UPDATE – we have a new improved solar system!  Check it out here: 600 Watts of Affordable RV Solar

One question we get often is “what all can be powered by solar panels on an RV?”  The question is simple, the answer…well, it’s a bit more complicated.

First, let’s look at the RV Solar Power set up we have on Windy:

I know that was quick and brief but hopefully it gives you an idea of what our set up looks like and how it works.  As you see we have two 65 watt solar panels for a grand total of 130 watts.  Our solar power setup isn’t perfect and can be improved providing more power.  That said we’re happy with our purchase as it does allow us to live off the cord longer (without having to run the generator) than the standard RVer.

solar panel

This solar setup was pretty basic.  We had it installed at the Monaco factory when we picked up Windy in February 2011.  The cost was $3,000.00 for the 2 panels, a charge controller and remote meter.  The cost for install was $1000.00.  The grand total as you see in the video is $4,000.00

By no means are we solar pros, so we called on Clay the “Solar Guru” over at The Power Company to help give you an idea of the perfect solar setup for 3 types of RVers:  Basic, Medium and Heavy use.

We met The Power Company guys at Burning Man and they are hard core energy saving fools!  They had the most amazing, and efficient, RV Solar set ups we have ever seen.  At Burning Man these guys were able to power an entire bar off the sun including a bumpin’ stereo, blenders, refrigerators, draft beer pumps, disco lights, and everything else you can image in a Burning Man style bar.  So, let’s get technical, and get you ‘solared’ out!  (just to clear the air this is not a paid post, the power company didn’t compensate us for this.  These are nice guys we met on the road who are doing cool things with solar power, and we felt the RV community needs to meet them!)

The Basic RV Solar Setup

Basic: I want to power lights, run my fantastic fan and keep my house batteries charged while I am dry camping.Solar Guru Recommends: 12 volt Basic System; 55 watt module, charge control, 25’ module cables, 10’ battery cables, fuses, fuse holders, solder-less connectors and a simple module mount, (mount to roof fasteners not included).Average use per day rating – 220 watt hoursCost – $478.00 (Nevada addresses add $25.65 sales tax.) (Battery Bank Not Included)

Medium Use RV Solar Setup

Medium: I want to power lights, run my fantastic fan, charge my cell phones, laptop and watch 2 hours of TV a day.Solar Guru Recommends: 12 volt Medium System; 2 – 140 watt modules, charge control, 25’ module cables, 10’ battery cables, fuses, fuse holders, solder-less connectors and a simple module mount, (mount to roof fasteners not included).Average use per day rating – 1120 watt hoursCost – $1,175.00 Nevada addresses add $75.00 sales tax. (Recommend 200 AH Battery Bank as a minimum. Not Included)If you don’t have a 12 volt TV you will need an inverter, add $1020.00 for 1100 watt pure sine inverter. Nevada addresses add $66.31 sales tax.

Includes 10’ battery cable with pre crimped ends and circuit breaker. AC output needs to be connected in safe way. Contact for example diagrams.

Crazy Heavy Use RV Solar Setup

Heavy: I want to power lights, run my fantastic fan, charge my cell phone, laptop, use an electric kettle, run my electric blender, run the microwave for 5 min and watch 2 hours of TV a day.Solar Guru Recommends: 12 volt Heavy Duty, (and we mean Heavy Duty) system; 6 – 140 watt modules, charge control, 25’ module cables, 10’ battery cables, fuses, fuse holders, 2000 watt pure sine inverter / charger, AC hook up wire, remote inverter controller, load center with breakers for inverter and charge control, charge control battery temperature sensor and simple module mount, (mount to roof fasteners not included).Average use per day rating – 3360 watt hoursCost – $12,708.00 Nevada addresses add $900.13 sales tax. (Recommend 600 AH minimum battery bank, not included.)


Notes from the Solar Guru — All prices include a 10%, “Gone With the Wynn’s Discount” and shipping to most locations, (example – southwest states and a couple midwest states.) Be sure to mention the Wynn’s when contacting us!  ***You will need additional pieces and parts to complete your installation.  If you need help installing these systems we can come to you or you can come to us. Contact us for more information.

Are we confused yet?  Nobody said going solar was easy to understand.  To put all this in layman’s terms is practically impossible.  What you need to understand about solar is that it’s a science that has a million variables based on sun, daylight hours, and quality of your products, battery age, and so many other factors.  Below we try to break it down a little further, but I can’t promise it will make you any less confused.  The best thing you can do is call in and discuss with the pros.  In the meantime we’ll try to un-confuse ourselves below:

A Little More Detail on Solar Power

Watts example: A standard incandescent 12 volt RV light fixture uses 1 or 2 – 18 watt bulbs. If 1 bulb is used, and you had the basic system, you could run that 1 bulb for 12 hours just from the energy harvested from the module.As in the basic system, the average daily output is based on the solar module being the only input you have. So one could use 220 watt hours from dawn to dawn and be ok, mostly. There are many other variables to this, but for ease of understanding, this will get the job done.Ohms Law;amps x volts = wattswatts x hours = watt hours

Example: 55 watt module x 5 hours of clear day sunlight = 275 watt hours. If the module is flat x .8 for realistic output.

Batteries: Most are rated in Amp Hours; this is not a good way to measure usage or storage. Watt hours is more accurate as a guideline, Amp Hours of the battery x the nominal voltage of the battery. Example: 200 amp hour x 12 volts = 2400 watt hours. You don’t want to take %100 of the storage, so figure %50. Batteries can only be recharged a finite number of times, the more you take, the less times you can recharge them. SO, if you use 100 watt hours from dawn to dawn and you have 220 watt hours of solar input, it will take .46 hours to put that back into the batteries from that 55 watt module. Basically.

The hardest part of this is figuring out how long you will REALLY run the loads you want to power, then finding the amps or watts of 12 volt items to figure it out.

Lot’s of people will say, “no one needs more than XX watts of solar; we dry camp all weekend and don’t have a problem!”. The solar guru explains that most of the time under sized systems just slow down the discharge of their battery bank. Which is fine for a weekend maybe, but the batteries are usually depleted when they are leaving. Most RV’s will charge the batteries while underway, so no one really notices.


One of our readers shared this very detailed breakdown of the Solar RV Setup for their Safari Trek. The information goes in depth (and I mean in depth) on the science behind solar in different lattitudes, months, usage numbers for appliances, battery capacity, and so on. It’s a very interesting read and a must if you’re planning to do a solar installation on your RV.

Safari Trek RV Solar Design and Setup

The Trek RV Solar System Design and Operation
Revised: May 7, 2010An RV Solar System design is different from a residential system in two ways: first, real estate for mounting the panels is limited; and two, the position of the sun relative to the RV panels change with each new location. This implies that components need to be chosen for their ability to wring the maximum energy from the sun during daylight hours. Fortunately, technology in the three critical areas of battery, solar panels, and solar controllers has come a long way in the last few years. But there will still be some lifestyle and operational tradeoffs.The design begins with a determination of our daily power use that is compatible with the limitations of the RV’s battery and solar charging capabilities. Necessarily, that will imply a certain lifestyle … which may cause the numbers to change from time to time.Electrical Item Qty Watts hrs/day Whrs/day
AC Inverter Loads
Coffee Maker 900 0.5 450
Toaster Oven 1300 0.1 130
Sharp Conv/Micro 850 0.17 144.5
Total Cooking 724.50Internet
Hughes Modem 19.2 2.0 38.4
LinkSys Wireless 8.5 2.0 17
Lynn Laptop 34 2.0 68
Dick Notebook 25 2.0 50
Total Internet 173.40

Television
Dish Vip612 DVR 45 2.0 90
Sharp 26” LCD 115 2.0 230
Sony DVD/CD 10 1.0 10
Magnedyne Sound 100 3.0 300
Wii Exerciser 45 1.0 45
Misc. Chargers 18 2.0 36
Total TV 711.00

DC Battery Loads
Furnace Fan 91 1.0 91
Safety Detectors 3 1.2 24 28.8
Fantastic Fans 2 2.4-23 6 240
Water Pump 48 0.5 24
Bed/Awning Motor 2 96 0.12 23.04
Total DC 406.84

Lighting
Ceiling F15T8 2 15 2 60
Galley F8T5 2 8 4 64
Bath 1141 3 18 0.5 27
Bed 1141 6 18 0.5 54
Dinette 921 16.8 2.0 33.6
Clip-On 13 CFL 13 2.0 26
Total Lighting 264.60

Total Sys Whr/Day 2280.34

The tabular DC Ahr = 2280.34/12 = 190.03 Ahrs. Using a factor of 1.5 for losses resulting from a poor power factor, copper transmission, & inverter/charger losses, the total requirement for the battery charging system is 285 Ahrs/day.

Our Safari Trek Motorhome, at 29’, is shorter than many suggesting limited space for the installation of solar panels. This implies the use of high efficiency solar panels placed in a way that minimizes shading by roof components such as the air conditioner, roof vents, and TV antenna. If just a few cells of a solar panel are shaded, it can significantly reduce the panel’s power … in some cases, it can reduce panel power to zero.

The Trek’s electrical system is optimized around a Magnum 2000W inverter/charger. The charger efficiency is 85% with a 100A maximum for charging the batteries. The charger’s power factor (pf) is greater than 0.95. This implies a 1 to 2 hour generator-produced bulk charging cycle to achieve an 80% capacity. Absorption (3 hours) and equalization (2 hours) cycles would require an additional 5 hours (solar or shore power). When batteries are chronically undercharged, plate sulfation develops to reduce both capacity and battery life.

The Magnum’s inverter produces a modified sine wave with an efficiency of 94% max (at 2000W output). Unfortunately, the modified sine wave produces eddy current resistance losses for all AC inductive loads (transformers and motors). Most AC loads are inductive with power factors varying from 0.45 to 0.9.

The Trek’s battery capacity is sized at 440 Ahr (4-AGM 6V 220 Ahr batteries) to be compatible with the 2000W inverter/charger. Since the tradeoff between battery life and deep cycle performance is dependent on initiating the charging cycle at the 50% discharge level (a battery resting voltage of 12.2), the usable capacity of the battery bank is limited to 220 Ahrs. One of the nice things about a solar system is that it is constantly providing power so that the 50% discharge level takes longer to reach than otherwise.

From the above chart, a charging cycle of approximately 285 Ahrs will be required, where the bulk charging cycle is done by the generator, while the much longer absorption and equalization cycles are done by the solar array.

A 285 Ahr usage implies a daily/weekly lifestyle consisting of:

1. A continental breakfast (coffee and a muffin)
2. Morning and evening lights for dressing/shaving/reading
3. Daytime activities while the solar array charges the batteries
4. Two hours of evening satellite internet
5. An hour of home-theater radio sometime during the day
6. Two hours of evening TV
7. Three movies a week
8. Cooling and air movement using windows with the Fantastic Fans
9. Miscellaneous housekeeping power requirements
10. Minimal cooking for lunch (sandwiches) and dinner (Wheaties). Of course, we’ll eat out occasionally.

Solar panel requirements are dependent on knowing the available “peak sun hours” during which the panel can be expected to deliver its rated power. Peak sun, defined as 1000 W/m2, varies by season and latitude for any particular location. Data for maps and charts are provided by NASA [http://www.solarpanelsplus.com/solar-insolation-levels/]. For example, in June, the average insolation in Portland, Oregon, is 6.09 kWhr/meter2/day, whereas the June insolation in Anchorage, Alaska, is 4.58 kWhr/meter2/day. Using the above definition, the peak sun hours for those two examples would are 6.09 hours for Portland, and 4.58 hours for Anchorage … assuming cloudless days with the panels directly facing the sun. Thus, a 150W panel located in Portland, Oregon, could supply 913.5 Whrs (76.13 Ahrs) on an average June day.

Regarding the technology of the mono-crystalline silicon solar cells used in our 150 W panels, each cell has an efficiency of 16% – 17% and generates between 30 mA and 35 mA of current per cm2 at a voltage of 550 mV during peak sun hours. Since the cells have an effective area of 225 cm2, the rated current density is 7290mA/225cm2 = 32.4 mA/cm2.

Our 40-cell panels are rated at 20.6 volts at a current of 7.29 amps (150.17 Watts). The rated output of all four panels is then 600 watts, which for 6 peak-sun hours = 3600 watt-hrs/day. For a 12V system, this is equivalent to 300 Ahrs/day (best case, where pf = 1.0).

The 45A TriStar MPPT solar array controller will be configured to use these values to dynamically adjust the load so the maximum power is always transferred, regardless of the variation in lighting. This effectively extends the hours of usable sunlight, and to some extent compensates for cloudiness, shading, and panel orientation.

MPPT is an industry standard acronym for Maximum Power Point Tracking, which allows the use of more cells (higher panel voltage) for lower cell currents (smaller cell size) to produce a better form factor for RV roofs. For example, a panel rated at 150 Watts can use either 40 cells (20.6 Volts) each rated at 7.29 Amps, or 36 cells (18.54 Volts) rated at 8.09 Amps. With MPPT, a panel voltage 6V above the battery level provides better charging management.

Charging Notes:

1. The Lifeline, GPL-4CT, AGM battery bank, consisting of four 6V 220 Ahr batteries (440 Ahr total), has a maximum rated charging current of 132 amps (@ 12V) for the bulk charging cycle.
2. While the total power requirement is 190 Ahr/day, the necessary replacement power will be 50% higher so that the motorhome charging system, consisting of a generator and solar array, actually needs to generate about 248 Ahrs/day.
3. Both the Magnum charger and the TriStar MPPT Controller are capable of all four battery charging cycles of bulk, absorption, float and equalization. For the MPPT, all four cycles are temperature compensated with battery sensing for accurate charging.
4. The Magnum Charger requires either shore power or the Onan 5500W generator to produce a maximum of 100 amps continuous charging current. When ‘peak sun’ is available, the TriStar controller is capable of producing a maximum of 29.16 Amps. Thus a maximum of 129 Amps is available if both are operating at the same time.
5. Bulk charging is when the charging current is constrained only by limits of the charging system. During bulk charging the voltage slowly rises from its 50% depleted level (12.2 volts), to its absorption level of 14.2 – 14.4 volts. To replace 80% of 248 Ahrs at a rate of 129 Amps will require a minimum of 1.9 hours.
6. Once the absorption voltage level is reached, the MPPT controller maintains that voltage while the current is slowly decreased over a period of three hours. At that point the MPPT’s float setpoint voltage of 13.2 – 13.4 volts is maintained indefinitely.
7. The actual voltages for absorption and float depend on the ambient temperature. Lower temperatures require higher charging voltages and vice versa.
8. The basic concept of a three phase charging cycle is to charge the batteries as fast as possible without producing explosive hydrogen and oxygen which, for a 12V battery, happens at the critical gassing voltage of 14.9 – 15.1 volts.
9. Unfortunately this three-phase solar charging cycle won’t be able to charge the battery completely. To complete the chemical process that completely recharges a battery the electrolyte must reach 104° F. If insufficient charge is applied to bring the electrolyte to this temperature the batteries will never fully recharge, and over time, both capacity and life will be reduced due to the formation of sulfation crystals. To recover lost capacity and to prolong battery life, an equalization cycle is periodically required to use a higher voltage to level the cell voltages and to complete the chemical reactions. The TriStar MPPT controller can automatically execute a two hour equalization cycle at 15.1 volts every 28 days. The Magnum charger is not used for equalization.
10. Typically the generator will run from one to two hours to do the bulk charging, while the solar array will finish with an absorption charge of three hours followed by a float charge for two more hours. The result will be a charged battery that only requires an occasional equalization cycle.
11. Besides providing 100 Adc for the Magnum inverter (10Aac), the Onan 5.5kW generator is also able to provide AC power to the coach for other tasks, such as air conditioning, hot water heating, refrigeration, and other wall-socket loads. Like most electrical power devices, the generator is more efficient when run at 60% or better of rated load.
12. A future useful upgrade would be a sine wave Magnum Inverter rather than the present modified sine wave. The increased cost is approximately 20%, but both system efficiencies and power factor will be significantly improved to result in reduced charging times.
13. For completeness it should be noted that energy for the coach furnace, refrigerator, 3-burner cooktop and hot water heater are all supplied by propane. Both the furnace and the refrigerator require a small amount of DC for the control circuits.

http://www.solarpanelsplus.com/solar-insolation-levels/

Solar Insolation Levels In North America (kWh/m2/day)
Insolation (Incoming Solar Radiation) is the amount of solar radiation incident on any surface – for our purposes, we will be comparing insolation levels on the surface of the Earth. The amount of insolation received at the surface of the Earth is controlled by the angle of the sun, the state of the atmosphere, altitude, and geographic location.
The values of solar insolation are commonly expressed in kWh/m2/day. This is the amount of solar energy that strikes a square meter of the earth’s surface in a single day.

Insolation levels are used to determine what size solar collector is needed to efficiently provide adequate levels of hot water. Geographic locations with low insolation levels require larger collectors than locations with higher insolation levels.
For comparison, consider the average annual insolation levels of these two extreme locations:
• Oslo , Norway = 2.27 kWh/m2/day (very low)
• Miami , Florida = 5.26 kWh/m2/day (very high)
See a solar insolation map or use the solar calculator.
State City Latitude Longitude Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year Avg
AL Birmingham 33′ 34″ N 86′ 45″ W 2.29 3.31 4.04 5.14 5.92 5.98 5.81 5.7 4.8 3.93 2.96 2.25 4.34
AK Anchorage 61′ 10″ N 150′ 1″ W 0.21 0.76 1.68 3.12 3.98 4.58 4.25 3.16 1.98 0.98 0.37 0.12 2.09
AR Little Rock 32′ 25″ N 94′ 44″ W 2.36 3.39 4.01 5.32 5.71 6.19 6.15 5.85 5.25 4.17 2.95 2.25 4.46
AZ Phoenix 33 ‘ 26″ N 112′ 1″ W 3.25 4.41 5.17 6.76 7.42 7.7 6.99 6.11 6.02 4.44 3.52 2.75 5.38
CA Los Angeles 34′ N 118′ W 3.09 4.25 5.09 6.58 7.29 7.62 7.45 6.72 6.11 4.42 3.43 2.72 5.4
CA San Francisco 38′ 31″ N 121′ 30″ W 2.35 3.33 4.42 5.95 6.84 7.39 7.55 6.51 5.75 3.92 2.65 2.06 4.89
CO Denver 39′ 45″ N 104′ 52″ W 2.25 3.2 4.32 5.61 6.11 6.71 6.5 5.86 5.47 4.01 2.59 1.98 4.55
CT Hartford 41′ 44″ N 72′ 39″ W 1.7 2.43 3.48 4.07 5.14 5.58 5.38 5.04 4.13 2.91 1.81 1.42 3.59
DE Dover 39′ 8″ N 75′ 28″ W 1.85 2.62 3.6 4.33 5.44 5.91 5.64 5.3 4.38 3.23 2.21 1.66 3.84
FL Miami 25′ 48″ N 80′ 16″ W 3.72 4.61 5.42 6.4 6.61 6.29 6.26 6.08 5.47 4.84 3.96 3.46 5.26
GA Atlanta 33′ 39″ N 84′ 26″ W 2.31 3.37 4.08 5.2 6.02 6.01 5.81 5.59 4.76 3.95 2.98 2.33 4.37
HI Honolulu 21′ 20″ N 157′ 55″ W 4.38 5.15 5.99 6.69 7.05 7.48 7.37 7.07 6.51 5.46 4.41 4.01 5.96
IA Dubuque 42′ 24″ N 90′ 42″ W 1.64 2.58 3.34 4.57 5.54 6.06 5.81 5.26 4.33 3.03 1.72 1.35 3.77
ID Boise 43′ 34″ N 116′ 13″ W 1.73 2.72 3.77 5.22 5.9 6.57 7.17 6.12 5.28 3.29 1.74 1.46 4.24
IN Indianapolis 39′ 44″ N 86′ 17″ W 1.67 2.59 3.28 4.67 5.46 6.11 5.79 5.37 4.76 3.33 1.97 1.46 3.87
IL Chicago 41′ 53″ N 87′ 38″ W 1.5 2.45 3.2 4.48 5.56 6.07 5.68 5.27 4.51 3.07 1.69 1.26 3.72
KS Kansas City 39′ 12″ N 94′ 36″ W 2.06 2.89 3.62 4.92 5.58 6.17 6.21 5.59 4.9 3.49 2.2 1.75 4.11
KY Louisville 38′ 11″ N 85′ 44″ W 1.71 2.65 3.32 4.73 5.38 6.08 5.79 5.35 4.8 3.42 2.1 1.56 3.9
LA New Orleans 29′ 37″ N 90′ 5″ W 2.64 3.73 4.67 5.8 6.6 6.15 6.09 5.7 5.13 4.48 3.49 2.68 4.76
MA Boston 42′ 22″ N 71′ 2″ W 1.66 2.5 3.51 4.13 5.11 5.47 5.44 5.05 4.12 2.84 1.74 1.4 3.58
MD Annapolis 38′ 35″ N 76′ 21″ W 1.96 2.8 3.71 4.55 5.54 6.03 5.77 5.34 4.48 3.4 2.37 1.81 3.98
ME Portland 45′ 36″ N 122′ 36″ W 1.38 2.33 3.49 4.57 5.46 6.09 6.64 5.78 4.8 2.79 1.41 1.1 3.82
MI Detroit 42′ 25″ N 83′ 1″ W 1.43 2.33 3.19 4.34 5.44 5.98 5.64 4.99 4.25 2.73 1.52 1.14 3.58
MO St.Louis 38′ 45″ N 90′ 23″ W 2.02 2.82 3.52 4.97 5.56 6.21 6.05 5.63 4.91 3.55 2.21 1.73 4.09
MN Minneapolis 44′ 53″ N 93′ 13″ W 1.6 2.61 3.3 4.55 5.44 5.86 5.77 5.12 4.12 2.9 1.62 1.34 3.68
MS Jackson 42′ 16″ N 84′ 28″ W 1.47 2.41 3.22 4.33 5.46 5.93 5.57 4.99 4.3 2.78 1.55 1.17 3.59
MT Billings 45′ 48″ N 108′ 32″ W 1.55 2.57 3.52 4.82 5.63 6.45 6.39 5.75 4.67 3.19 1.77 1.3 3.96
MT Great Falls 43′ 33″ N 96′ 42″ W 1.3 2.36 3.41 4.84 5.56 6.18 6.44 5.53 4.4 2.9 1.53 1.11 3.79
NC Charlotte 35′ 13″ N 80′ 56″ W 2.22 3.17 3.95 4.98 5.8 6.01 5.76 5.27 4.58 3.75 2.76 2.21 4.2
ND Fargo 46′ 54″ N 96′ 48″ W 1.44 2.39 3.36 4.79 5.62 5.82 5.94 5.14 4.01 2.83 1.59 1.31 3.68
NE Omaha 41′ 18″ N 95′ 54″ W 1.92 2.76 3.45 4.74 5.6 6.14 6.11 5.46 4.74 3.34 2 1.57 3.98
NH Manchester 42′ 56″ N 71′ 26″ W 1.66 2.5 3.51 4.13 5.11 5.47 5.44 5.05 4.12 2.84 1.74 1.4 3.58
NJ Trenton 40′ 13″ N 74′ 46″ W 1.71 2.39 3.43 4.04 5.26 5.67 5.39 5.14 4.18 3 1.98 1.48 3.63
NM Albuquerque 35′ 3″ N 106′ 37″ W 2.92 3.97 4.92 6.3 6.68 6.94 6.66 5.8 5.68 4.18 3.16 2.5 4.97
NV Las Vegas 36′ 18″ N 115′ 16″ W 3.02 4.13 5.05 6.57 7.25 7.69 7.37 6.42 6.08 4.26 3.18 2.6 5.3
NY New York 41′ N 74′ W 1.67 2.37 3.41 3.93 5.11 5.48 5.26 5.01 4.05 2.85 1.82 1.4 3.53
OH Columbus 39′ 16″ N 85′ 54″ W 1.64 2.57 3.26 4.63 5.4 6.08 5.73 5.29 4.74 3.29 1.96 1.45 3.83
OK Tulsa 36′ 12″ N 95′ 54″ W 2.33 3.22 3.9 5.25 5.58 6.32 6.4 5.8 5.08 3.8 2.62 2.06 4.36
OR Portland 45′ 32″ N 122′ 40″ W 1.38 2.33 3.49 4.57 5.46 6.09 6.64 5.78 4.8 2.79 1.41 1.1 3.82
PA Philadelphia 39′ 53″ N 75′ 15″ W 1.85 2.62 3.6 4.33 5.44 5.91 5.64 5.3 4.38 3.23 2.21 1.66 3.84
PA Pittsburgh 40′ 27″ N 79′ 57″ W 1.59 2.4 3.26 4.07 5.05 5.53 5.27 4.94 4.05 2.88 1.86 1.41 3.53
RI Providence 41′ 44″ N 71′ 26″ W 1.7 2.46 3.53 4.2 5.17 5.67 5.48 5.08 4.21 2.97 1.8 1.43 3.64
SC Columbia 38′ 58″ N 92′ 22″ W 2.14 2.91 3.62 5.03 5.56 6.22 6.13 5.64 4.95 3.57 2.25 1.82 4.15
SD Sioux Falls 45′ 27″ N 98′ 25″ W 1.72 2.71 3.31 4.65 5.61 6.1 6.04 5.42 4.47 3.2 1.78 1.43 3.87
TN Nashville 36′ 7″ N 86′ 41″ W 1.94 2.9 3.54 4.76 5.57 5.9 5.86 5.62 4.63 3.53 2.45 1.82 4.04
TX San Antonio 29′ 32″ N 98′ 28″ W 2.57 3.7 4.43 5.54 5.94 6.62 6.49 6.28 5.7 4.67 3.43 2.62 4.83
TX Houston 29′ 59″ N 95′ 22″ W 2.47 3.5 4.4 5.59 6.03 6.45 6.36 6.07 5.46 4.61 3.3 2.44 4.72
UT Salt Lake City 40′ 46″ N 111″ 52″ W 2.23 3.15 4.09 5.57 6.26 6.98 6.86 5.98 5.39 3.68 2.29 1.97 4.53
VA Washington 38′ 51″ N 77′ 2″ W 1.95 2.8 3.66 4.46 5.42 5.88 5.63 5.22 4.38 3.36 2.34 1.79 3.9
VT Montpelier 44′ 16″ N 72′ 35″ W 1.58 2.54 3.5 4.05 5 5.24 5.37 4.92 3.79 2.46 1.52 1.28 3.43
WA Seattle 47′ 32″ N 122′ 18″ W 1.14 2.04 3.23 4.26 5.19 5.75 6.27 5.46 4.43 2.5 1.21 0.9 3.53
WI Milwaukee 42′ 57″ N 87′ 54″ W 1.43 2.41 3.29 4.48 5.6 6.09 5.74 5.21 4.34 2.9 1.6 1.2 3.69
WV Charleston 38′ 22″ N 81′ 36″ W 1.75 2.64 3.34 4.26 5.2 5.67 5.49 5.19 4.26 3.19 2.15 1.62 3.73
WY Casper 42′ 55″ N 106′ 28″ W 1.93 2.8 3.79 5.13 5.9 6.68 6.5 5.9 5.13 3.59 2.06 1.65 4.25

Peak Sun Hours per Day

http://www.solar4power.com/solar-power-insolation-window.html

State City High Low Avg State City High Low Avg
AK Fairbanks 5.87 2.12 3.99 MO Columbia 5.50 3.97 4.73
AK Matanuska 5.24 1.74 3.55 MO St. Louis 4.87 3.24 4.38
AL Montgomery 4.69 3.37 4.23 MS Meridian 4.86 3.64 4.43
AR Bethel 6.29 2.37 3.81 MT Glasgow 5.97 4.09 5.15
AR Little Rock 5.29 3.88 4.69 MT Great Falls 5.70 3.66 4.93
AZ Tucson 7.42 6.01 6.57 MT Summit 5.17 2.36 3.99
AZ Page 7.30 5.65 6.36 NM Albuquerque 7.16 6.21 6.77
AZ Phoenix 7.13 5.78 6.58 NB Lincoln 5.40 4.38 4.79
CA Santa Maria 6.52 5.42 5.94 NB N. Omaha 5.28 4.26 4.90
CA Riverside 6.35 5.35 5.87 NC Cape Hatteras 5.81 4.69 5.31
CA Davis 6.09 3.31 5.10 NC Greensboro 5.05 4.00 4.71
CA Fresno 6.19 3.42 5.38 ND Bismarck 5.48 3.97 5.01
CA Los Angeles 6.14 5.03 5.62 NJ Sea Brook 4.76 3.20 4.21
CA Soda Springs 6.47 4.40 5.60 NV Las Vegas 7.13 5.84 6.41
CA La Jolla 5.24 4.29 4.77 NV Ely 6.48 5.49 5.98
CA Inyokern 8.70 6.87 7.66 NY Binghamton 3.93 1.62 3.16
CO Granby 7.47 5.15 5.69 NY Ithaca 4.57 2.29 3.79
CO Grand Lake 5.86 3.56 5.08 NY Schenectady 3.92 2.53 3.55
CO Grand Junction 6.34 5.23 5.85 NY Rochester 4.22 1.58 3.31
CO Boulder 5.72 4.44 4.87 NY New York City 4.97 3.03 4.08
DC Washington 4.69 3.37 4.23 OH Columbus 5.26 2.66 4.15
FL Apalachicola 5.98 4.92 5.49 OH Cleveland 4.79 2.69 3.94
FL Belie Is. 5.31 4.58 4.99 OK Stillwater 5.52 4.22 4.99
FL Miami 6.26 5.05 5.62 OK Oklahoma City 6.26 4.98 5.59
FL Gainesville 5.81 4.71 5.27 OR Astoria 4.76 1.99 3.72
FL Tampa 6.16 5.26 5.67 OR Corvallis 5.71 1.90 4.03
GA Atlanta 5.16 4.09 4.74 OR Medford 5.84 2.02 4.51
GA Griffin 5.41 4.26 4.99 PA Pittsburg 4.19 1.45 3.28
HI Honolulu 6.71 5.59 6.02 PA State College 4.44 2.79 3.91
IA Ames 4.80 3.73 4.40 RI Newport 4.69 3.58 4.23
ID Boise 5.83 3.33 4.92 SC Charleston 5.72 4.23 5.06
ID Twin Falls 5.42 3.42 4.70 SD Rapid City 5.91 4.56 5.23
IL Chicago 4.08 1.47 3.14 TN Nashville 5.20 3.14 4.45
IN Indianapolis 5.02 2.55 4.21 TN Oak Ridge 5.06 3.22 4.37
KS Manhattan 5.08 3.62 4.57 TX San Antonio 5.88 4.65 5.30
KS Dodge City 4.14 5.28 5.79 TX Brownsville 5.49 4.42 4.92
KY Lexington 5.97 3.60 4.94 TX El Paso 7.42 5.87 6.72
LA Lake Charles 5.73 4.29 4.93 TX Midland 6.33 5.23 5.83
LA New Orleans 5.71 3.63 4.92 TX Fort Worth 6.00 4.80 5.43
LA Shreveport 4.99 3.87 4.63 UT Salt Lake City 6.09 3.78 5.26
MA E. Wareham 4.48 3.06 3.99 UT Flaming Gorge 6.63 5.48 5.83
MA Boston 4.27 2.99 3.84 VA Richmond 4.50 3.37 4.13
MA Blue Hill 4.38 3.33 4.05 WA Seattle 4.83 1.60 3.57
MA Natick 4.62 3.09 4.10 WA Richland 6.13 2.01 4.44
MA Lynn 4.60 2.33 3.79 WA Pullman 6.07 2.90 4.73
MD Silver Hill 4.71 3.84 4.47 WA Spokane 5.53 1.16 4.48
ME Caribou 5.62 2.57 4.19 WA Prosser 6.21 3.06 5.03
ME Portland 5.23 3.56 4.51 WI Madison 4.85 3.28 4.29
MI Sault Ste. Marie 4.83 2.33 4.20 WV Charleston 4.12 2.47 3.65
MI E. Lansing 4.71 2.70 4.00 WY Lander 6.81 5.50 6.06
MN St. Cloud 5.43 3.53 4.53

Several useful energy calculators for cross-checking the numbers can be found at this site:

http://www.alternate-energy.net/calculateamp02.html

A definition – Peak Sun Hours: The equivalent number of hours per day when solar irradiance averages 1 kW/m2. For example, six peak sun hours means that the energy received during total daylight hours equals the energy that would have been received had the irradiance for six hours been 1 kW/m2.

http://homesolarwind.com/47/solar-efficiency-peak-sun-hours-rated-power-solar-panels.html

Solar Efficiency – Peak Sun Hours and Rated Power of Solar Panels
When calculating the solar efficiency of your installation a figure known as “peak sun hours” is used to estimate the power output of your solar panels. If you have looked up the number of peak sun hours for your area you may be wondering why that number appears to be so low. So what does it really mean?
The amount of radiant solar energy falling on a surface is commonly measured in Watts per square meter (W/m2). This quantity will vary according to your location as well as the season, time of day and weather conditions. The radiant energy from the sun at its peak (around noon on a clear day) falling on an adjacent surface is about 1000W/m2. It obviously won’t be so powerful when it’s lower in the sky, and in fact will be changing all the time throughout the day, so how can we simplify things to make it easier to calculate our solar efficiency?
If someone were to measure this radiant energy and take the average over the whole day we might ask them “How long would it take to gather the same amount of energy if the sun was always at its peak, delivering exactly 1000W/m2?” The answer to this question would be the peak sun hours for that day. It’s the number of hours it would take to gather the same amount of energy if the sun were always at its peak.
So why is it so useful to work in peak sun hours? The short answer is “Because it’s a standard”. When you look up the solar irradiance (or insolation) for your location, chances are it will be expressed as peak sun hours, and may be averaged across the months, seasons or even the whole year. It’s common practice to quote one figure for summer and another for winter so you can work out the worst-case performance when calculating your solar efficiency.
The solar panels you buy (or cells if you are making your own panels) will have their power rating specified at what is called “standard test conditions” or STC, which define a fixed air pressure, temperature and irradiance when measuring the panel. And what is the standard irradiance? You guessed it – 1000W/m2.
Here’s a quick example so show how this all fits together. Let’s say your location gets on average 3.5 peak sun hours a day. You have a 100W panel and want to know how much energy you can expect from it. You simply multiply these two figures together: 100W x 3.5 peak hours = 350Whr of energy per day, on average. In reality this will most likely be slightly lower due to panel tolerances and temperature. Peak sun hours are a standard quantity that can simplify the task of sizing solar panels and calculating your solar efficiency, and make the calculations much easier.


A special thanks to The Power Company for taking the time to answer our questions about solar, I’m sure they get these same stinkin’ questions every day!  If you do call them make sure you think of a clever question to ask that will throw them off…then give them the secret code “the Wynn’s are awesome” and they’ll understand.  Ha.  Hope this helps clear up your questions about solar, or at least maybe you can relate to one of the packages:  BASIC, MEDIUM, or HEAVY.  Hopefully this will help you decide what solar power package might be best for your needs and budget.

Do you have personal experience with RV solar systems?  Please tell us what you think in the comments below.  Make sure you let us know how many panels and the wattage so we can do the math!

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