Another newbie

System

I am in the process of getting some equipment rounded up for a decent system for my 5th wheel. Here is what I use through out the day.

105 Watts TV 8 hrs a day
28 Watts 2 refrigerators 8 hrs a day
100 Watts Data Storm equipment 8 hrs a day
27 Watts Direct TV box 8 hrs a day
50 Watts reading light 4 hrs a day.
_______
310 watts

I will be dry camping around 3 months out of the year for now.

I am thinking 2 Kyocera KC-130 panels, 4 T105's 6 volt batteries.
I have a Honda Eu2000 generator to help top off the batteries for those cloudy days and run the microwave.
I have already purchased a 25 amp controller with mppt. Any recommendations or suggestion will be appreciated.

System2

Re: Another newbie

oldnewbie wrote:

105 Watts TV 8 hrs a day
28 Watts 2 refrigerators 8 hrs a day
100 Watts Data Storm equipment 8 hrs a day
27 Watts Direct TV box 8 hrs a day
50 Watts reading light 4 hrs a day.
_______
310 watts

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First lets take a look at your power requirements.
105 watt TV for 8 hours - - - - - 8X105= 840 Watt HOURS
2 FRIDGES - - - - - - - - - - - 28 x2x8 = 448 WH
Data Storm System - - - - - - - 100X8=800 WH
TV Box - - - - - - - - - - - - - - - 27X8=216 WH
Light - - - - - - - - - - - - - - - - - 50X4=200WH
TOTAL consumption per day - - - - - 2504 Watt Hours

Sorry man, the two PV's you have been thinking about will probably produce less than half that much on a good day, and far less on a not so good day, and that's not taking into account the inefficiencies that WILL exist in the system.
I would suggest going back and having a look at conserving use. For instance, change that 50 watt reading lamp, to a 10 or 13 watt CF lamp. Same, or more light for less than 1/4 the power used. Look at LCD TV's, usually much lower consumption. Do you need two fridges? It's much cheaper to conserve, than to make electricity. A lot of the newer TV boxes use a lot less than 27 watts too.
Also, are you sure the fridges only use 28 watts?
Keep in touch and let us know how things are going.
All the best and good luck.
Wayne

System2

Re: Another newbie

thanks Wayne

the TV box is less than 3 months old from Direct.
the 2 refrigerators run on propane except the starters, I assume the 28 watts was for that. also 28 watts is for both refrigs. yes the reading light can be cut back.

System2

Re: Another newbie

OK man, thanks for clearing that up. Now we'll sit back and see what some of those with more experience and more on the ball than I, have to say.
Good luck and cheers
Wayne

niel

Re: Another newbie

not going to happen with all those loads listed. 260w of stc rated pvs may give you about a kwh (1000wh) or so on a decent day getting full sun. this means they must be aimed at the sun and not flat on the rv roof with about 5 hours of full sun (1000w/m2^ or more) along with the inefficiencies too. also be carefull as you are charging with a very low charge rate. 7.39a x 2 =  14.78a / 450ah battery capacity = 3.28%. this means let the batteries charge during sunny periods and without any loads at all until the batteries reach a full charge. at that % it will be minimumly 15.25hrs of full sun with the batteries not allowed to exceed 50% depth of discharge (dod). that 50% dod point is about 2700w of battery power so you roughly got this part right. it will take many days at this rate of charge from 2 kc130s to allow the batteries to fully recharge and only then could you use the battery power again. to do otherwise would cause the batteries to sit too long without receiving a full charge and lead to sulphation and premature battery death. now you could argue that the mppt will up the current some and you'd be right, but it's not going to be that much for you to be able to add more loads as it will take longer for the absorb stage to bring the last 20% of charge to the batteries as that's delivered at a lower charge rate. it roughly evens out.
do cut back on the appliances used with such a system for if you can only supply x number of watts of power per day from pvs - the losses and inefficiencies along with your loads then you should not use more than that to keep the system from depleting its power too soon and result in many days for a full recharge. simply put, only consume what you can usably generate. do get the battery temperature sensor if you did not already buy it. i would've recommended more pvs and a larger controller to better charge those batteries and keep up with your loads, but you bought the controller already so not much expansion will take place and certainly no more kc130s can fit onto the controller. the output of 25amps means an input of 20a max so whatever total current you have in pvs x 1.25 should be 25a or less. you could expand a bit over 5amps in pvs so about another 85w of pv could be added bringing the still low % to about 4.4%. we generally recommend at least a 5% charge rate, but it can work if you are careful.

crewzer

Re: Another newbie

Oldnewbie,

As indicated, the projected energy requirement is way beyond what your proposed solar energy system will be able to power. You’re probably going to have to look at both cutting energy needs as well as growing the RE system. This may not be as bad as it sounds, as it's often cheaper to invest in conservation that to buy the additional RE equipment otherwise required.

Two places to cut energy needs are with the TV and the reading light. My 15” LCD TV draws ~22 W on and ~ 1 W when off. See: http://www.wind-sun.com/smf/index.php?topic=1838.msg13182#msg13182 You should look into an LED reading light such as something from here: http://www.superbrightleds.com/MR16_specs.htm

So, substituting some new load values changes your energy requirement as follows:

LCD televison: 22 W x 8 hrs/day = 176 Wh/day
2 refrigerators: 28 W x 8 hrs a day = 224 Wh/day
Data Storm equip: 100 W x 8 hrs a day = 800 Wh/day
Direct TV box: 27 W x 8 hrs a day = 216 Wh/day
LED reading light: 10 W x 4 hrs a day = 40 Wh/day

TOTAL: 1,456 Wh/day.

Assuming the equivalent of ~4.5 hours/average day of “full” Sun and overall system efficiency of ~67%, you’d need a PV array rated at 1,456 Wh/day / (4.5 hrs/day x 67%) = ~483 W (STC). That would something like ~4 of the KC-130 PV modules.

Assuming powering everything from 12 V, 1,456 Wh/day would require a battery bank rated at 1,456 Wh/day / 12 V = 121 Ah/day. Assuming three days of autonomy and limiting battery discharge to 50%, you’ll need a battery bank rated at 121 Ah/day x 3 days / 50% = 726 Ah. That would be something like six of the T-105 batteries wired in series / parallel to make 12 X x ~675 Ah, or, even better, three size 8D AGM batteries wired in parallel to make 12 V x ~750 Ah.

HTH,
Jim / crewzer