantage of using 6v batteries instead of 12v is that they have more lead and thus are more robust.
Also, before you go out and purchase 4 6v batteries, please add up all your loads. Get a total that you would use all at one time and also calculate based on hours of usage what your total daily requirements will be. If you get your batteries and then load them up, it is very difficult to expand an existing system and keep things balanced. You also should not add more new batteries to existing old batteries, even in series, because then you get similar problems to a badly designed parallel bank.
And, since you specify 100% off-grid use, I am assuming you are not going to be at an RV site with shore power. You will need a generator for cloudy days, for the winter when you have less solar and most likely even in the summer because it is very hard to get enough hours of sun to fully charge a battery bank in 4-5 hours.
You have not identified the batteries you will be getting. All AGM batteries are not equal in performance or quality. Whatever you select, read and re-read the technical manual for their recommendations on charging and discharging. Select your charger (you will need one) and your charge controller based on their recommendations. AGM batteries can be charged faster than flooded batteries, and you will want to make sure they are fully charged after each cycle.
I don't see how you can possibly plan all of this in the next couple days. Take your time because it is complicated to get all these pieces to work together for your specific needs, and if you make a mistake you will likely have hardware you cannot use.
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I think it is premature to select an inverter until you have scoped out your loads. Also, I could not find that brand with a google search to look at its specs.
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Agree with the others... slow down. Dont buy anything yet. I know the excitement can get the better of us at these times, but with RE the devil is in the detail, and your list suggests you havent done enough planning yet.
One's resource constraints dictate the basis of the design. Among these are:
a. demand requirement
b. solar resource
c. roof space
d. budget
All designs start with those. On an RV we assume:
a. is low to moderate (dont go expecting to run too much),
b. is not ideal (flat roof, shading,and variable by location),
c. is especially tight (conflicts with vents, antennas etc), and
d. is usually not an issue (power budget small percent of RV investment).
Thus for RVs, one approach is to max out the roof space, and work backwards to what that will power. Using that approach it can pay to spend the money on high efficiency panels. (more power per roof space). Mounting and combiner needs special thought. You want to minimize penetrations yet combiner is better inside (more accessible, weather tight). Charge controller... use a name brand. Stick with the big players, Midnite, Morningstar etc (peice of mind on the road).
If you can confirm that approach then we can do some math to size the battery, inverter and BOS. Then we can ponder any shortfall between demand and supply, and size/brand of genset, inverter etc.
1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar -
As Zoneblue says, one approach that works well for RVs is to simply have the most panels that will fit! When have you ever heard an RVer complain that they have too much solar power, or too much anything for that matter? Fill your roof with panels, then you'll never wish you'd put more there!
More seriously though. that Solar Odyssey company makes me nervous. Several of their installations seem to have very noticeable shading on the panels they installed - any company that installs panels that are shaded to that extent may not be a company with whom you want to spend your hard-earned cash? Instead of some company-named products like panels and electronics, use accepted brands such as any good home installation would prefer, such as the products sold through NAWS.
However you decide to secure your panels, just remember that they're subject to the equivalent of a mild hurricane every time you drive down the road at 60 MPH. Mounts must be absolutely secure and weather-tight. Do not rely on caulk to seal things: it always deteriorates over time, then water will come in and cause major problems.
John40' Crown bus with 2kW of tiltable panels on the roof:
Eight Sharp 255W, two Morningstar TS-MPPT-60, Magnum MS2000, Champion C46540 generator converted to propane, eight golfcart batteries, and maybe a small Exeltech inverter for the fridger.
Southern California
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Solar is a part of a balanced system of knowing your needs and wants, conserving without sacrifice, having enough battery to cover those when the sun doesn't play nice, enough panel to bring those batteries up relatively quickly when it does and a back up means of charging for when it hides too long. Weather conditions, location, time of year are all factors, plan for the worse.
Or you can cover the roof and fill the battery bay and learn to live with what you have.
Our 750w system is small compared to some, but for our usage it appears to be huge. It also seems like we are carrying a lot of useless weight having 675 Ah in battery. Both would be true if Sunny Colorado was actually sunny. I get sun from sun up to noonish most days and then clouds for the rest of the day as the weather builds over the peaks. So I designed the system to at least keep us going when it's cloudy or in the shorter days of winter. When it is sunny it's oh baby let the good times roll as we can use the system for A/C, cooking and hot water, most of the time we are more conservative.
Our batteries are three Lifeline AGM 8-D's because they fit where I needed them too and getting a good deal doesn't hurt either. Believe it or not our system is just big enough to hit the minimal charge rate for one of them. They can gobble up a enormous amount of amps and actually can need it to get the battery stirred up, so at times I will not only single out one battery but add a 36a power supply and even the converter up to it's voltage limit for around 140a if I need to top charge or condition on a extended trip. Luckily all of that type of charging has been at home and on the grid so far.
So the balance needed isn't just numbers to be filled out but a combination of things including making sure the equipment plays well together. (AGM's can require high charging voltages, can that controller supply them?)
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Assuming you are powering 12 volt systems in an RV you may be overloading your 50 amp charge controller with 1500 watts of solar power stepped down by the MPPT CC to a 12 volt nominal voltage. That being said your inverter nominal would need to be 12 volt as well.
2.1 Kw Suntech 175 mono, Classic 200, Trace SW 4024 ( 15 years old but brand new out of sealed factory box Jan. 2015), Bogart Tri-metric, 460 Ah. 24 volt LiFePo4 battery bank. Plenty of Baja Sea of Cortez sunshine.
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Warning! Monster post here... sorry!
Thank you all for your informative inputs! I had done a lot of research before I stumbled on that Solar Odyssey company, and thought it might be a bit "too good" for the options they offered, particularly since they didn't offer any specifications on their website for the products offered.
Apparently my research over the past couple months wasn’t very effective… I seem to have missed quite a bit.
Here is a chart I cobbled together of our estimated daily usage requirements:
Appliance
volts (V)
amps (A)
watts (W)
daily use (min.)
Amp Hour (A·h)
Refridgerator
120V
6.25A
750W
1440
1500
Laptops (x4) (charge)
120V
6.00A
720W
480
480
Breadmaker
120V
5.00A
600W
210
175
Modem LTE
120V
0.80A
96W
960
128
Router E3000
120V
0.80A
96W
960
128
Pressure Cooker
120V
8.33A
1000W
60
83
Grill Electric
120V
5.00A
600W
60
50
Fans (x2)
120V
0.83A
100W
360
50
Microwave
120V
12.50A
1500W
15
31
Popcorn Popper
120V
12.00A
1440W
10
20
Stereo / Surround
120V
0.50A
60W
240
20
Blender
120V
11.50A
1380W
10
19
Toaster
120V
6.25A
750W
10
10
Tablets (Sony x2) (charge)
120V
1.00A
120W
60
10
Phones (x2) (charge)
120V
1.00A
120W
60
10
Waffle Maker
120V
1.83A
220W
30
9
Tablets (Xoom x2) (charge)
120V
0.60A
72W
60
6
Dyson Vacuum (charge)
120V
0.30A
36W
10
1
Space Heater (x2)
120V
12.50A
1500W
0
0
A/C
120V
9.17A
1100W
0
0
Appliance
volts (V)
amps (A)
watts (W)
daily use (min.)
Amp Hour (A·h)
Hot water heater
12V
41.67A
500W
260
181
Vent Fans (x2)
12V
2.00A
24W
480
16
RV Water Pump
12V
8.00A
96W
20
3
Stove Vent Fan
12V
2.00A
24W
60
2
LED bulbs (x30)
12V
0.21A
3W
240
1
We are rather tech-heavy in our requirements, and we like to use the pressure cooker and blender for meals.
Here are the other options I've been researching, hopefully the tables transfer to this forum:
Solar Panel Options
Panel Name/Link
Output
Vmp
Imp
Weight
Dimensions
Price
Total Cost
Suntech STP280-24Vdc pickup
280W
35.2V
7.95A
59.52lb
77h 39.1w 50mm
$215.00
$1350.00
ReneSola JC260M-24/BB
260W
37.6V
8.53A
40.78lb
64.5h 38w 40mm
$196.86
$1450.17
Amerisolar AS-6P30-250
250W
37.2V
8.74A
48.4lb
65h 39.4w 40mm
$170.00
$1647.19
Charge Controller Options
Controller Name/Link
Type
Input
PV Max
Output Volt
Output Current
Price
Outback FLEXmax60
MPPT
60A
125 Vdc
12/24/48VDC
60A@12/24/48V
$470.00
Xantrex XW 60-150
Schneider Conext XW 60-150
MPPT
60A
140 Vdc
12/24/48VDC
60A@12/24/48V
$542.52
$515.00
Midnight Solar Classic 150
MPPT
96A
204Vdc
12/24/48VDC
96A@12V 94A@24V 86A@48V
$540.00
Midnite Solar Classic 200
MPPT
79A
200 Vdc
12/24/48VDC
79A@12V 78A@24V&48V 67A@72V
$607.00
Battery Options
Battery Name/Link
Type
Volts
Ah
Weight
Dimensions
Price
Qty
Cost
Alpha 195GXL pickup
GEL
12V
100Ah
67lbs
12.5w 6.83d 8.5h
$100.00
6
$720.00
Apex APX12-200
SLA
12V
200Ah
117lbs
20.75w 8.25d 9.4h
$249.99
3
$986.64
[h=1]Deka 8GC220[/h]
AGM
6V
205Ah
64lbs
10.25w 7.1d 10.4h
$260.77
6
$1798.56
Inverter Options
Inverter Name/Link
Type
Volts
Watts
Weight
Price
Outback FX2012ET
Invrt / Chrg
12Vdc/120Vac
2000W
$1362.72
Xantrex PROsine 2.0
Invrt / Chrg
12Vdc/120Vac
2000W
$1465.99
Magnum Energy MS Series
Invrt / Chrg
12Vdc/120Vac
2000W
$1385.34
I have room to fit 6 of those solar panels on my roof, for a total of about 1500W and approx. 50A at peak power generation. I ‘think’ either of those Charge Controllers will work, am I correct?
The Inverters listed are all 2000W, and will automatically switch between shore power and solar power charging if shore is available. I am fairly certain I need a pure sine-wave inverter, so I did not look at modified versions. Is there anything else I need to be wary/informed about before making a decision on the inverter? Are those more expensive than I need?
I think that the battery bank might be where I am least informed. I was under the impression that when using 6V batteries, I would have to tie two of them together in series to make a 12V ‘battery’, effectively halving the total Ah of storage for the bank, then put 3 of those pairs in parallel to flesh out the bank. Is this not the case? Can I use six 6V batteries in parallel/series and still have effectively the same amount of storage as if I was running a 6V bank? That doesn’t seem quite right to me…
I know this post was enormous… thank you if you made it this far!
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Propane is for heating, not electricity. Unless you have a very large PV Array (it will be too large to hoist onto an RV)
Batteries - suggest STRONGLY to use Flooded lead acid. GEL is verboten. AGM is 2x the cost and 1/2 the life of FLA.
Your loads are un-sustainable with a 12V system. After each 1Kw of simultaneous load, you move to the next stage of battery voltage, 12, 24, 48V
I don't even have 30 light fixtures in my house, what size of RV is this ??
Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A
solar: http://tinyurl.com/LMR-Solar
gen: http://tinyurl.com/LMR-Lister , -
Sorry if this might have been covered earlier in the thread.....
Appliance
volts (V)
amps (A)
watts (W)
daily use (min.)
Amp Hour (A·h)
Refridgerator
120V
6.25A
750W
1440
1500
OK. This is in an RV. Does that mean you have a typical RV refrigerator (Norcold / Dometic.... ) that is known as a 2 way or a 3 way, where the options are propane or electric? And the electric may be 12 VDC or 120 VAC or both? If you have the typical RV refrigerator that has the propane option then use the propane unless you can plug into campground / shore power. That type of refrigerator uses a resistance heating element for it's electrical option. Bad idea unless plugged into the power grid.Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M -
You have enough big wattage items listed you would be better off with a 24 VDC battery and inverter. I know the issue is that you also have many items built into the RV that operate on 12 VDC. A 24 to 12 VDC converter is one way to cover that. The small DC loads (water pump, lights....) are easily covered with a 24 to 12 converter. However the 12 VDC water heater use has to go to make a more viable system. Again, most RV's use propane water heaters. Some have an electric option but that is relly meant for use when plugged into shore power.
Yes you can series connect two 6 volt batteries to produce 12 volts. You can connect those series in parallel, if needed. However, you are best off if you can minimize the number of parallel battery connections. Solve that by using larger batteries, one with more AH per battery. Or reduce the electrical power use.
In series the volts add up and the AH stay the same.
In parallel the volts stay the same and the AH from each eries string adds.Northern NM, 624 watts PV, The Kid CC, GC-2 batteries @ 24 VDC, Outback VFX3524M -
Draku,
The help we RVers get from these guys is beyond amazing; but on occasion they don't speak from an RV perspective. Foe example, your post generally asks them to size your bank and inverter for you. That's not fair. Their banks mever go down the road. You need ed to stay in RV solar internet sites for those questions. Once you get your sizing determined, these folks are geniuses on how to hook it up the most efficiently and safely.
Now, IMO owning a 38' Class A with solar and a large sustem, Your chart (aka energy survey) is great; but the numbers are too high. Your post assumes you will be boondocking with this systwm. If you are hooked up all the time, the equipment is unnecessary. So, here's where I recommend you start. You are off the grid with mo way to re-excite the electrons in your batteries but by driving a LONG ways or using your generator. The gerator for a couple of hours after everyone witjin hearshot are up is okay. Many boondockers do that to top their bamks off from the night's drain and to operate 120VAC coffee maker, hair dryer, microwave, griller, etc.
But your goal from the post is to replinish the batteries from the sun. Hers's where you start (this os ALWAYS true with solar and RVs): an energy audit. You've started correctly. Yea. What you missed is the bank can't do what your current numbers ask of it. Go back and re-figure your minutes used per day. Based on my and articles I've seen, you may find you are 3x high. Here are just a couple of examples.
Your listing 30 LED lights may actually be a little low if uou look underneath; but there's no way you are going to be using them 240m/da. Mamy boondockers will kill all lights after sumdown. With LED, I think that is overdoing it. Still, every light draws something. Cut off the minutes and the Ah will follow. You can't afford a vent fan boondocking except for the occassional aw-phooey with the bacon. Cook smelly meat oudoors. Failing that due to weather, cook something else inside. Your vent fans are too many minutes for their medium-efficient watt usage. You can run one a few hours; but more than that use lower watt small fans. Like stated above, you cannot at all afford electric heating while boondocking. Having said that, a 12V bed warmer or 12V blanket can be done but only with timers that cut them off when you are asleep.
In short, you don't have to starve yourself of Amps out in the wild; but you do have to be much more conservative than so far.
A panel array on an RV is usually huge at 1,250W. If you can fit the 1,500W, go ahead on. However, if your bank will be fully re-charged by 10:30 before the sun even jits noon, you have wasted momey in panels. Like said above, the key is how many Ah can you get aboard in batteries. BTW, i've not read or heard of any RVers putting in flooded cells, anymore. They just don"t play nice with where we drive our coaches off pavement. The exception is using Lithium Iron Phosphate (LIFo). They are they best things to use in a modern Class A battery bank (smaller, lighter, 80% discharge okay). But still too expensive if saving money is a goal. Unlless LIFo is in uour reach, AGM is probably in your future (Lifeline?). For example, because of their thicker plates and better efficiency inside, you can get 2-6CT's from Lifeline, hook the pair in series to get 12V, and you have 300Ah rated storage. Plus, 2 of these particilar batteries fit in the footprint of a commonly used 12V RV battery. To get the 300Ah they are 2" taller and weigh 186 lbs/pair. If uou need this much power stored in hour bank, which i doubt, you could put 4 pair in (series) and connect them in parallel to accomplish 1,200Ah rated. Since, you don't want to discharge AGMs below 50%, normally, that' still a net of 600Ah at 100%. In designing a solar RV system, you want to assume sunless days. How many is up to you. Let's say you want a bank that can care for you if it is cloudy and the road is too muddy to drive back to pavement requiring you to stay in the overcast for 3 days. That means a 600Ah bank at 50% DOD will let you use 200Ah/day in those circumstances. Most people don't have the space for that large a bamk; so, they just plan for 2 days. You can also rum your genset for a limited time if hour bamk is too low.
200, or even 300Ah/da is an extraordinarily nigh number for 90% of boondockers. See if you can redo your chart and get it down to at least 300Ah/da at 12VDC. Once you've faced,reality about what an RV bank boomdocking can do and cannot do using your emergy audit, THEN you cam size your array and batteries.
Jerry -
AGM is 2x the cost and 1/2 the life of FLA.Propane is for heating, not electricity.After each 1Kw of simultaneous load, you move to the next stage of battery voltage, 12, 24, 48VMountain Don wrote: »You have enough big wattage items listed you would be better off with a 24 VDC battery and inverter.Mountain Don wrote: »Does that mean you have a typical RV refrigeratorpebbledropper wrote: »Once you've faced,reality about what an RV bank boomdocking can do and cannot do using your emergy audit, THEN you cam size your array and batteries.Thus for RVs, one approach is to max out the roof space, and work backwards to what that will power.
Overall, I will be getting 6 large 24V panels each of around 250W. The cost/watt is much better at that price-point and I would honestly be spending less for those 6 panels than for an 800W set of 12V RV (smaller) panels.
I will probably be buying the Outback items listed above (or the Midnight/Magnum setup, it looks like either would work). Unless a 2000W inverter/charger too much inverter for an RV? Would it not work if I decide to go with a 24V battery bank over a 12V?
As far as batteries... I am really unsure as to which I will get. This seems to be the most controversial subject. I wish I could afford Lithium, I think AGM is probably better than SLA for an RV environment, and will probably just end up getting as big a bank as I can fit in my battery compartment. I realise I will have to cut down on a lot of power usage while boondocking... the list above was what we use while on shore power... it will probably be a wake up call when I only have the batteries to work on, but hey... that's part of the adventure! -
Here is my modified power usage chart. Hopefully this is a better and more realistic representation of what I can do in an RV.
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120Vac Daily Use Appliance
volts (V)
amps (A)
watts (W)
daily use (min.)
Amp Hour (A·h)
Laptops (x4) (charge)
120V
6.00A
720W
120
120
Modem LTE
120V
0.80A
96W
600
80
Microwave
120V
12.50A
1500W
15
31
Stereo / Surround
120V
0.50A
60W
240
20
Tablets (Sony x2) (charge)
120V
1.00A
120W
120
20
Phones (x2) (charge)
120V
1.00A
120W
120
20
Tablets (Xoom x2) (charge)
120V
0.60A
72W
120
12
Dyson Vacuum (charge)
120V
0.30A
36W
60
3
TOTAL A·h
306
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12Vdc Daily Use Appliance
volts (V)
amps (A)
watts (W)
daily use (min.)
Amp Hour (A·h)
Hot water heater
12V
41.67A
500W
120
83
Vent Fans (x2)
12V
2.00A
24W
480
16
RV Water Pump
12V
8.00A
96W
20
3
Stove Vent Fan
12V
2.00A
24W
60
2
LED bulbs (x30)
12V
0.21A
3W
240
1
TOTAL A·h
105
Total possible daily usage:
411 A·h
-
Occasional Use Appliance
volts (V)
amps (A)
watts (W)
duration (min.)
Amp Hour (A·h)
Breadmaker (3.5hr per loaf)
120V
5.00A
600W
210
175
Router E3000
120V
0.80A
96W
600
80
Pressure Cooker (30min per meal)
120V
8.33A
1000W
30
42
Grill Electric (30min per meal)
120V
5.00A
600W
30
25
Fans (x2)
120V
0.83A
100W
0
0
Popcorn Popper
120V
12.00A
1440W
10
20
Waffle Maker (30min per meal)
120V
1.83A
220W
30
9
Blender (5-10min per smoothie)
120V
11.50A
1380W
10
19
Toaster (3-4min per 2 slices)
120V
6.25A
750W
5
5
TOTAL POSSIBLE
375
-
Propane/Electric Appliance
volts (V)
amps (A)
watts (W)
daily use (min.)
Amp Hour (A·h)
Refridgerator
120V
6.25A
750W
0
0
Heater
120V
10.00A
1200W
0
0
A/C
120V
9.17A
1100W
0
0
TOTAL POSSIBLE
0
-
Hi Drauku,
Just quickly, you are trying to be very complete with your list of possible loads on the inverter, and this is a very good place to start.
BUT, those loads are so HUGE for almost any (essentially) off-grid system, that it just seems to YELL that many of these loads should not be on the list at all. AND, it also implies that perhaps a 48 V system would be best, which may be difficult in many RV applications, due to possible space limitations.
Many 250 W PVs are NOT real 24 V modules, as they most often have Vmps in the 29.5 - 30.5 range. This means that they will generally not be able to fully charge a 24 V battery bank using only parallel strings (often desirable in RV apps, due to shading issues).
One last thing, AGMs can be good in RVs for several reasons. But AGMs generally have about half the life of Flooded batteries, if for no other reason than the fact that they use a chemical Catalyst to recombine Hydrogen and Oxygen back into water. These gasses are liberated in the Absorption stage of charge. This catalyst is consumed over a period of time, and when it stops working, the recombination fades, and the battery croaks.
Also with AGMs, the inability to actually measure the State Of Charge (SOC) means that these batteries can easily be under/over charged, which in not good for any battery -- there is really no free lunch. Maintenance-free batteries still need quite a bit of twiddling, that twiddling is just in a different form than measuring SGs and adding water, etc.
All just my opinions. Keep at it. Defining loads, and CONSERVATION are the very best places to start, and you are doing that. Have Fun, VicOff Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes. 25 KVA Polyphase Kubota diesel, Honda Eu6500isa, Eu3000is-es, Eu2000, Eu1000 gensets. Thanks Wind-Sun for this great Forum. -
OK... We at least have a starting number 6x 250 Watt solar panels--What would a rule of thumbs system look like. These will be "conservative numbers"--If you pick AGM or LiFePO4 batteries, do more DC than AC power (inverter averages around 85% efficiency), etc.. You can do a bit better (maybe 10-20% more solar power available)...
First, what size of battery bank. Nominally, we recommend 5% to 13% rate of charge from solar. Weekend use, 5% can work. Full time off grid (avoiding generator use), I would suggest 10% or more rate of charge (i.e., smaller AH battery bank). I will use a 12 volt battery bank--But suggest that for battery banks >~800 AH, that you jump up to the next voltage (24 or 48 volts). But for the sake of math, it really does not matter (200 AH @ 12 volts is the same stored energy and physical size battery bank as 100 AH @ 24 volts).- 6x 250 Watt array * 1/14.5 volts charging * 0.77 panel+controller deratings * 1/0.05 rate of charge = 1,593 AH @ 12 volt (or 797 AH @ 24 volt) largest suggested bank
- 6x 250 Watt array * 1/14.5 volts charging * 0.77 panel+controller deratings * 1/0.10 rate of charge = 795 AH @ 12 volt battery bank nominal
- 6x 250 Watt array * 1/14.5 volts charging * 0.77 panel+controller deratings * 1/0.13 rate of charge = 613 AH @ 12 volt minimum battery bank
- 795 AH * 12 volt battery bank * 1/2 day storage * 0.50 max discharge * 0.85 AC inverter eff = 2,027 Watt*Hours per day of storage (bad weather, over night, etc.)
- 795 AH * 1/2 day storage * 0.50 max discharge = 199 AH per day (over night, bad weather day) for 2 days of storage
- 795 AH * 12 volt battery bank * 1/1 day storage * 0.50 max discharge * 0.85 AC inverter eff = 4,055 W Watt*Hours per day (1 day of storage)
- 795 AH * 1/1 day storage * 0.50 max discharge = 398 AH per day (over night, bad weather day) for 1 day of storage
http://solarelectricityhandbook.com/...rradiance.html
Oklahoma City
Average Solar Insolation figures
Measured in kWh/m2/day onto a horizontal surface:
Jan
Feb
Mar
Apr
May
Jun
2.59
3.20
4.29
5.40
5.84
6.32
Jul
Aug
Sep
Oct
Nov
Dec
6.73
5.86
4.81
3.72
2.75
2.33
Toss out the bottom three months (assume generator/utility power to make up power needs for low sun):Efficiency:- 0.77 panel+charge controller eff * 0.85 AC inverter efficiency * 0.80 flooded cell Lead Acid Battery efficiency = 0.52 end to end efficiency with AC inverter
- 0.77 panel+charge controller eff * 0.9 AGM battery eff = 0.69 end to end DC efficiency with AGM
- 6 * 250 Watt array * 0.52 system eff (lead acid, AC inverter) * 3.2 hours of sun (February) = 2,496 Watt*Hours per day (long term average) from solar for 120VAC power
- 6 * 250 Watt array * 0.69 system eff (AGM, no inverter) * 3.2 hours of sun (February) = 3,312 WH per day (DC energy with AGM bank).
- 6 * 250 Watt array * 0.69 system eff (AGM, no inverter) * 3.2 hours of sun (February) * 1/12 volt battery bank = 276 AH @ 12 volts (very roughly)
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Ok. Bills given you a great math model, it will serve you well. Reread it till it makes sense. Other things:
Its always cheaper to use energy more efficiently than to produce it. Thus your load budget needs more work. Some tips;
- tally in Wh/d, not amp hours
- dont rely on nameplate specs, most of your numbers are too high. devices cycle or otherwise dont always run ar full spec. get a kilawatt and measure them. Failing that estimate based on actual run time (eg fridge 75W compressor 24 hours 50% duty cycle). (eg 40W laptop adapter: 10W during charge only, 20W charge plus light usage).
- one doesnt use all of everthing one has every day, try to find an average day scenario.
- but remember that in general there will be one or two key loads, and everything else is small change. (A blender might draw some amps but its for such short periods, the effective Wh is tiny. )
- fridge, im the other way, who wants to be refilling propane every couple weeks. find the most efficint dc fridge you can, regardless of price. expect to pay 1K+ for something under that runs under 600Wh/d. Something with a danfoss compressor.
For 1500w solar please just forget 12V. Youll understand in time.(like after youve had to buy two charge controllers instead of one etc).
Agms are actually a good and typical solution for RVs. Yes they have disadvantages that land lubbers are better off without, but RV and marine make a good use case for AGM, and increasingly LiFePO4. But forget the lithiums until your second bank, by then youll be battery safe, and the tech will be cheaper as well. I hear RV folk rave about fullriver as a brand, other good brands are lifeline / odysey.1.8kWp CSUN, 10kWh AGM, Midnite Classic 150, Outback VFX3024E,
http://zoneblue.org/cms/page.php?view=off-grid-solar -
For RVs, their owner's manual usually lists what the maximum electrical consumption is, when everything is turned on. Look for that number, because it may not be same as the type of electrical plug your RV is supplied with. For example, your 32 ft 5th wheel could have a 30A or 50A plug. I have an older 31 ft 5th wheel, and it has the 30A RV plug. With everything turned on my RV draws 55 Amps. Instead of slowly burning up my 30 A connector, I supplied a 2nd 20 amp circuit from shore power. Without it, my refrigerator/freezer was slowly losing temperature whenever I had to run the Air Conditioner.
It is so important that you consult your owner's manual for the maximum power draw.
How many of your appliances can switch between electrical or propane? Items such as the lighting and water pumps, might just use DC from a power converter. Also, if your 5th wheel has built-in heating, that probably runs off of propane only (spark is electric, heating is gas). You also have parasitic loads such as the LPGas detector, which federal law mandates must be on all the time. For this reason you House battery must also be properly charged. -
get a kilawatt and measure them
All this advice has been awesome! I think I've grounded my expectations and I’ve done a good bit of alteration with the setup I had, so here’s the current parts-list.
Solar Panel Name/Link
Output
Vmp
Imp
Weight
Dimensions
Qty
Price
Amerisolar AS-6P30-250
250W
37.2V
8.74A
48.4lb
65h 39.4w 40mm
1
$170.00
Stats for 6 panels
1500W
112V
52.44A
290.4lbs
6
$1270.00
Panels will be wired in three sets of two panels, pos to neg on the panels, then the pos/neg leads into the combiner box.
Charge Controller Name/Link
Type
Volts
PV Max
Battery Volt
Output Current
Cost
Midnight Solar Classic 150
MPPT
150Vdc
204Vdc
12/24/48Vdc
94A@24V
$607.00
Inverter Name/Link
Type
Weight
Watts
Volts
Cost
Schneider Electric SW2524
Invrt / Chrg
2000W
24Vdc/120Vac
$1170.00
Battery Name/Link
Type
Volts
A·h
W·h
Weight
Dimensions
Qty
Price
Apex APX12-200
AGM
12V
200Ah
2400Wh
117lbs
20.75w 8.25d 9.4h
4
$249.99
24V
400Ah
2400Wh
468lbs
½” clearance min
$1252.11
Batteries will be set up in a 24V bank, two batteries in series, two parallel sets connected to the inverter.
I will be buying MC4 cables from Amazon (best price I’ve found, http://amzn.com/B00KFL0GIA).
The longest cable run from a panel to the combiner box/charge controller should be no more than 50ft (one set of 2 panels). The other 2 sets will each be 25ft runs. Between the charge controller and the batteries will be only a couple feet of cable. Battery cables I’ll buy from a local store as I’m not sure exactly what lengths I’ll need yet. From the Battery to the Inverter will be about 6-7ft.How many of your appliances can switch between electrical or propane?Ok. Bills given you a great math model, it will serve you well. Reread it till it makes sense. Other things:I will stop here--There are a lot of variables here, and I have given you the basic math--You can play with the numbers/assumptions and see what works best for you.
-
As someone who boondocks 90% of the time besides what has already been mentioned you need to conserve, use LED lights, conserve, use less heat; extra clothing or blankets/sleeping bags. Use propane as much as us can. Take a look at the 20 Golden Rules of Solar, jackdanmayer.com He will tell you the same thing as HandyBob without the rant. They are both good resources. And again conserve.
-
Wow, the forum format really changed and messed up the tables I had posted.
I have my panels, batteries, charge controller and inverter installed. The inverter arrived DOA, so it is at the factory being repaired or replaced. I'm able to charge the batteries and hooked them up to the 12V system in the RV (after re wiring them to 12V of course) but that only runs lights for now.
Thanks scrubjaysnest, I'll check out the website you recommended.
On an aside... industrial 3M tape only secured 5 of my six panels while driving on the highway at 65mph. I lost a panel on this last trip -
I got the inverter back from the factory, and everything is installed and working well.
We are currently parked in the St Louis area, and it got down to 22F the other night. We were able to run our space heater all night long without discharging the batteries below 50%. Even with 4 out of 6 panels I was able to fully recharge the batteries by mid-afternoon. I think I might have more panels than my batteries can handle! I only wish I had more space to put in more batteries... there just isn't room.
The company I purchased my inverter from refused to pay for return shipping even though the inverter was DOA. Perhaps that is a standard in the industry, but I feel it is a very bad customer service practice. The inverter was either repaired or replaced, but I'm still out an additional $100 in shipping costs. Don't buy from AIMS Power, they don't stand behind their product.
-
Your not out of luck as if you paid for by credit card you can dispute this charge regardless of what Aims terms are. This is common these days as ask anyone who has had a merchant account or have sold with paypal etc. The stores terms are useless as the credit card processor is the boss and makes the rules as it goes. Trust me as I have been burned many times by customers making false claims but on the other end of the coin I have been refunded by dishonest sellers. So I think you should call your card company and see what they can do. Hope this helps.
By the way Aims inverters look good on the spec sheet but you are getting the lowest quality product at a mid price level. So your paying too much. Better off with a Samlex or Cotek or even a Kisae Inverter. I have a Cotek SB2000 Inverter Charger that is as complicated as it gets to install due to its features and I am still learning on how to use it. Next time I will go simpler.
Magnum is supposed to be the best by some people and I suggest as the only inverter to buy for fulltime living or for hard core boondockers and or rich people as it is pricey.
I am in the repair service business and In my tool box I have Taiwan cheap tools that at one time a Joke to have as they were garbage but I was young after tech school so I could afford until I upgrade. But I always used a Fluke Meter as some things you cant get by cheap. Now Taiwan stuff is considered good and the Chinese stuff is garbage. But Chinese stuff is cheap and getting better quality. But when out on the road only Snap-On will be with me. Not a product snob as I own the best when I can afford and get by with cheaper stuff so I can buy the best most important stuff.
2008 Class C Four Winds Chateau Sport 28A
-
Excellent suggestion, thank you marxman! I'll give my credit card company a call and see what they can do.
Thanks for the suggestions on inverter brand names. I was looking at those as well, but the Solar shop I ended up getting a lot of my items from recommended AIMS and it's rather unfortunate that they did. Not a deal breaker though, as the inverter is working well for my purposes in the RV. -
Drauku said:Hello all! Thanks in advance for any suggestions you might have regarding this project. I'm living full-time in a 32' 5th wheel with my wife and two daughters and a cat. We want to convert our coach to allow for 100% off-grid use, and here's my beginners attempt at a setup that will 'start' to satisfy that goal.
250 W Watt Poly Panel 24V (solartec)
6
Solar Odyssey 2000W/24V Pure sine wave Inverter/Charger
1
Solar Odyssey 50A MPPT Controller
1
PV Wire 10 AWG 600V UL Class [100 feet ]
100
Z Brackets Mounting System
6
12V AGM Batteries @100AH X 6
6
Y Branch Connectors
2
15 A Fuses With Holder
6
10 Pair MC4 Connecter
1
I will be picking up battery wire from a separate vendor, along with connectors for the battery terminals.
My plan is to wire the 6 panels in parallel with a 15A fuse per panel into the charge controller, then to the batteries in parallel (wired per suggestions at http://www.smartgauge.co.uk/batt_con.html thanks to Apples on this forum). The batteries are then wired with a ??A fuse (not sure how to determine the Amps needed for this fuse) to the Inverter input, and the Inverter output goes to my RV converter/main RV power. Additionally, this Inverter can also act as a generator/shore power charger for the battery bank, so I will wire the shore power into the charger-in on the Inverter.
As an aside, is there a way to get my Air Conditioner to run on the batteries? I know it will use up a lot of my power, but sometimes I will need to let it run to keep the cat temperate while we are away for short trips.
Any suggestions would be greatly appreciated. I plan on buying this list in the next couple days unless there are some huge change suggestions. Thanks in advance! -
RussOnTheRoad said:I don't know enough to comment on your proposed plans. My thoughts here are running in a different direction which is that of wieght limitations. I was looking at the weights of 12 volt panels and batteries for my own situation and the 150 watt panels weighed something like 27# without mounting hardware. Batteries can easily be 90# each. A four battery, 4 panel system could easily weigh 500#. When it comes to towing a 5th wheel with a family of four and all their stuff, are you certain you'll be within the various weight limits of your RV and your truck?
MidNite Solar MPPT charge controller: 13 lbs
Amerisolar AS-6P30-250 panels: 6 @ 18.5kg = 245lbs
Deka APX12-200 AGM batteries: 4 @ 114lb = 456lbs
AIMS Power Inverter/Charger: 64lbs
Misc wires and install kit: 20lbs
Total Installation Weight: 798 lbs
-
marxman said:
Your not out of luck as if you paid for by credit card you can dispute this charge regardless of what Aims terms are. This is common these days as ask anyone who has had a merchant account or have sold with paypal etc. The stores terms are useless as the credit card processor is the boss and makes the rules as it goes. Trust me as I have been burned many times by customers making false claims but on the other end of the coin I have been refunded by dishonest sellers. So I think you should call your card company and see what they can do. Hope this helps.
By the way Aims inverters look good on the spec sheet but you are getting the lowest quality product at a mid price level. So your paying too much. Better off with a Samlex or Cotek or even a Kisae Inverter. I have a Cotek SB2000 Inverter Charger that is as complicated as it gets to install due to its features and I am still learning on how to use it. Next time I will go simpler.
Magnum is supposed to be the best by some people and I suggest as the only inverter to buy for fulltime living or for hard core boondockers and or rich people as it is pricey.
The AIMS inverter burned out a couple days ago, leaving us high-and-dry without any form of power, since of course we can't even access our solar array without the inverter installed. The company has said they will honor the warranty still, but will not reimburse for shipping... apparently this is standard across the industry? I've never heard of that, but then again I haven't bought these before.
I wish I had realized how much of a pain buying an AIMS inverter would be... I'll be upgrading to a Magnum inverter as soon as we are stationary again, and can schedule shipping.
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