Minimal Solar Power System

[Randy J.]

My thinking is to minimize the DC power consumption of our old Trillium to mostly just LED lights and then install a minimal solar system (panel, charge controller and a small bottoming cycle battery. The goal would be to be able to mostly recharge the battery during one sunny summer day. We have a 1970s vintage converter but I will probably replace this with a small charger that could charge the batteries and keep the lights on when I'm plugged into the post.

Most of the calculations I find on line seem way more than I need. (A smart-alecky friend with a monster RV suggested we might use solar patio lanterns. Just bring 'em inside at night he says! ).

Seriously though, has anyone else come up with a minimal system? What did you use?

[Carol H]

I started out and still have a simple small 15 watt system. It has worked out well for many many days of dry camping. I have LED bulbs in all lights and I have a 3 way fridge I run on propane. So the lights, water pump & Fantastic Fan are the main power consumers, I have also dry camped in the southern US in the winter, as well as here on the wet coast in the fall and have run the furnace to take the chill off in the morning and just before bed (furnace fan is a big power hog). I never let the battery drop below 11.9 and the small panel will charge the battery right back up in less than half a day in the sun. I also recharge phones and camera off the trailer battery. I dont use any other electrical appliances when dry camping. If I had to run the furnace more than I do then I would need a much bigger panel.

If you dont have a fridge that runs on propane thats a whole different calculation and based on experience of camping with friends with no propane option on their fairly new DC fridges you can never have to many watts- buy the biggest wattage panel you can afford!

[Thomas G.]

Of course, minimal is subjective. I have a 60 watt panel on the roof and a 100 AH battery and it supplies all my needs including a vent fan. I have not used it for long periods with the furnace fan running, but I suspect that the solar panel would be overtaxed rather quickly.

Overall, I think it is a practical plan. The price for solar panels has come down so much that you can install a decent sized panel (like 80+ watts) without breaking the bank.

The flexible panels that Norm links look like an attractive choice.
http://www.fiberglassrv.com/forums/f...tml#post415929

[honda03842]

Tom, The price looks so good I/m thinking about adding another panel.

[Randy J.]

Carol (H.), your system sounds about right for us. Did you buy it as a packaged system or as individual components. Do you mind sharing more details (make, approx. price, where purchased). Thanks.

[stevebaz]

I have 2 small 30 watt pannels hooked together with a large group 27 Walmart deep cycle / starting battery. It charges my battery and runs my fantastic fan, cooling fan for the refrigerator and my heater and my indoor lighting which is all led bulbs and the water pump.
Out west here there is more sun than not and so far I have not camped under the trees. I have no issues with power. I do not conserve power I just use what I want, leave lights on if I want. Battery enters the night at 12.7 volts and at daylight after running the heater and lights through the night will be at 12.4 volts or so. It will be recharged about 4 hours or so. This is a new battery about a year old. I choose the 2 small 30 watt pannels because they fit through my escape hatch and are easy for me to set up on the roof when I need them. I do not have a shower consuming alot of power and my heater is the Attwood II the most efficient fan I could find. Fridge runs on propane.

[Byron Kinnaman]

Originally Posted by Randy J.

My thinking is to minimize the DC power consumption of our old Trillium to mostly just LED lights and then install a minimal solar system (panel, charge controller and a small bottoming cycle battery. The goal would be to be able to mostly recharge the battery during one sunny summer day. We have a 1970s vintage converter but I will probably replace this with a small charger that could charge the batteries and keep the lights on when I'm plugged into the post.

Most of the calculations I find on line seem way more than I need. (A smart-alecky friend with a monster RV suggested we might use solar patio lanterns. Just bring 'em inside at night he says! ).

Seriously though, has anyone else come up with a minimal system? What did you use?

You're on the right track by reducing the amount needed.
We are out and off the grid for about 100 days each winter. Here's what I've done and so far it's worked quite nicely.
All light are LED except the kitchen lights which are 2 12" CCFL tubes. (the CCFL tubes draw slightly more than the LED lights.)
The furnace does run a bit. We set the thermostat at 55° at night.
Battery 80 amp hour deep cycle. A secondary battery for ham radio is a 50 Amp hour Gel Cell.
Solar Panel 65 Watt (Kyocera KC65T) Approximately 4 amp of charging current.
Charge controller..Morningstar's SunSaver (SS6)

I made a stand attached to the solar panel and pocket in the back of the truck for it to travel in. About 50' of cord allow me to move into direct sun when I use it.

This has worked great 5 or 6 years for us.

[Thomas G.]

Originally Posted by Randy J.

Carol (H.), your system sounds about right for us. Did you buy it as a packaged system or as individual components. Do you mind sharing more details (make, approx. price, where purchased). Thanks.

I think you may regret going with only 15 watts, especially given how much the price of solar panels have dropped.

Check out the prices on these rigid panels.

Solar Cell, Solar Panel, Renewable Energy, Wind Energy, Charge Controller, Solar Trackers - Solar Cell, Solar Panel, Solar PV, Solar Products, Charge Controllers, Solar Trackers

[Carol H]

Originally Posted by Randy J.

Carol (H.), your system sounds about right for us. Did you buy it as a packaged system or as individual components. Do you mind sharing more details (make, approx. price, where purchased). Thanks.

I purchased it complete with the panel and controller and wiring from a local shop here in Vancouver but the company that made it is no longer offering it but the down side is I paid about $200 (maybe more) for a 15 w panel about 6 years ago. As others have said the price of solar has dropped a great deal in recent years and today I could buy a complete 120 watt system for less than I paid for my system. Systems that come as a complete package do tend to be pricier than if you buy from a specialized solar company the various parts needed.... actually need only the panel and controller and wire connections (but many companies through those in with the controller). The 120 watt system today is also not much bigger in size either. If I was starting from scratch due to the price drops I would look for one that was at least 80 watts which should be enough to cover all your needs. Having said that I have a nephew who only has a 5 watt panel on a *large* toy hauler/trailer combo and he gets by fine with that (as long as its sunny) only powering LED lights and water pump.

Solarblvd.com has some good prices on panels & controllers.

Costco also sells complete kits but much pricer.

[Randy J.]

Thanks everyone, that gives me a better perspective. Prices being down make more-power more tempting but the lights only option as you say needs almost nothing these days. I need to make a decision on appliances before final sizing. My next step is to have a technician have a look at the appliances we have. Not sure we need that big furnace in our little 13 ft - maybe a cat for those rare off-grid times we need anything. The old three-way is tempting to keep, especially if it is found in good condition. But apparently the DC function on those has only limited use anyway (i.e. between campsites when it is already cold) so it may not be a big consideration.

[Roy in TO]

Something to keep in mind is that the newer technologies allow for smaller panels. I think I got a single 80W panel that is much smaller than my 3 x 15W Coleman (AKA Canadian Tire) kit. Same for price, I got more for less.

[Roy in TO]

Originally Posted by Randy J.

We have a 1970s vintage converter but I will probably replace this with a small charger that could charge the batteries and keep the lights on when I'm plugged into the post.

I'm thinking of doing the same, right now I just bring along the battery charger I keep in the garage.
Ideally I'd like to find an all in one unit. A small converter, a smart battery charger and solar controller, all in one unit. I have a few jobs to do first, so this will be a year or two down the road.
Let us know what you find.

[Roy in TO]

Randy,
David Tilston just gave me a heads up on a 40W system on sale for $100 in today's Canadian tire flyer. Reg. $250.

The price shows regular online, not sure if there is a price correction in the stores. If not this is a great deal you can pick up locally.
Coleman 40W Folding Solar Panel | Canadian Tire

[Jon Vermilye]

Off The Grid Solar is putting together a $395.00 & free shipping to the lower 48 states group buy for their 90 watt kit (includes controller, wiring & is a "suitcase" system) for members of the Casita Travel Trailer forum. They will start shipping when the number of orders reaches 10.

You probably have to join the Casita Trailer Forum to view the page, but it is a useful forum for anyone owning a fiberglass trailer. If you don't want to join the forum, you might try contacting the company & see if you can still participate.

[Thomas G.]

Some interesting kits offered on eBay. Here is a 120 watt one for $290, with free shipping, supposedly from California.

120W Folding Solar Panel Kit Battery Charger Car motorhome Caravan Boat Camping | eBay

[DrewSK]

I just got a 100W kit from amazon for $210. We left for a week-long excursion to Colorado with the battery around 12.3V, and with our lights, water pump, and fantastic fan use- the battery was fully charged by the time we headed home. This was with the panel is mounted flat on the roof. Solar panels really are getting incredibly affordable.

[tartosuc]

What is the wattage of original the uhaul solar panel?
I have good performance from that old panel running led lights and fans in my egg...

[Thomas G.]

Originally Posted by tartosuc

What is the wattage of original the uhaul solar panel?
I have good performance from that old panel running led lights and fans in my egg...

I calculated it once based on area and the fact that it is amorphous technology. But I've forgotten. My best guess is 10 watts or less. You can repeat my calculation if you measure it.

An Introduction to Photovoltaic Systems | GreenBuildingAdvisor.com

Polycrystalline PV arrays have a peak rating of 10 to 12 watts per square foot, while amorphous PV arrays have a peak rating of 5 to 6 watts per square foot.

When I measured my original panel, the output was almost zero - I guess due to age. This was done while by passing the controller.

[tartosuc]

If you dont have a fantastic fan already(wich is very expensive in my opinion)
You could use a solar vent like the sunforce...

[David Tilston]

Originally Posted by Roy in TO

Randy,
David Tilston just gave me a heads up on a 40W system on sale for $100 in today's Canadian tire flyer. Reg. $250.

The price shows regular online, not sure if there is a price correction in the stores. If not this is a great deal you can pick up locally.
Coleman 40W Folding Solar Panel | Canadian Tire

I bought two @ $100 / each. One for the 18 year old, one for me. They are in the regular flyer now. It comes with a cheep charge controller big enough for two cells, in parallel. What struck me was the size. They are poly crystalline arrays, so I expected them to be bigger. The dimensions are D 37.5" x W 14.5" x H 2". With some hinges, two cells could make an excellent 80W fold up array. Only one day left.
What I saw yesterday though, Costco has their 6V golf cart batteries for $79. Two of those would make 240 Ahrs @ 12 V. That is a substantial amount of power. At half discharged, the two solar cells from Canadian Tire, in full sun, would take 26 hrs to charge 120 Ahrs.