Backup Generator for 8Kw and 1000Ah Off-Grid System

Anawa · June 2017

I was planing on using the Kohler 8.5 RES backup generator, but they are now discontinued. Anybody got any suggestions?

Looking to install Outback Radian with Xantrex Controllers.

Vic · June 2017

Hello Paul,

First, regarding your question;
Is there a replacement from Kohler for the 8.5?

Then there is the question about Warranty coverage on these gensets. Just did look at the Spec Sheet on the 8.5, and it has the customary Kohler requirement that that genset was for Standby on Grid-Tied homes, or similar wording, BUT does note an 18 Month Warranty for off-grid applications:
https://www.firemountainsolar.com/product-archive/kohler-8-5-res-residential-backup-generator/

Off-Grid applications often have extended run-time frequency, and duration. This can be rough duty on these gensets, which are often air-cooled.

The second comment has to do with running Xantrex CCs with the OB Radian inverters.

Unless you need a CC with a 600 V maximum String Voltage, I wonder about the Xantrex CCs, as they need one or two added widgets to monitor and perhaps to install FW Updates the CCs.

Have you considered the MidNite Classic CCs?

Some will say that there is an advantage in using all the solar power components from a single manufacturer for better monitoring/control, etc, ... but I have never been a believer in that, personally.

The OB FM CCs are a fairly old design at this point, and seem to have limited functionality.

Just FWIW, Vic

Vic · June 2017

Link to a third-party's Monitoring/Programming software that runs under Windoze:

http://www.n1gnn.com/ClassicStatus4Plus/Info.html

FWIW, have not used it ... Vic

Anawa · June 2017

Thanks again Vic for your useful comments.

I haven't found anything yet that Kohler offers as a comparable replacement for that particular genset, thus I threw it up on the forum for some help. I'm open to alternatives, including Honda EU's, etc. I will need the auto start and propane capabilities.

Regarding the Xantrex CC's, I will have about 250 feet from the combiner box at the array to the CC's and NAWS is recommending the 600v unit: 2 strings of 15 Kyocera 265v panels. I'm still in the "deciding" stage on the CC''s and open to discussion in selecting between the Midnite's and the Xantrex. I'm curious how well each type will interact with the Outback.

I have all Outback equipment on my main system and I have become quite familiar with it. It has served me well, so far. I frequently use the Mate3 remote monitoring capabilities (OpticsRE) and intend to add this new system to my account so my nephew can monitor this new system, since it will be his.

FWIW, I've found that the primary focus of my remote monitoring is on the battery: remote manual start-up and changing start-up parameters I have done from time to time. I do not think I would ever need to re-set controller charge settings, so mixing other CC's with the Outback equipment may not be an issue, but I don't know for sure.

Vic · June 2017

Hi Paul,

Thanks for the added detail.

While I am not a real fan of the Schneider Solar Power equipment, but agree that the 600 V 80 A CC looks attractive in situations like you are facing. Looks like you might need two of those, using standard rules-of-thumb. And guess that the Schneider Combox might suffice for Programming/Monitoring/FW Updates, IIRC.

Think that NAWS is a top-notch supplier, so they are a good source of info/advice and product.
BTW the KD-265s sure seem like a real deal right now ...

Did finally find the standard Kohler Five year 2000 Hr Warranty for "Stationary Standby" applications:
https://www.electricgeneratorsdirect.com/manuals/Resi Warranty 5yr 8 5142030RES TP6479.pdf

It has their customary requirement that it is only for Standby uses -- sites served by Commercial Utility power. Guess that you wanted the 8.5 RES because it DID have a Warranty provision for off-grid use ...
Although, the installation that you are planning might really have some form of Grid Interactivity, given the system size, and therefore might comply with Kohler Warranty provisions.

That Kohler 8.5 might have been a bit small for the size system that you are designing.
Have used a Honda EU 6500 is, but the way it interacts with the old Xantrex SW+ Inverters here, is less than ideal -- the 6500 gets pulled out of AC voltage regulation, when the inverters are in a voltage-regulating charge stage (like Absorb, or EQ), and there is also significant PV power production. This is probably only an issue with these old SW and SW+ inverters. A larger traditional genset does not have this problem on the systems here ... just FWIW.

Have a 18 kVA Kohler LP genset which has been fine. It is powered by a 2.4 L Ford inline four engine at 1800 RPM, and as one would expect, it is a fuel HOG.

OK, good luck with the new system design. This is always fun. Vic

Anawa · June 2017

Vic, couple of things. I'm more than a mile from any grid connection and pretty much "out in the woods". And yes, I figured 18 months warranty for Kohler 8.5 RES for off-grid use was worth more than.... nothing.

I suppose as a result of the Outback FNDC, the genset auto-start functions (load, voltage, SOC) are programmed via the Mate3 and does not involve the CC's. So, maybe the headaches you describe above with the Xantrex CC's are not an issue? What do ya think?

Mangas · July 2017

I like my Cummins Onan.

High quality, water cooled propane unit. They warrantied mine for off grid. So many hours if I remember correctly.

Vic · July 2017

Hi Paul,

IIRC, the Xantrex XW MPPT 80- 600 (is that the number ...?) has no front panel controls allowing ANY charge parameters to be set, and has NO LCD display. SO, the customer needs either the SCP, or the Combox (has been a long time since I looked in detail). As is fairly customary, this CC's Default Absorb, Float and EQ voltages are quite conservative, and do generally not fit well with Flooded batteries, and the proposed 1,000 Ah battery is most likely Flooded. (The SCP may well now be discontinued)

AND, if one has the SCP only, then you need another doodad to Implant new Firmware. Some of this may have changed ... perhaps the SCP has been replaced by the Combox.

If one had an all-Schneider system, the extra thingies would not seem (to me) SOOOooo expensive, but when using only the XW 600 V CC/s, thingies make these CCs seem a bit expensive.

Fine on the Grid being too far away. This system looks like it will be quite capable.

All just my opinions, Vic

Dave Angelini · July 2017

The SCP is written in the new Conext Bridge manual so I would say it will continue to be out there for a very long time. It is a value in that it does not depend on a computer and should be specified in any offgrid system because of that reason. Along with combox, one can go out to the WEB portal Insight and monitor the system anywhere there is internet. The -80-600 will power the SCP also. Solid equipment that will last for the ages.

I almost always use a EU 7000i modified for propane when needed.

Estragon · July 2017

In a remote location, I'd go for a unit rated for prime duty unless access is really easy. In my case, it would need to be barged in or an ice road built, so I'm hoping my 35yr old Onan diesel keeps running for as long as I do.

Anawa · July 2017

I'm afraid that the genset may be operating more often than the intended use and the Honda propane 7000EU makes sense for this application.

I'll check with NAWS on the Xantrex components to be able to set and monitor the charge parameters on the 600-80. Eventually all of it comes down to the buck-a-roos, ease of operation, and equipment integration.

Thanks to to all y'all, again.

mike95490 · July 2017

I use BOTH the SCP and Combox with my XW gear. I set the SCP to monitor generator charge current, and "tweak" with web browser interface of the Combox. Only the Combox or Implanter tool can update Schneider firmware.
What are your winter loads, and your anticipated genset runtimes ? I prefer my 600 RPM genset.

Anawa · July 2017

Mike, 8kw and 1000ah system for the 1,400sf structure with only two people full-time, I do not anticipate the wintertime loads being a problem. Wood stove heating. Fresh water from elevated tank requiring only a booster pump.

The dominate factor is the the hot summer loads and the (desire) for nighttime operating of A/C. Based on my personal knowledge of the folks that will be living there, I suspect the A/C will be operating on a fairly frequent basis. Thus, the genset needs to be reliable.

Just saying......

Backup Generator for 8Kw and 1000Ah Off-Grid System

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