Oasis Montana Inc.
Renewable Energy Supply and Design
406-777-4321or 4309
e-mail: info@oasismontana.com
Home Page: www.oasismontana.com

Visit us on the web for product and project information!
For grid-tied power systems, www.grid-tie.com
Solar water pumping:  www.PVsolarpumps.com
Non-electric gas appliances, www.LPappliances.com
Efficient and DC appliances, www.eco-fridge.com
And our main page at www.oasismontana.com

Solar grid-tie inverter roundup
Oasis Fall 2005 Newsletter

For those of you who aren’t familiar with solar grid-tie inverters, a brief overview of how they work is in order. These inverters allow you to easily connect a solar array directly (i.e. without a battery bank) to your home’s AC breaker box. From there the DC power generated by the solar modules is inverted to AC and it is either used directly by your AC appliances or it is sold back to your utility company which lowers your monthly electric bill. This is the most efficient and least costly way to “go solar” since there is no expensive battery bank to purchase and maintain. The one drawback of this type of system is that it cannot provide backup power during a utility outage since the inverters shut down for safety reasons. 

If you are interested in this type of solar power system, the first thing you should do is contact your utility company to see if they will allow you to connect such a system to their electric grid (as not all utility companies will). The next thing to ask them is if they offer “net metering”, where they pay you the same rate per kilowatt-hour of energy that you pay them. Without net metering, a solar grid-tie system is not very cost-effective. The last thing to ask your utility company is how long they will allow you to carry over any excess energy production (hopefully for a full year). If you get all of the right answers from your utility company, the next step is to determine how much energy you would like the grid-tie solar system to produce. The limiting factors in determining the maximum size of your solar system are either available roof area or budget (also, you can install these on the ground on differing mount structures). After the solar array size is determined, the next step is to figure out which inverter(s) will work best for your chosen solar array. This can be a little tricky due to many factors (number of solar modules, solar module voltage vs. inverter voltage, physical module layout, minimum winter temperature, etc.) so give us a call and we will design the whole system for you. If your solar array size is too large for one inverter to handle, that isn’t a problem because these inverters are modular—so you can install multiple systems on your home if your budget allows, or do it incrementally. A grid-tie solar system is very easy to wire and install since most of the inverters use 1 to 3 high-voltage series strings of solar modules (hence their nickname “string inverters”) along with simple disconnect switches on the DC and AC sides. Some of the grid-tie inverters incorporate these required disconnect switches into their design and all of them have the NEC required DC ground fault detection/interruption protection for roof mounted solar arrays. 

Rather than writing a long and probably boring article (or have we just done that?) about the features of each inverter, we put together the chart below comparing units from SMA, Xantrex, Fronius, Sharp and PV Powered, which we think are the most popular brands for residential and small commercial solar applications. Each unit’s peak power rating is part of the model name so we didn’t list it separately. Hopefully this chart will help you choose the grid-tie inverter that has the features you want and will best meet your needs. Of course if you have any questions about these grid-tie inverters or if you would like us to design a grid-tie solar system for you, please contact us via phone, fax or e-mail. 


Manufacturer & model Input  VDC Peak Efficiency AC & DC Disconnects Digital Display Weight  Warranty
SMA SB1800U 156-400 93.6% No Optional 59.4 lbs 5 years
SMA SB2500U 50-600 94.1% No Optional  71 lbs 5 years
SMA SB3800U 200-500 95.6% No Standard 85 lbs 5 years
SMA SB6000U 234-600 >95% No Standard 137 lbs 5 years
Xantrex GT 3.0 195-600 94.6% Yes Standard 45 lbs 5 years ***
Fronius IG 4000 50-450 94.4% Yes Standard 42 lbs 5 years ***
Fronius IG 5100 150-450 94.4% Yes  Standard 42 lbs 5 years ***
PV Powered 2800 200-450 97.6% No Standard 74 lbs 10 years
Sharp JH-3500 110-380 92.4% No Standard**  62 lbs 5 years
*All of the units above have a 240 VAC 60 Hz output with the exception of the SMA SB1800U which has a 120 VAC 60 Hz output. All of the 240 VAC units listed are available for 208V 3-phase applications.

**Sharp’s digital display is designed to be mounted remotely. 

***Optional 10 year warranty available.

For manufacturer's information about these inverters, you can check out these links:





   It took 125 years to consume the first trillion barrels of oil; we will likely
 consume the next trillion barrels within just thirty-five years. 

Oasis Montana Fall 2005 newsletter navigation

Contents Page 1 Page 2 Page 3 Page 4
Now in autumn, we are enjoying cool and wet (even snowy) conditions, but it was one hot and smoky summer and fall for many parts of the western U.S., and Montana was no exception. We were smug with our good snowpack, back in spring. Then our summer started with a week of 100+ degree weather, and continued to stay hot. We were blanketed in smoke from the horrific fires (1.3 million acres burned) until the middle of September, and unfortunately, many homes and a few lives have been lost. We have been able to help some people with water pumping to protect their properties, but our drought conditions and warm temps made for a very dry western tinderbox. If only those folks in Texas could’ve share perhaps 1/20th of their deluge from their state…

Even so, the garden and fruit trees kept us busy, and despite the smoke we still enjoyed camping, fishing, and canoeing in our local river (even though the water was quite low). We hope our legislators will work on commonsense future measures to mitigate the effects of warming temperatures and prolonged drought. One thought we have had (since we were less than a mile from our local small airport, a helibase that launched many helicopters and other aircraft for fighting fires) is that actual planning for these events would be a good idea (seeing as they are now part of our new normal)—how about reservoirs near these airports to make hauling the big buckets faster and more affordable? Here in Stevensville, we have several large irrigation ditches in close proximity to our airfield…. Well, it’s just my 2 cents worth!



PICOCELL controller inverter for array-direct water pumping

 for your 240VAC pump.
In this issue we have some new products to share; one is an exciting new AC soft start pump controller/inverter that can run your 240VAC (or 120V, or 3 phase, or 230VAC 50 hz) 1/3 to 2 horsepower pump directly off of a solar array – click here for more information on the PICOCELL controller/inverter (cost: $1220 plus shipping). This exciting new technology is designed for off-grid use, or emergency back-up. We have installation manuals, spec sheets, and pump kit information on our water pumping site.  Call or e-mail for more information.



New, small Energy Efficient AC refrigerator

We also have a new, small AC refrigerator, 7.1 cu.ft. for your home or cabin, the CP972SS. It’s a great size for space-limited kitchens, only 22”W x 22”D x 57”H and will sell at the great price of $459 plus shipping. With its lean size, the CP972SS is the ideal refrigerator for studio apartments, yachts, offices, and other settings in need of reliable cooling in a slim-fitting footprint. Visit here for more information on this and other (larger) refrigerators.



Just a reminder, we offer a line of non-electric propane refrigerators, freezers, cooktops and ranges at www.LPappliances.com, and a line of efficient AC or DC refrigerators and freezers at www.eco-fridge.com.


The best nuclear generating station is 93 million miles away, and is available for pretty much everyone!
Thomas Edison quote on Solar Energy

Iron Edison Batteries
We also have a new line of batteries to offer, manufactured by Iron Edison;

Iron Edison BatteriesOver a century ago, Thomas Edison found a battery design that he considered to be nearly perfect. Today, Iron Edison is proud to offer an updated version of this incredible design that is specifically manufactured for renewable energy systems. Iron Edison carries a variety of nickel iron batteries: 12 volt, 24 volt, and 48 volt configurations, each configuration with amp-hour capacities of 100 Ah through 1000 Ah.

visit our information on this exciting new product line.


The International Trade Commission (ITC) is responding to a lawsuit brought about by SolarWorld and Suniva (U.S. module manufacturers) that low cost imported (i.e. Chinese) solar modules have hurt their competitiveness, so they are asking for a tariff on imported solar panels to ‘level the playing field’. Many pro-solar groups are opposing these tariffs, as they will increase the dollar-per-watt cost of installed solar power systems, and very negatively impact job growth in the solar sector – which had been bourgeoning in the past few years. In fact, it is estimated that 1 out of 50 new jobs is in the renewable energy sector. The ITC has approved tariffs, but it will be up the President Trump to set the rate; those of us in the industry are waiting to see what will happen, and many jobs are on hold pending the decision. It sounds like costs may go up 10% to as much as 40%. For more information visit:  https://pv-magazine-usa.com/2017/10/31/breaking-usitc-recommends-quotas-tariffs-on-crystalline-silicon-solar-imports/  and https://pv-magazine-usa.com/2017/11/13/the-clock-ticks-itc-turns-section-201-over-to-president-trump/

Renewable Energy (and related) news bites

             1912 Warning on coal cuasing climate change


  • When autumn darkness falls, what we will remember are the small acts of kindness: a cake, a hug, an invitation to talk, and every single rose. These are all expressions of a nation coming together and caring about its people.
    --Jens Stoltenberg
  • Designers want me to dress like Spring, in billowing things. I don't feel like Spring. I feel like a warm red Autumn.
    --Marilyn Monroe
  • The cost of solar energy has not been opened up because the oil industry does not own the sun.
    –Ralph Nader
  • The spring, summer, is quite a hectic time for people in their lives, but then it comes to autumn, and to winter, and you can't but help think back to the year that was, and then hopefully looking forward to the year that is approaching.
  • A kestrel can and does hover in the dead calm of summer days, when there is not the faintest breath of wind. He will, and does, hover in the still, soft atmosphere of early autumn, when the gossamer falls in showers, coming straight down as if it were raining silk.
    --Richard Jefferies
  • I love nuclear energy! It's just that I prefer fusion to fission. And it just so happens that there's an enormous fusion reactor safely banked a few million miles from us. It delivers more than we could ever use in just about 8 minutes. And it's wireless!
  • I prefer winter and fall, when you feel the bone structure of the landscape - the loneliness of it, the dead feeling of winter. Something waits beneath it, the whole story doesn't show.
    -- Andrew Wyeth
  • There has been a systematic repression of solar energy. It seems pretty funny to me that the government, if it is completely neutral--why wouldn't they pursue this far safer alternative of solar energy with the same intent that they pursue nuclear energy? Solar power is the last energy resource that isn't owned yet--nobody taxes the sun yet.
    --Bonnie Raitt
  • The problem with winter sports is that--follow me closely here--they generally take place in winter.
    --Dave Barry
  • If we had no winter, the spring would not be so pleasant: if we did not sometimes taste of adversity, prosperity would not be so welcome.
    --Anne Bradstreet

Please feel free to share this newsletter – knowledge is power!

Visit us on the web for product and project information!
For grid-tied power systems, www.grid-tie.com
Solar water pumping:  www.PVsolarpumps.com
Non-electric gas appliances, www.LPappliances.com
Efficient and DC appliances, www.eco-fridge.com
And our main page at www.oasismontana.com