Solar Panel Output for RV Trailer

In series you will get 108vdc. Go with parallel, a PV regulator to the batteries, then an inverter for your 120vac supply, switched so you don't have the inverter running when you reconnect to grid power. Make damn sure your panels are mounted to withstand hurricane force winds, and mounting hardware (SS, through bolted to the frames) and caulking,(polysulfide) should be of top quality The amount of power you get depends on panel orientation to the angle of the suns rays. A flat array will give optimum power for about 3 hours, tapering off both sides of high noon.

Thank you. Any input toward battery type, quantity, etc? i.e. automotive batteries??

Deep cycle marine batteries are best. The 'Gel' type are more expensive, hold less wattage, and are not necessary unless you spend a lot of time heeling to leeward. Use a marine isolator switch between your storage and your starting battery.

6 volt L-16 batteries are best. 2 in series. 300+ Ah and 'true' deep cycle. If you set up the system correctly you can have the grid provide for shortcomings in power production when you can grid connect and have the PV's make up the bulk. The 30amp rating is for the inverter... a 3.6kVA inverter will supply the equivalent of your 30 amp grid connection. I doubt you are using 3600 watts/ hour continuously. Purchase something like the 'watts-up' and you can get accurate survey of your power consumption and gauge the amount of PV power you really need. BTW you can run 108 volt panel arrays into a variety of charge controllers which will convert to your battery voltage. Higher volts=smaller wiring and most panels are sold set for series arrays with quick couplings.

Well six 80W panels will give you a maximum of 80x6 = 480W under ideal conditions. Series/parallel connection will depend on the type of inverter you are intending to use, commonly the input voltage for the panel rating you are using will be 12V (or possibly 24V) so parallel connection of the 6 panels is in order.

When run thru an inverter (assuming 100% conversion efficiency and an output voltage of 120V ac) you will get a maximum of 480W and a current of 480W/120V = 4A.

This is far below the 120V 30A supply you mention (which I believe is the service point rating), however when the solar panels are used in conjunction with a battery supply (such as your existing RV trailer battery supply) then you can happily operate your 120V supply off the solar panels (with the batteries supplying any short fall in supply due to clouds or peak loads).

As long as you are not using the oven or any other high current usage devices for long periods of time the system will work fine (and is quite commonly done), the trick is to ensure that your average daily energy usage is LESS than the average daily energy obtained from the solar panels (otherwise your RV batteries will go flat).

Have you tried looking at the RV websites for ideas? A search of "DIF RV solar" produced a number of helpful sites including the following

http://www.siliconsolar.com/rv-solar-panel-kits.html

http://findportablesolarpower.com/diysolarpower/solar-panels/

http://www.solardiy.info/

Based on what you have just said you need to know heaps more than what you seem to know, Ohm's Law is a must inside out!!! coupled with a few other formulas to know where you stand.

Do you really need 30Amp (at 120V) anyway? That's a lot of juice even to get it off the grid let alone from your solar kit that can only supply 5Amp because that'd be, more than likely, at bright sunny day. Some of the things you cannot assume but must be checked. The salesman is definitely not your best option either if you're not sure about technical data.

No offence but this is a serious stuff and unless you know what you're doing, you just end up with a poorly performing something which, more often than not, will give you headache instead of a satisfaction in performance.

Battery types, deep cycle but not gel. This gives a good balance between price and performance. Never use car batteries, they were not designed for such usage and quickly "wilt".....

They should be in an area ventilated to out of your RV, so if when charging any gas is produced, it cannot enter the vehicle, nor can it come near to any ignition areas..... (as with all non sealed LA Batteries.)

If I were doing this for myself, I would make sure that I had good indication of charging/discharging and battery voltage at all times.

I would set up the solar cells to directly charge my batteries, not via an inverter and mains battery charger, with a proper Solar charge controller that would disconnect my mains input when the sun is strong enough to charge and reconnect, when the Sun is gone AND the batteries are mostly discharged.....that way I get the best out of my Solar.....

Do not think that the batteries have to be at 100% charge all the time. In fact with regard to battery life, they need to be "exercised" (not Exorcised!!) regularly to make sure that their "Muscles" flex well.

Do not overcharge above about 13.8 volts (I personally set 13.4 on my caravan) as this will cause gassing and loss of water from the acid....it also speeds up aging of the battery.

recharge when the voltage drops below about 11.8-12 volts. (If using car batteries change this to 12.6 volts.)

This will mean that you will never get to 100% full charge, but the battery will thank you with an extremely long life.....

If you need 100% charge for capacity reasons, then your battery is under dimensioned, it needs to be able to supply your 100% usage with max 70% battery capacity....(sounds complicated but is not really!) just buy a battery with a capacity at least 30% greater than you need. More is better.

Have fun......

B....Good Answer.

Thank you all very much for the input and the direction to other resources.... I see that I need to learn more and do more evaluation of needs and cost effectiveness.

tr

Hi Rubberman:

Your 120V 30amp supply can provide constant 120 X 30 =3600 Joul/sec power.

Now, your 6 solar panel either parallel 18 X 5 X6 = 540 joul/sec power, so it is way under. Or In series, 18 X6 X 5 is the same!

You will need 6 huge panel (or 36 panels)can provide approx. 3600 Joul/sec, that is why we still need gasolin engine auxilary power supply to generate more electric power!

Good luck