Off-grid solar for new development (Campground+Two Yurts), thanks for any help!

cdnorth

New Member
Hello everyone, I've asked a few questions on here and have had some very helpful advice and have learned a ton so thank you. As we're starting to finalize our off grid solar design, I wanted to ask for any input as it would be tremendously helpful. We are designing a property that will have two yurts (one for us and one that we will use as a short term rental) and one small campground development (no RV sites, permitted for 12 sites total, will be "glamping" where we provide lights and some minimal electrical connections for each site). We will be starting by building our yurt, a central restroom facility, and 4-6 sites and then developing the rest in the future. We discussed with a solar contractor in our area and he proposed a Radian system that seems to be fairly robust. I'm not sure if it is overkill and I wanted to get any thoughts I could. Realistically, we don't have the budget to put in the system he is proposing. He is also proposing one system for the two yurts (the smaller system attached) and a separate system for the main facility (larger system attached). I'm thinking we can certainly save some money by having one robust system to handle everything but we are having him provide a quote to run electrical from the main facility to the yurts so that is to be determined. Sorry for the long post, just wanted to give all information in case it is useful.

My questions are as follows:
1. When sizing these systems, how can I determine what diversity to use? I've listed out every component I can possibly imagine being plugged in and it seems highly unlikely or impossible that everything will be plugged in and on at the same time.
2. I'm thinking we may have to go with less expensive equipment to minimize costs. 3xMPP 6548 would seem to work well on paper. I understand that these are less expensive and I'm sure the Outback equipment is better but what benefits would we truly be gaining by going that route? $27k vs. $5k is a large difference for these pieces of equipment, we may not have much option due to budget but I want to know if there is anything else that someone would recommend or if there are any major downsides.
3. For batteries, we were recommended to use Crown batteries which we are not necessarily opposed to. I've done quite a bit of research into LiFePO4 and it seems to be a solid chemistry. If we go with EG4 batteries by signature solar, I believe they are cost competitive and may be a good option. I discussed these specifically with him and he was concerned by the recommended 30A recommended discharge and was saying we may need to have more batteries to account for this. He did say that we can certainly go above this but that it may decrease the lifespan. Is this something we should be very concerned about? Again, I'm not sure that we will be really approaching extremely high wattages very often but I definitely don't want to harm the batteries greatly.
4. Is there a real difference between solar panels? The ones that were quoted were significantly more expensive than what we are seeing on signature solar or similar and I can't imagine that there's much of a difference. I'm sure this is just what he's the most comfortable installing and I've asked the question and I'm sure he won't have a problem installing any type. I'm just curious if there's anything we should be keeping away from.

Anyway, long story short, I am suggesting that we put in (3) MPP 6548's, (12) EG4 5kwh batteries (am tempted to do less but this may be realistically what we need), whatever panels we settle on but somewhere on the scale of 12kw and a generator for backup. We're aware that this isn't going to be cheap but having two separate systems as quoted was far higher than we were anticipating. How does all of this sound for the loads we are showing? Oversized, undersized, or a combination of the two? Definitely looking for a shake down so if all of this looks terrible, let me know your suggestions and thanks so much in advance!
 

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smoothJoey

Scary!
How close are the structures?
Just trying to determine if a central 120/240VAC power house can distribute to all the satellites without excessive voltage drop.
I'm assuming you require 240VAC, confirm?
 

smoothJoey

Scary!
Since you have an odd number of units I'm guessing that one will be master and 2 subordinate all capable of producing 120/240VAC.
But only the master can do so independently?
 

cdnorth

New Member
How close are the structures?
Just trying to determine if a central 120/240VAC power house can distribute to all the satellites without excessive voltage drop.
I'm assuming you require 240VAC, confirm?

Hello, the yurts will be 50-100 feet from eachother and the closest one is about 300 feet, maybe a little less from the main facility. Again, we will be building out one of the yurts first and then the second in the future but the total shown in that spreadsheet is for both of the yurts. Currently, everything we have designed is 120V. Hopefully this helps to clarify and thanks for the time in looking at it!
 

smoothJoey

Scary!
Hello, the yurts will be 50-100 feet from eachother and the closest one is about 300 feet, maybe a little less from the main facility. Again, we will be building out one of the yurts first and then the second in the future but the total shown in that spreadsheet is for both of the yurts. Currently, everything we have designed is 120V. Hopefully this helps to clarify and thanks for the time in looking at it!
You want to design for the finished development.
I'm going to guess the maximum wire run is 400 feet one way.
Would need to no the distribution voltage and continuous amp rating to work out the voltage drop.
 

cdnorth

New Member
You want to design for the finished development.
I'm going to guess the maximum wire run is 400 feet one way.
Would need to no the distribution voltage and continuous amp rating to work out the voltage drop.
Hello,

I would think 400 feet would be safe. I'm assuming we will extend enough power for both yurts to the first and then when we build out the second in the future, just extend from the first unless it would be easier to only do the first and then extend a new line from the main facility when we build out the second? So if we have 11188 watts max calculated and half that would be for each yurt, that would be just under 50 amps each or 100 amps total at 120V correct?
 

smoothJoey

Scary!
Hello,

I would think 400 feet would be safe. I'm assuming we will extend enough power for both yurts to the first and then when we build out the second in the future, just extend from the first unless it would be easier to only do the first and then extend a new line from the main facility when we build out the second? So if we have 11188 watts max calculated and half that would be for each yurt, that would be just under 50 amps each or 100 amps total at 120V correct?
So you just doing 120VAC not 240VAC, confirm?
 

smoothJoey

Scary!
So you just doing 120VAC not 240VAC, confirm?
Suggest you have 1 trench but separate separate breakers and circuits for each yurt.
That is assuming the topology makes sense.
Is it not possible to do a hub/spoke network with the power house in the center?
 

smoothJoey

Scary!
Correct, we do not plan to use 240V.
11188 watts / 120 volts = 93.233333333 amps
93.233333333 amps
800 feet round trip
120 volts

to get under 3% voltage drop you will need to go larger than 4/0 awg pure copper wire.
That is ~4800 feet of very expensive wire to energize the furthest yurt.
I suggest you check the price of copper and re-evaluate.
 

cdnorth

New Member
Suggest you have 1 trench but separate separate breakers and circuits for each yurt.
That is assuming the topology makes sense.
Is it not possible to do a hub/spoke network with the power house in the center?
We could likely put a powerhouse in the center but I'm not sure of the additional cost of the additional building. We were assuming that because we are already adding a new main building, it would be less expensive to add square footage in that, especially because that facility requires more power than both yurts together.
 

smoothJoey

Scary!
We could likely put a powerhouse in the center but I'm not sure of the additional cost of the additional building. We were assuming that because we are already adding a new main building, it would be less expensive to add square footage in that, especially because that facility requires more power than both yurts together.
Suggest again that you look at the price of copper and re-evaluate if necessary.
 

smoothJoey

Scary!
A 120VAC RV has a 30amp supply which is 2880 watts continuous.
A 120/240VAC RV has a 50amp supply which is 9600 watts continuous.
 
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