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Back up generators for mpp solar lvx6058 system

Lstyles

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May 31, 2021
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I am setting up an off grid solar home and think using two mpp solar lvx6058s to provide 120/240 power seems like a good approach. I would like to have a back up generator for times when sun is sub-optimal. The mpp site suggests using inverter generators as the power is cleaner. I am thinking that I need a fairly large generator (5000-10000 watt) as system will be large with solar array of 10-15kw and battery capacity 20-30kwh. Is my tHinking correct? Can anyone suggest compatible generators for these 6058s?
 
I would consider "built in" gensets. Likely diesel likely in the 10Kw or larger size. These are hard wired, support remote 2 wire starts, can be programed for monthly excersise if needed, remote mount large fuel tanks. All the things you want for a large permanent off grid install.
 
Will the “built in” type of unit work with the 6058s? i saw some a general units in 7kw size that were reasonable price and figured they would be large enough to cover rare circumstance of inadequate solar. Our home will be in Baja so sunlight is plentiful year round.
 
I am thinking that I need a fairly large generator (5000-10000 watt) as system will be large with solar array of 10-15kw and battery capacity 20-30kwh. Is my tHinking correct?
Does it need to be that large? It just needs to get the batteries up to charge right? It's a supplement to whatever power the PV can supply. Does it matter if it takes a bit longer to do that or do you really need to get your batteries from zero to 100% in two hours?

What is the typical power draw of the off-grid home?
 
I am not sure how big it has to be and would actually rather go as small as possible because I don’t anticipate it will get used much. As you mention it’s to supplement the PV not to provide whole house back up. I should mention this will be a vacation home in Baja so PV power is pretty reliable/plentiful year round. Also, it will be easy to limit our power usage if it seems like we will have reduced PV power generated (e.g. use less air conditioning). I think what’s most important is that it is compatible with the LVX 6058s and that it can be set up so that it automatically runs if battery gets too low. This would probably only occur when we are not there but when guests/family visits and are not familiar with system like we are. Any suggestions for generators that would serve this purpose and be compatible with 6058 and automatic.
 
The way I did is to multiply the preferred charging rate X 2X for generator size.

What battery chemistry do you have? For lead-acid, the preferred rate is 1/8th C. For AGM, 1/5th C, and Li, maybe 1/4th C.

So, assuming you have a 30,000W lead-acid battery bank you want (30,000W/8) X 2X = 7500W generator.

Keep in mind that some inverters can be fussy about the quality of power they accept. They will look at the voltage, frequency, and the level of distortion, and determine if the generator power is "qualified" to supply power to the inverter. It will be easier for a generator to qualify if it is not at the ragged upper range of it's output, so larger is better than smaller in the equation I gave above. Maybe 3X will be better than 2X; it depends.
 
The literature on the 6048 did mention that the inverter generators are preferred because the power from them is better. If I use the equation you propose above for my lithium battery bank of 20-30 kw then I would need a 10-15kw generator which seems like overkill for a generator that would only used occasionally to supplement a temporary decrease in PV power. Here is what is on the Mpp site:
1629416348601.jpeg

Has anyone firsthand knowledge of a generator that has worked with the lvx6048?
 
While mine is not that specific model, it's of the same family of Voltronic-type inverters. Pretty sure my Yamaha ISE3000EF inverter generator works just fine as a substitute for grid supply. But I'll test it again a bit later just to be sure.

At least you have specifications on the AC input you can use when shopping.
 
Generator needs to supply a 120/240v output. 2 hots, a neutral and ground.
 
That’s correct…I have heard that most larger generators can do this.
I am going to repost my question under the off-grid sub-forum as I think it might be better placed there…plus I have a couple of more questions.
 
F6829B92-F7E6-494D-BC0E-9372E3DA5AB0.jpegI have a Westinghouse 9500 was about $1000 hooked up to my growatt 12k and the above pic is what it will charge at
 
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