Solar PV Panels and Systems

With mobile setups, you can usually charge a few different ways. All of our vans/vehicles have an alternator that powers the accessories and keeps our starting battery charged up. For normal usage, this is all that you need. Once you start adding additional accessories for camping and such we tend to add more batteries and alternate ways to keep them charged.

When adding a house battery, usually you start with the original alternator, then possibly upgrade to a larger alternator(and wiring), with the possibility of adding a secondary alternator, a converter/charger(standard in RV installations), gasoline/propane/diesel generators, and finally my favorite: solar panels.

Solar PV:

Solar PV(photo-voltaic) cells absorb sunlight and produce electricity. A Solar PV panel consists of many solar cells joined together. On a mobile installation like a campervan or recreational vehicle you are generally looking at 12vdc panels(usually ~18vdc at maximum output).

A PV system ends up being a combination of the panel, wiring, junction box, charge controller, and battery bank. Here is an example of how everything might tie together.

With a mobile installation, you want to pay attention to the size of the panels and where you are going to mount them. You do not want ANY shading of the panels from roof vents, racks, air conditioner, vent pipes, etc. Any shading is going to cut down your output quickly and eventually the panels will stop producing.

Heat is another concern, Solar PV panels get HOT, and the hotter they get the less energy they put out. The more airflow the better. Also the closer they are to the vehicle surface, more heat is going to be transferred into the vehicle. Ideally you would have 4 inches of clearance under the panels but in mobile installations that isn't always ideal or even possible. If you use a mounting system that allows for you to tilt the panels, this can improve airflow as well as optimizing absorption(by tilting towards the sun), however, wind load could be an issue. For this reason alone, I would not mount flexible panels to the surface of the vehicle, unless you really want the extra heat. Then again, I wouldn't use flexible panels at all, they just are not yet as refined/reliable as the glass panels. However, in time I am sure that this will change as the flexible panels become more reliable.

Solar panel efficiency commonly found today is usually ~13-20%.

Parts examples:

• GrapeSolar GS-S-160-Fab8 58"x26" 8.65A $199 each, starting with 1, prepared for 2 - discontinued or close to discontinued $190 for a while now out of stock? http://amzn.to/2pi6Gdl

• GrapeSolar GS-STAR-100W $90(currently on sale)+tax https://www.homedepot.com/p/204211365 or https://amzn.to/2JsgLA1

• GrapeSolar GS-Star-180W $230 each+tax http://www.homedepot.com/p/301466985 or http://amzn.to/2qcev9y (currently on sale through the end of May2017 $220 at http://www.homedepot.com/p/301024442)

• CTEK D250S Dual 20A dual input charger MPPT, once house battery is charged, will charge starting battery. $180 http://amzn.to/2pScPB1

• Grape Solar GS-PWM-40BT 40 Amp PWM(not MPPT, so less efficient but cheaper) Solar Charge Controller with Remote Monitoring. $53 http://amzn.to/2pI56Tl

• Renogy 20 Amp MPPT Solar Charge Controller $130 http://amzn.to/2qNGdX6

• Y Branch MC4 Parallel Connector Adapter http://amzn.to/2qafbZj

• MC4 to Bare wire - available in variable lengths and gauge: http://amzn.to/2rJsp0s

• Use some liquid tight cord grips for leak free penetrations through the body https://amzn.to/3icmprI

How much battery should I add for my RV/Camping conversion?

See the batteries page.

Power Inverters: Converting 12vdc to 120vac

I moved this to another page, see the Inverters page.

How much solar can I realistically fit on the roof of an Astro/Safari van?

How much do you want? The max amount will change over time as cells become more efficient. Using the panels above from GS, you can very easily put 2*160watt panels=370watt without any overhang, 3*160=480watt, 4*160=640 or 5*160=800 if you wanted to go super crazy and build the support for it. Off the top of my head, I think the usable roof space was ~105x55(double check that) or somewhere close to that.

Flat mount or tilt?

Yes it makes a difference, though I probably wouldn't want to mess with it unless we were going to spend a lot of time parked in one place. We tend to be more mobile and move every day or 3. For YOUR setup, it may be worth it.

Can a setup like this power an induction cooktop?

Of course it can, but there are a lot of factors. Like which cooktop, what you are cooking, and for how long.

• • 1500watt induction cooktop http://amzn.to/2jsFYxM or this 1650watt one http://amzn.to/2Ai0Y2w

  • 2000watt pure sine wave inverter http://amzn.to/2iY8Qic

  • 1 trailer of batteries, just kidding, but you do need to plan the size of your battery bank based on your needs.

Instead of solar, can I just use my alternator?

Sure you can! If you run the engine enough to keep your battery bank charged up, then you don't need any solar. This is helpful for people that are always moving their vehicle instead of staying in one spot for long periods of time. Just remember that it's a long slow climb to 100% charged when it comes to lead acid batteries.

• • There needs to be a balance between your consumption and your generation.

  • You can easily upgrade your alternator to the AD244, puts out more both at idle and above idle.

  • You can add an second alternator, the forums have some details on this.

  • You can even do both, upgrade your alternator AND add a second one.

Can I power an Air Conditioner with only solar and batteries?

Maybe. It is completely possible to power a small sized AC unit with solar and battery power alone. However, currently mounting enough solar would be difficult and none of it is exactly cheap. It would require quite a bit of battery to run through the night and enough solar to be able to charge the batteries and run the AC unit. As solar/battery/inverter efficiency increases and prices continue to drop, this will get cheaper and easier to do as time goes on. There are so many variables that it is impossible to give exact solutions, so here would be an over-generalized example for about the cheapest for an AC setup that could run 8+hrs without sun. (WIP)

• Small window AC unit, 5000btu units can be had quite cheap, maybe $100-200 if you do some shopping around. There are some new DC powered AC units, but they are extremely expensive. Mini-split units would be next most efficient power wise, but costs and mounting/longevity issues could be a problem as they aren't exactly designed to be mobile, then you have the window AC units, cheap, available and easy to replace. Portable AC units are the least efficient as far as usable BTU output and I would avoid them if at all possible.

• Battery bank: ~600 usable amp hours, really only lithium would fit the bill here for size/weight/longevity/charging. You can get lithium batteries for less than $600 per 100ah these days. ~$3,500 worth of batteries at the time of writing.

• At least 1200watts of solar to charge your batteries and run an inverter. ~$1200 for the panels, depending on brand/etc. Trying to find the space to mount that much solar on our vans you would have to get extremely creative. I have seen side mounted panels, awning trays that slide out from under the top set of panels, portable glass and flexible panels to be deployed as needed and some have even mounted a bunch on a trailer they pull behind them.

• A 3000watt inverter, might be able to get away with a slightly smaller unit, but 3000 is probably the sweet spot if you want to be able to run pretty much anything. $3-400 for an inverter.

• Solar charger, get an MPPT, these can be had relatively cheap and size/price will depend on how much solar you have installed. Some are dual inputs where it can also use your alternator to help with charging. $200-600 depending on many factors.

• Then of course the wiring(and all the bits that go with that), panel and AC mounting, tools if you don't have them, etc. These will vary greatly, but I would budget in at least $300 and up to 'the sky is the limit'.