Best system

The battery bank voltage does not really affect "efficiency" that much... It is much more based on your peak wattage (loads), Watt*Hours (or Amp*Hours at what voltage), battery bank AH capacity (at what voltage), etc.

Roughly, if your AC (or DC) loads are over ~1,200 to 1,800 Watts continuous, or your battery bank is >~800 AH, you might think about going to 24 volts.

If your AC loads are small--I.e., around 300 Watts max continuous, a 12 volt MorningStar TSW AC inverter is hard to beat. Reliable, and has remote on/off + low power "search mode".

And you need to look at your solar array size too... 5x 335 Watt panels:

• 5 * 335 Watt panels * 0.77 panel+controller derating * 1/14.5 volts charging = 89 Amps solar charging current

That is pretty much right on the ragged edge of the highest amp output solar charge controller (around 80-90 amps for several brands). Or you would need to get 2x 60 amp controllers (for example).

You also need to look at the Vmp of the solar panel... Yours appear to be Vmp~37.7 volts. That would work well with a 12 volt battery bank and an MPPT charge controller (down converts from 37 volts to ~14.x volts for efficient energy conversion). Running a 24 volt battery bank, 37.7 volts Vmp would be fine with PWM type charge controllers (get two x 60 Amp). Optimally, you would would be looking at Vmp array with 2 panels in series (Vmp~74 volts), however, you have room for 5 panels. This means that you either need 6 or 4 panel array (if you use MPPT controller and 24 volt battery bank).

You can get away (possibly) with 5 of those panels in parallel for 24 volt VDC and MPPT controller--It is just less than ideal (i.e., if you are camping in the desert, Vmp-hot can be down near 0.80*37.7volts=30.2 volts--Very near the battery charging voltage of ~29.x volts--Not accounting for MPPT controller and wiring voltage drop).

You have to verify the Vmp of your panels... The same vendor makes very similar panels with Vmp~30 volts--Those panels are not good for charging a 24 volt battery bank with one panel in series strings (too low of charging voltage for 24 volt battery bank when panels are in normal operating conditions--Vmp falls as the panels get hot).

-Bill

The Midnite Classic 150 is a very popular and versitile charge controller. Just make sure you install it (and any charge controller) in a space with good air circulation (5%*1,500 watts = 75 Watts of heat). Also, Midnite Classics (and many other brands/models) have fairly noisy fans in them--Do not install them in a room, space, or office that is occupied during the day.

You might also take a look at our host's website (forum is open to all--I do not work for NAWS, just a volunteer here):

http://solar-electric.com/

Location matters--As what season(s) you will be using the RV. For example if you mount the array at a ~40 degree angel (from horizontal):
http://www.solarelectricityhandbook.com/solar-irradiance.html

Toms River
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 50° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
3.16	3.83	4.40	4.65	4.81	4.96
Jul	Aug	Sep	Oct	Nov	Dec
4.96	4.84	4.69	4.25	3.23	2.87

If you mount flat to roof (typical RV mounting):

Toms River
Average Solar Insolation figures

Measured in kWh/m2/day onto a horizontal surface:

Jan	Feb	Mar	Apr	May	Jun
1.92	2.71	3.69	4.57	5.22	5.61
Jul	Aug	Sep	Oct	Nov	Dec
5.51	4.97	4.15	3.13	2.07	1.66

If you do winter camping, flat mounts in the "closer to pole" regions, will cost you a lot of solar energy.

In general, I really like using a 120 VAC inverter (right tools for the right jobs). Understand that a 12 volt battery bank can run from ~10.5 volts (discharged battery under heavy load+voltage drops) to >15.0 volts.... Many "12 volt" appliances and adapters do not like that wide of voltage range (the MorningStar only works to ~15.0 volts--Would have been better if >16.0 volts when equalizing your battery bank).

Keeping your loads "small and efficient" will really help extend your solar power without spending a bunch of money. 300 Watts will run a bunch of small/efficient AC loads (LED lighting, cell phone chargers, laptop computers, etc.). And leave the 12 VDC for the RV Water Pump, 12 VDC LED lighting, and other small DC loads that are not worth converting to AC.

Just to give you an idea of how much energy a properly designed system can output (long term average--Day to day weather will vary).

• 5 * 335 Watt panels * 0.52 off grid AC system eff * 4.0 hours of sun per day = 3,484 Watt*Hours per day

That is enough energy to run a very energy efficient off grid home (refrigerator+washing machine). ~3.3 kWH per day or ~100 kWH per month.

There are a lot of "gotcha points" when designing your off grid power system. I really like to design a "balanced" systems... Basically, design the battery bank to support your power needs, then the solar array (and backup genset, if needed), to keep the battery bank happy.

In general, do not do things that push the limits. Yes, you can buy a 4kW 12 Volt AC inverter and connect it to 4x 6 volt @ 200 AH batteries, and 400 Watts of solar panels--But for the long term, it is not a very capable system (4x golf cart batteries would, reliably, support around a 1,000 Watt maximum AC inverter. A 4,000 Watt inverter may take 20-40 Watts just to "turn on"--More wasted power).

-Bill

What is your battery bank? For a 12 volt battery bank, I would suggest the minimum size to support a 1,500 Watt AC inverter would be around ~600 AH @ 12 volts minimum (for example 2x series * 6 volt @ 200 AH flooded cell golf cart batteries by 3x parallel strings).

That should be a good AC inverter (Cotek seems to be a good middle of the road AC inverter--I am not in the solar business, others here can speak to their experiences). I like that it works to ~16.5 VDC on the input.

Do you need 1,500 Watts? It takes 1.8 amps * 12 volts (~22 Watts) just to turn on. The MorningStar takes ~6 watts.

Some folks have two inverters, one large one for daytime loads, and a second small one for smaller night time/off peak loads.

The wiring for a 1,500 Watt inverter:

• 1,500 Watt * 1/0.85 inverter eff * 1.25 NEC wiring+breaker derating * 1/10.5 volts minimum = 210 Amp minimum rated branch wiring and breaker... Doable--Just need heavy wiring+breaker to keep voltage drops down.
  

-Bill

The vendor says they are for starting batteries--Does not say anything about deep cycle applications.

For various reasons, I really do not like paralleling 12 volt batteries into 12 volt banks--2x 6 volt batteries makes it easier to do a quick check on the health of the batteries (i.e., you can measure 6 volts across each battery and see if they are high/low during charging and discharging. Measuring across 12 volt batteries in parallel just gives you the "bank voltage", not the individual battery voltage). A DC Current Clamp meter does make things easier--You can verify that each battery (or string of batteries) is properly supplying current and taking charging current (open/shorted cell detection, bad wiring, etc.).

AGM Batteries are nice Lead Acid batteries (cleaner, higher surge current). They tend to be a bit sensitive to over voltage during charging. Also, they tend to have a bit shorter life than equal cost flooded cell batteries. And AGM usually cost more.

If this is your first bank--Flooded Cell batteries are nice because you can use a hydrometer to check state of charge/overall health of the battery bank. AGMs are sealed batteries and a bit harder to estimate capacity/state of charge.

Many people "murder" their first battery bank or two--Using cheaper batteries can be a better solution.

For example, here is a 6 volt @ 250 AH AGM deep cycle battery (a couple people here have said Fullriver seems to work well for them):

https://www.solar-electric.com/fullriver-dc250-6-agm-sealed-battery-6v-250ah.html

It is much more expensive than the battery you linked too--May be too pricey for your needs. Talk with your battery vendor(s) about their batteries and see if they warranty them for Deep Cycle / Off Grid solar use (many good quality AGM batteries are for starting/UPS usage--Not deep cycling).

-Bill

And some end of life/failure modes for AGM (and other Lead Acid Sealed Batteries)--They will vent hydrogen+oxygen gasses and electrolyte (there is a catalyst in many sealed batteries to recombine hydrogen+oxygen--But the catalyst does have a limited life and will eventually wear out. And over voltage/charging will generate a lot of gasses, and can overheat the catalyst to failure--And venting).

-Bill

Those numbers do not make a lot of sense... More likely:

Air conditioner    1,000 Watts > 1,000w * 0.5 duty cycle * 8 hours per day = 4,000 WH per day
Dish Washer    435 Watts (maybe 1,500 Watts peak) >  435w * 1.5 hours run time = 653 WH
X-Box    195 Watts > 195w * 5 hours playing = 975 WH
Box Fan    175 Watts > 175w * 8 hours = 875 WH
Coffee Maker    900 Watts > 900w * 1/6 hour = 150 WH
Led Light Strip   10 Watts > 10 Watts * 4 hours = 40 WH
Microwave    900 Watts > 900 Watts * 1/15 hour = 60 WH
TV    55 Watts > 55w * (5 hours + 5 hours Dish) = 550 WH
Toaster    900 Watts > 900 Watts * 1/20 hour = 45 WH
Refrigerator   120 Watts (600+ VA starting, defrosting) > 120 Watts * 0.5 duty cycle * 24 hours per day = 1,440 WH
Water Pump    300 Watts > 300 Watts * 1/4 hour per day = 75 WH
Dish Network    30 Watts > 30 Watts * 5 hours per day = 150 WH
Blender    800 Watts > 800 Watts * 1/30 hour per day = 37 WH

This would probably be a way to large of system for off grid use (many $10,000s of dollars worth of hardware).

Just to give you an idea... Guess that your solar power costs you $1 per 1,000 WH. Using the above (guesses), your power per day would be:

A/C $4 per day
Dish Washer $0.65
X-Box $0.98
Box Fan $0.88
Coffee Maker $0.15
LED strip $0.04
Microwave $0.06
TV $0.55
Toaster $0.05
Fridge $1.44
Dish $0.15
Blender $0.04
==================
$8.99 per day or ~$269.70 per month (or as high as $2.000 per 1,000 WH or ~$540 per month--And you have to pay 5-10 years worth of power "up front"--12 months * 7 years * $269.70 per month = $22,654.80 to ~ $45,000 for hardware costs)

The realistic costs of solar power are probably $0.50 to $2.00+ per kWH. If you are really good at getting deals, install it yourself, and use most of the energy generated every day (365 days per year), you may get down to $0.50 per 1,000 WH. If you are there weekends/seasonally, or have large summer loads and light winter loads, you may be $2.00 per 1,000 WH (per 1 kWH).

Also note that heavy loads also mean a large battery bank and AC inverter to run them. To run a microwave may not use much energy (WH) per day, but you still spend money on large inverter + battery bank.

Realistically, you do not have all loads turned on at the same time for a small to medium sized home.

Going off grid solar--You have to have to have a completely different attitude about your energy usage. Your $54 per month utility bill becomes something like $270 to $540 per month bill if you do not cut way back on your power usage (conservation).

The A/C system, Refrigerator, Entertainment, and Box fan would be (my guesses) be your largest energy consumers. And where you should start looking at how much you really need them. And if you really do need 120 Watt * 12 hours per night LED Strip Lighting, then that is like adding a second refrigerator (another $1.44 per day).

And if you really want to run all loads at the same time (A/C, toaster, microwave, fridge, blender, water pump) at the same time--Then you need very large Inverter (4,000 watt or larger) and a 400 AH @ 48 volt battery bank (or larger).

Don't get wrapped up in picking (and buying) solar equipment yet--That is putting the cart before the horse. Get a better understanding of your loads (energy needs) and your budget. Energy usage is a highly personal set of choices. What works for me may not work for you. If you need a large system, and have the available cash to build it--That is fine. We just want you to understand the trade-offs with solar power systems.

Get a Kill-a-Watt meter or similar to measure your AC power loads and see what your proposed devices really draw.

https://www.solar-electric.com/kiacpomome.html

-Bill