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23 Replies
- wbrowningExplorerThanks for the replies guy's great stuff.
- pianotunaNomad IIIHi,
You might ask the same question about the 240 watt panels and wind.
I chose to use angle aluminum on the long sides of my existing panels to stiffen them. Then I used six screws per panel to hold them to the roof. They are strategically located behind other items on the roof so are in a wind shadow to some extent.
In your shoes I might be tempted to sell the existing system and get 3 240 watt panels with a tristar 60 amp mppt controller.
Have you done and energy audit? How big is the battery bank in amp-hours?RFCN2 wrote:
pianotuna - I was adding up the approx 18 amps from my current system to the 30 amps from two 240 watt panels.
I went to the link you gave for solar panels. Are these rugged enough to put on the roof of any RV? Lotta wind up there at 70 mph with 30 mph cross wind. - RFCN2Explorerpianotuna - I was adding up the approx 18 amps from my current system to the 30 amps from two 240 watt panels.
I went to the link you gave for solar panels. Are these rugged enough to put on the roof of any RV? Lotta wind up there at 70 mph with 30 mph cross wind. - michelbExplorer
old guy wrote:
I do not really know the correct answer, but I will say this don't buy the 5 or 30 watt ones from harbor freight as they will NOT do the job
If you are just looking at maintaining the charge while in storage and no load, you don't need much.
We have a 15 years old 5W panel on top of the front A/C unit on the roof of our old gas motor home and it was enough to keep 2 12V + 2 6V fresh over the winter in Ottawa, Ontario, Canada.
Last year I had 2x 7W panels (might be from Harbor Freight) on the roof of our DP and it was enough to keep 2 12v and 4 6V fresh for 4 months in storage in Florida and it was in an area with a lot of shade. - pianotunaNomad IIIHi,
Panels run below $2 per watt in cost. Sounds like someone is doing a pretty high "mark up". Here is one that is a lot cheaper! 12 volt panel
To use a 36 volt system you would need to change to an MPPT controller.
2 240 watt panels is not going to get you to 45 amps. It may get you to a little over 30 amps. Or were you planning to have the old system working in tandem with the new?RFCN2 wrote:
I am about ready to add to my current 2 12volt panel system that has 260 watts and about 16.5 amps max. I can add one 12 volt panel to my existing system for 500 bucks for the panel. Then my 30 amp controller is maxed out.
The guys that put up my solar system 1 1/2 years ago tell me I should go with the new 36 volt systems. The new 240 watt panels are $360 each without install. Does anyone know anything about 36 volt systems vs 12 volt systems? I would have to get another controller, but I figure I can add 2 of the 240 watt 16 amp panels and have 45 amps max output. That should cover all my electric needs except air conditioning. Although I currently have a 2000 watt inverter that should power one air conditioner. - RFCN2ExplorerI am about ready to add to my current 2 12volt panel system that has 260 watts and about 16.5 amps max. I can add one 12 volt panel to my existing system for 500 bucks for the panel. Then my 30 amp controller is maxed out.
The guys that put up my solar system 1 1/2 years ago tell me I should go with the new 36 volt systems. The new 240 watt panels are $360 each without install. Does anyone know anything about 36 volt systems vs 12 volt systems? I would have to get another controller, but I figure I can add 2 of the 240 watt 16 amp panels and have 45 amps max output. That should cover all my electric needs except air conditioning. Although I currently have a 2000 watt inverter that should power one air conditioner. - pianotunaNomad IIIHi wbrowning,
Here is a simple flow chart.
Budget-->Energy Audit-->Battery bank size-->number of watts-->PWM or MPPT.
Here is a link to the rather special spreadsheet that N8GS has created to help size solar battery charging systems!
Solar Spread Sheet N8GS
For a nice explanation of solar, try this link: Golden rules of solar - 300w is getting into the zone where you may want to look at some other installations to discover what will work best for you.
Forum Members Solar Installations With Pics - wbrowningExplorerThanks for the replies we have a 99 Winnebago Chieftain with Cummins engine. I could probably stand to upgrade the inverter also. The factory solar charger is only 10Watts. has anyone upgraded there panel I would like to go 250 or 300. Any good Ideas.
- Golden_HVACExplorerMy RV has a propane and CO detector, and along with the refrigerator, the load on the battery is 35 amp hours per day. THis is about what one 120 watt solar panel will put out in one day.
So I would suggest a 100 - 150 watt solar panel as a start. IF you like to watch TV or other large use of power, install a second or third panel. Make sure to check the area that you plan on installing the panels. Some 200 watt panels can not be installed on any RV roof, there is not enough space for the huge panels.
SunElec.com Look for 100 - 150 watt 12 volt nominal panels. Look for a PWM controller that is rated for a few more amps than the panel.
Fred.
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