Backwoods Summer 2016 Road Trip Report I

OSEIA 2016

By Erika Karnitz VP of Wholesale

I attended the 2016 Oregon Solar Energy Conference (OSEC) on May 4th and 5th in Portland Oregon. The conference drew 380 attendees this year, as opposed to last year’s 251. Each day was chock full of training’s, policy round tables, and networking opportunities.

Tuesday May 3rd kicked off the event with a “solar soiree” in the evening featuring drinks, snacks and a chance to say hi to everyone before we got down to business. Jeff Bissonnette, Executive Director of OSEIA gave an opening speech about the bright future of solar in Oregon.

Wednesday morning started with a keynote address by Rhone Resch, President and CEO of the national Solar Energy Industries Association (SEIA). He took a poll of the room and it was interesting to see that many of us had Customer Owned Utility round tablebeen there 5, 10, 15, and even 20+ years. He talked about Oregon Senate Bill 1547, which set as 50% renewable portfolio standard (RPS) by 2040 and requires the elimination of coal-generated electricity in the state power mix.  The bill also creates a community solar program, allowing Oregonians without solar suitable roofs to own a portion of a larger central array and have credits applied to their electricity bills. SEIA expects Oregon have one of the fastest growing solar industries in the country in the coming years.

Wednesday I attended some interesting training’s. The first was a product and technical training by Solarworld. They talked about their new line of high efficiency monocrystalline modules, which are 60 cell and 300W. They are using a 5 busbar technology, which in conjunction with high quality mono cells is enabling them to reach 300W in the same footprint as they have used in the past. Per Solarworld ” By moving from three to five bus bars, the primary electrical contacts that stripe photovoltaic cells, SolarWorld can manufacture cells and modules in which electrons travel shorter distances from grid lines to bus bars and thus enable more to reach the bus bars. The advance lifts module power by 2 percentOB training Sandraage points. “

Another interesting new product being offered by Solarworld is the “Bisun” module, which is a bifacial solar module. Bifacials have been offered in the past by companies such as Canadian Solar and Sanyo, but the Solarworld will be the only one currently in production to my knowledge. The amount of additional power generated by bifacials depends greatly on the reflectivity of the surface that they are installed on and the method of install. An ideal install would be elevated and on a white membrane roof. Solarworld claims up to a 25% increase in power generation compared to a standard module of the same wattage. They are currently testing outputs at an install in VA.

The next training I attended was “Inverter Best Practices”, taught by Jeff Laughy from Solar Edge. It was a good overview of different inverter types, with a focus on SolarEdge inverters and optimizers. He discussed the significant impact recovery from shading that is possible by using MLPE (module level power electronics). Rhone ReschMLPEs include microinverters and power optimizers. Tests have indicated that if you are in an area that receives shading, you can recover 25% of the lost power by using MLPEs. According to SolarEdge, 60% of residential installs are currently using MLPE technology.

Jeff also spoke about SolarEdge’s partnership with Tesla in making a storage solution for grid tied systems. The StorEdge 7.6kW inverter and appropriate optimizers can be used with the Tesla Powerwall to create a grid tied solar system with a 6.4kW storage capacity.

The last session I attended on Wednesday was “Preparing for Disaster Resiliency”. Rick Williams, Director of the Columbia Region Leidos Maritime Solutions, has been working with Portland State University and others to come up with solutions to make the PV installs in the area more ready in the case of a large grid outage. They have been discussing establishing community centers that would allow residents to shelter in place.

Thursday I attended the “Grid Tied Battery Backup Systems” class, taught by Sandra Herrera and Brian Lawrence from Outback. We learned a lot about Radian system design and implementation. We also talked about the other products in Outback’s lineup that are suitable for grid tie with battery backup.

The 2016 OSEC was a whirlwind of learning, networking, and fun. There were several after-hours opportunities to mingle with other solar professionals, and it is always a pleasure to see the faces of my northwest solar friends. OSEC remains one of my favorite conferences because of its smaller size and ample training opportunities. See you there next year!


Solar Panels Powered Water Pumping

Solar panels that power water pumping systems are an excellent solution to the water and water storage issues on our minds. As availability to solar energy becomes more affordable and much more efficient, the choice to change to a DC solar-powered water pumping in remote applications becomes clear.

There are many remote situations where a solar-powered water pump just makes more sense compared with a conventional grid-connected AC pump. Using solar panels to pump water can greatly relieve the work load and expense for many rural people.

AC vs. DC Pumps

Depending on the application-irrigation, ponds, livestock, deep well water storage, or for an off grid water source-consider changing your existing AC pump and/or installing a new DC solar-powered pumping system closer to the water source.

The age old argument is that AC pumps are faster and can last longer. However, they use 4-8 times the amount of power per gallon than slower DC pumps. AC pumps can also be maintenance intensive and unpredictable at times, causing additional strain on inverters in off-grid systems when other loads are running.

Most DC solar-powered pumps use half the energy consumed by an AC jet pump and can be more cost effective due to location and/or fuel dependence. A solar solution is cleaner and now cheaper than it has ever been.

Things to Consider With A Solar-Powered Water Pump

There are some basics you will need to know before you make the move to a solar direct water pump. We have also included a diagram near the end of the article that defines some of these terms further.

  • How deep is your well or other water source? “Water source,” can refer to any well, spring, creek, or storage tank. Depth is a crucial measurement and is usually measured in feet and is incredibly helpful when communicating with manufacturers or distributors. The depth of your well or water source determines the type of pump you will need. When pumping from a storage tank, cistern, spring, or creek you may need a shallow level submersible pump or surface pump.
  • What is the Static Water Level or Static Head in the well? This is the measurement from ground level of the well to the top the surface of the water rises within the well on its own with the natural production of the underground spring or stream.
  • If you have an existing well, do you know how many gallons per minute your well produces? Usually your well driller can provide you with this information, you might have it already, or you will have to estimate how much “draw-down” the well will have during pumping.
  • How many gallons per day will you need?
  • Are you planning on pumping to a non-pressurized holding tank or to a pressure tank?
  • How many feet above the well head is the tank located?
  • If you will be using a pressure tank is how many pounds of pressure will you need from the pumps performance?
  • If PV direct, without batteries, how many feet from the array to the well head (either of the surface pump or a submersible pump deep in the well? Some of the finer details that are often overlooked in the planning stage are the distances that the wire or conduit from the PV modules will need to be to get to the well head. If there is a battery bank, the distance from the well head to the battery system will have to be measured.

Utilizing a Storage Tank

Adding a storage tank and increasing the size of the pumping system means that you can have excess water stored for continual use during the night or when it’s cloudy and the pump is off.

The purpose of a storage tank or drinking trough is to allow a very consistent trickle flow of water constantly pumping throughout the day building up a large volume of water to supply brief periods of high water use. DC powered submersible deep well pumps may be the best choice because they do not require large bursts of power or use the inverter at all.

As touched on previously, DC submersible pumps only use 20% to 50% as much energy per gallon pumped as an AC centrifugal pump. Most of these pump very slowly and have less of a chance of depleting the water level in a slow recovery well.

They can be powered direct by solar modules, without batteries, or they can be powered by the same battery bank in an off-grid power home like any DC appliance as long as the well is within about 200 feet from the house. These submersible pumps will not freeze or lose their prime.

Designing a Solar-Powered Water Pump

Technical drawing of an example solar powered water pumping
An example diagram of a solar powered water pumping and storage solution.

So, this leads to the next couple of questions to consider as you design your system.

Do you want to power the pump directly from a PV array, which implies that you will only get water when the sun is shining unless you have a storage tank?

Or are you considering that you would need to have your pump powered by a battery bank for additional pumping in times of little to no sun and into the evening? Batteries are also sometimes desirable to provide sufficient surge power for starting the pump.

At this point, drawing a rough diagram of your proposed system is a good idea so that you can indicate which measurements you will need and identify sources, storage, final discharge points, and required components to go solar. A solar-powered water system is one of the easiest solar power systems to install and will ultimately save you time and money.

As with any system, Backwoods Solar is here to answer any questions and help design the perfect solar panels off-grid power system to meet your needs. Contact Us for help with your off-grid power project today.

Bogart Engineering’s Solar Battery Charge Controller

The  solar battery charge controller, SC2030, is manufactured in the U.S.A. and presents unique advantages for solar.

The SC-2030 higher voltage finish charging is intended to compensate for this by boosting voltage towards the end of charge when the current declines. It is then important not to go too far or too long at this higher voltage (107% overcharge” does not mean 107% of the total battery capacity. It means 107% compared to the previous low discharge point during the last discharge cycle).

If the previous discharge was very shallow, it may be only a small number of amp hours extra, compared to what was removed last time. This is why measuring the percent overcharge is important to keep from overcharging; a function that is monitored by connecting with the TriMetric-2030. Also regulating the charge current when the voltage is high is important. The SC2030 doesn’t allow the voltage to go above 14.3V until the current drops to 2%of C.

The SC-2030 is a precision, high efficiency PWM (pulse width modulated) Solar Array Battery Charge Controller. The objective of this design is to maximize the life of your solar panels batteries by allowing the flexibility to adjust solar charging specifically according to the way your battery manufacturer has specified. The success of its high performance depends on being connected to a TM-2030 (TriMetric Battery System Monitor). This controller is only recommended for use with 12V or 24V solar panels.

Many people believe that MPPT type chargers are always better than PWM chargers, however when Bogart compared theirs to at least one commonly used MPPT charger they found that under very ordinary conditions the SC-2030 delivered more charge to the batteries. The conditions in which the SC-2030 was measured and tested were: at an ambient temperature of 70 F degrees in full sun, and when the proper panels were matched to the batteries and charging was over 13.0 volts (the most common charging range with lead acid batteries).

The SC-2030 Solar Charger, working with the TM-2030 battery monitor has never before seen benefits that can extend the life of your battery system. Made in the U.S.A. and available soon!

 For more information please visit:

Sales brochure is available here (page 2 lists the SC2030):

For more detailed information:

Here is additional information from battery companies on how you to decide when to go to float:

For Trojan, pay special attention to the graph on page 19. Caution: be sure to go into float when a specific amount percentage of overcharge is achieved– about 115% of overcharge (compared to last discharge). This is important to avoid overcharge.

For Rolls AGM batteries, pay special attention to the graph on page 25. This chart, unlike Trojan, has the important information that tells when to go into float:  They call this “IUI” charging. Note this on graph: Termination: F= 2.5mV/Cell/hr or 105-110% recharge.

For US Battery’s liquid electrolyte batteries, view page 2 and 3. “Constant current, constant voltage, constant current” charging instructions.  Charging at 20% C is OK up to 14.4V– but above  14.4 volts they suggest charging up to 15.3 volts provided  the charge current is limited to  3%C (at temperature of 77F) This is what they consider to be the optimum method–what they call the “three stage” charging method. This mentions a dV/dT criterion as well–but this is impractical for solar because it requires the current to be absolutely steady current, which solar isn’t; measure percent of overcharge instead. Also see the second paragraph on page 1 that mentions the overcharge percentage–but shows an unusually wide range.

For Full River, see what they call IUIU charging characteristic for their AGM batteries.

For Concorde, they recommended 107% overcharge, with voltage going as high as 17 volts. It’s important to limit current to 2%C when going up to 17V. When charging current is higher, the voltage must be limited to 14.3V. See page 20

For Interstate, same as Concorde

Getting Your Off-Grid System Ready for Winter

Written by Backwoods Technician Alan Smith

Preparing for winter is best practice for extending the life of your off-grid power system, especially for those of you in cold and snowy climates.

Now is a good time to review the maintenance and condition of your power system (even for those of you in warm and dry climates).

It’s better to check on your system at your convenience rather than when something goes wrong in the middle of the night in three feet of snow or a flash flood. Here are the things you should check on and look into if something seems out of place.

Seasonal Angle: For Greater Energy Harvest & Shedding of Snow

If you have an adjustable rack mount for your panels, it is worth tilting them to the ideal angle to properly capture the winter sun.

An appropriate angle can make a big difference in the amount of power collected, especially during the shorter, cloudier days of the winter when sunshine is at a premium.

The ideal angle for your panels is easy to determine. Use the latitude of your location and add 15 degrees. The result is the angle of tilt of the panels, measured up from horizontal that will yield the best harvest during the winter months.

Example:  Sandpoint, Idaho is at 48 degrees north. Ideal winter angle is 48 + 15 = 63 degrees. 

For the folks that have vacation cabins that may only be visited once a month or so during the winter, consider a steeper angle to accommodate easier shedding of snow.

Clear Off the Snow

Remembering to clear off the snow seems obvious, right? Keep a broom or brush on a telescoping handle if needed and clear any freshly fallen snow off the panels on a routine basis.

If you let the snow sit and freeze on the panels, it will take that much longer until your panels are able to collect solar rays again.

It’s a horrible feeling to be sitting at work, when the grey skies open up to sunshine, and you know your array is sitting at home with six inches of snow on it. Make it a regular habit to brush them off whenever it snows.

Generator Tune-up

Now is the time to do your annual generator maintenance.  Besides the basics-oil, belts, coolant level, air filter, and spark plugs-be sure to check your owner’s manual for items specific to your machine. Check on the starter battery. If the generator has not been run since the previous winter, it is very likely that the starter battery may be dead or heavily discharged. Replace or recharge it before you need it.

Off-Grid Batteries

Batteries can be kept in a relatively cold area, with a couple of considerations. First, the energy storage capacity of batteries in a cold climate is temporarily reduced. Instrumentation such as battery monitors can be fine-tuned to reflect a more accurate state of charge.

Temperature sensors for both your charge controller and inverter/charger should also be used for optimum charging points of your batteries. Fully charged batteries, being used on a daily basis, will not freeze until the temperature drops to -70 degrees F. A battery at 50% state of charge, though, can freeze in temperatures as “warm” as -10 degrees F.

Don’t let the batteries get too low. The sulfuric acid in batteries that are being stored or lightly used will tend to stratify. This means that the water begins to separate out from the solution, resulting in layers more like water near the top of the battery and denser layers of sulfuric acid towards the bottom. If this occurs, it is very possible for the water layer to freeze at temperatures near 32 degrees F and crack the battery casing.

Extended Leave

When the power system will be unattended for extended periods of time, we have to make the best of a non-ideal situation.

Flooded lead acid batteries respond best to daily use, so depending on your installation and equipment there is a couple of options available.

Opinions on the best approach will vary. If you have an automatic generator start (AGS) function tied to your inverter/charger and you consider your generator to be highly reliable, the inverter can be left on so that a charging source is available if the panels become covered in snow.

If you do not have AGS, turn the inverter off. Turn all DC loads off. Leave the charge controller on, with the goal of supplying at least a bit of float charge to the batteries each week.

If available, ask a neighbor to check your array after any major snow storm to brush the snow off. One school of thought suggests reducing voltage settings, to reduce water consumption, and setting the equalization to automatically occur once per month.

Tuning Gear, More Panels, & Winter Behavior

The sun tends to be shy in the winter. Let’s take advantage of the days it does show up. An experienced system owner will know how their system responds to normal charging and equalizing. Consider increasing the absorb time and the equalize settings on your charge controller for the winter months.

Keep a notebook handy in your power room and write-down the summer and winter settings that you find work best, so you know what to change them back to when the seasons change. Search mode on an inverter should be enabled year-round, but especially so during the winter. A couple hundred watt-hours per day can make a big difference.

How Many Solar Panels Should I Get?

You honestly can never have too many solar panels, we can all agree on that. How much is too much though?

It depends on your geographical seasonal factors and budgets. The idea being that, if you can manage to get one good sunny day a week during the winter, you’ll really harvest some good power and minimize your generator run-time and fuel use. Long time off-gridders will tell you they simply change their behavior during the winter months.

For example, leaving the coffee pot on for an hour is fine in the bountiful sunny days of summer, but the coffee maker gets turned off after 15 minutes in the winter, and the coffee goes into a thermos. Or better yet, wait until you get into work and make the coffee there! Less TV time and more book reading cuts down on the power used too.

Simple conservation in several small steps (replace light bulbs with LED’s) can add up to a big difference in the amount of power needed during the winter. It’s better to take care of your system now, than to experience failures at the most miserable time imaginable.

Routine maintenance and a thorough knowledge of how your system responds to your daily usage will serve you well, not only for the winter, but for the lifespan of your system as well.

Stay warm and don’t forget to keep your snow chains, a shovel, and a bag of sand in the trunk of your car! If you’re interested in fine-tuning your off-grid power system or setting one up for winter, Contact Us at Backwoods Solar at 208-263-4290 for help designing a customized renewable energy system that works best for you.

Back of the Module Technology in Grid-Tied Systems

Grid-tied systems either incorporate a small inverter at the module, or a series of DC power optimizers running to a central inverter. They are best used in arrays that have shading issues or varying module specifications (mixed modules). Module level MPPT and system performance is monitored and additional gains over the life of the system are realized.

Module Technology in Grid Tie Systems - Solar Panels for Home - Backwoods Solar

Micro-Inverters for Solar Panels

Most grid-connected solar energy installations use a single centralized inverter to convert the DC output from multiple solar modules that are wired in series strings into AC power. Some disadvantages to systems of this type are scalability, limitations in string sizes, shading concerns that reduce the power output over an entire string of 10 – 14 modules and high-voltage DC wiring.

Micro-inverters mount easily behind a solar panel and convert the DC output of the solar module into grid-compliant AC power at the module. This simplifies the installation, increases efficiency, avoids high voltage DC wiring and the requirements for DC switchgear. Micro-inverters also allow the homeowner to add to their system as budget allows, starting small and growing the size of the system over time with near plug and play ease.

Depending on the inverter you choose, there are several installation options available. Depending on the wattage of your module, you will want to choose the inverter that maximizes the performance output to avoid clipping. You want to make sure that the inverter is rated above your modules true output after de-rating for temperature and efficiency losses.

With micro-inverter systems, each modules maximum power point is achieved within the array, meaning that as the sun crosses over the array, or as clouds pass across the sky, the modules performance will increase and decrease; however the entire strings performance is not jeopardized. This can equate to significant gains in overall system performance over time.

Many micro-inverter systems collect information for each solar module in a user’s system and transmit data to a computer interface, where users can view their solar power system performance. Most transmit data over the existing power line, so no additional wiring is required. A graphical representation of the solar array provides information on the status of each module.

A significant benefit to module level monitoring is being able to quickly pin-point under-performing modules for warranty issues and soiling concerns.

DC Power Optimizers for Off-Grid Power

Another back of the module technology incorporates a DC power optimizer box at each module, these boxes are then wired to each other in long strings and then finally to a string inverter at the home. Similar to micro-inverters, they offer advantages of module level power point tracking and eliminate concerns of performance loss due to shading and soiling of a single module within a string. Efficiency gains over the life of the system are also realized.

The major difference between the two is that the conversion from DC to AC is not happening on the roof. DC power is still carried to the integrated string combiner at the inverter, and the final inversion/conversion to AC power is done at the house, similar to a traditional string inverter.

These systems are also scalable, typically starting as low as 8 modules, and allow for the homeowner to add a single module at a time up to the allowable string and inverter limitations. Module level monitoring is provided without the need for any additional hardware and typically without any additional charges. Both of these types of systems are much easier and safer for someone to install and eliminate a lot of the sizing equations needed in traditional string inverter systems.

If you’re interested in learning more about how or which module technology would work best for your solar panels for your home, Contact Us at Backwoods Solar today. We only sell products that we’ve tested as tried and true.