diy solar

diy solar

Trying too hard

Mike 604

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May 9, 2021
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Hello everyone.
First post so please do not flame me.
Have been building my retirement home off grid, on an Island that is boat access only. I'm a GC.
We are now at a stage that I want to get power from my PV instead of the generator.
The build is nearing completion, it has been build on weekend and on vacation time, 7 years now......
Purchased 34 PV panels which are 320w and plan on using a 48v battery set up.
Panels will go on my sea can and also on three ground mounts.
Also have a creek that has lots of water for 9 months of the year. Purchased a micro hydro cross flow type which is 3phase.
This will be producing zero when creek is dry in the summer time but up to 2000w in the winter.
Dump load will be hot water immersion heaters. Have two storage tanks of 1000L each. Each tank has 6 inputs.
Because construction will still be happening/never ending want to power a table saw, compressor and a chop saw as well.
The big decision is which brand of inverter. Doing the math looks like a low frequency inverter is what I should go with.
If something goes down I want to be able to do it at my place instead of lugging unit out of the sea can, onto boat then onto the mainland.
Do I use 2 inverters for redundancy ? One dies I still have power ?
Any suggestions here from this community would be very helpful.
Local suppliers want to sell their gear and want to send people over $$$$$. I want to do most of it myself so if something goes wrong I will be able to solve the issue myselp

Attached a picture from the start of our build, 2014.
 

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Next questions are...
Split phase or single phase?
How much continuos ac wattage?
 
Will need single phase 240v for my septic pumps as my field is about 1000 ft away and 100 feet higher then where my pump chamber is.
When I did an energy audit of our future home I came up with 22k if everything is is on at once except the tools. I cannot see us using that kind of power continuously.
 
Or 3 phase?
"single phase 240v"
Please clarify if you mean one 240V hot relative to neutral, or if you have 120/240V split phase (typical U.S.)
50 Hz or 60 Hz?

I have Sunny Island, which is good for starting motors.
Two Sunny Island would give you 120/240V at 11.5kW continuous, 22kW motor-starting surge for 3 seconds, something in between for various periods.
You've got 10kW of PV. I would set that up as two orientations, so about 7kW peak for more hours.
7kW PV inverter + the Sunny Island would give you 18 kW middle of the day.
Hydro could go to a 48V battery charger. There are also AC coupled options like the PV inverters.

Of course you could set up some sort of a priority switch, so one load is cut out when another turns on.
 
We are just North of Seattle WA.
120/240V 60 Hertz is what we will need. This is called Split Phase yes?
Because of the lay of the land very difficult to make only two towers. We have 45 deg slope where we need to put the PV.
Also large trees on the south side of of our property would shade the PV. Therefore follow the land and no issues of shade.
Will commence research on the Sunny Island Inverters.
Thanks Hedges.
 
Sunny Island has MSRP of about $5000 more or less. But a bunch are being liquidated around $2000 or so. I bought a pallet of them through eBay.
They will work with new Sunny Boy or other inverters that have frequency-watts function. You're off grid, don't need latest functions required for grid-tie, so older models could be the way to go. I've decided to use all transformer type, not transformerless.

Search for DC Solar trailers. They have two Sunny Island, one Midnight charge controller with 2400W of panels (DC coupling), and usually two FLA forklift batteries. If batteries are good (not dried out) it makes a turnkey system that just needs more PV panels AC coupled with Sunny Boy. I've seen some of the trailers offered around $8000. Some come with a diesel generator at higher price. A few people here have bought them.
 
Agree, after reading and watching YT transformer type are the way that I'm leaning
Off to eBay I go.
 
120/240V 60 Hertz is what we will need. This is called Split Phase yes?
Yes.

For fault tolerance you could get 2 inverter[charger]s designed to work in parallel for redundancy.
The generator could also be pressed into service.
 
Not sure of your total power needs but a Schneider CSW 4048 can provide 240 split output and be supplemented by a 120v or 240v genset while still putting out 240v due to the built in auto transformer. May be helpful in your application.

It is heavy LF back breaker.

I bought mine here:


Free shipping, no sales tax and 5% off your first order.

No affiliation other than as a satisfied customer.
 
Thank you guys for the info and clarification.
Joe Ham, interesting website.
Will spend some time looking at their candy store.
Thanks
 
First get the specs and types of motor loads. Those are the hardest to start.
Brush-type motors should be easier, and induction motors are most difficult.
If spec includes LRA (locked rotor amps), multiply by voltage to get watts and the inverter needs surge rating for several seconds at that level.
If that isn't specified, multiply running wattage by 5 to get an estimate of starting surge watts.

A good 5 kW inverter might provide 10 kW surge for a few seconds, sufficient to start a 2 HP motor with 2 kW rating.

If you will be putting in a well pump, those range from large induction motors to VFD driven pumps from Grundfos that would be very soft-starting, no surge.
 
Heading to the Island to work and will check my "heavy" loads.
Where are the Sunny Island inverters made. Still in Germany or in China ?
 
None in China.
SMA did purchase a Chinese inverter manufacturer and for a while assembled a US model Sunny Boy there, with PCB assembled in China and Germany. An article I read said the failures which did occur were in the German made boards.
US Market wasn't interested in Chinese made SMA, and they stopped that. Apparently no longer have majority ownership of that Chinese manufacturer.



I believe at least some components on PCB are German or otherwise European made. It would seem quite likely that some components come from China or other overseas sources; for many, no domestic sources exist and top brands are made in the far east.

At least some SMA inverters for the US market are made in the US and in Canada. Not sure if any Sunny Island ever have been

Unless you want to pay $5000 each, you'll be picking up some new-old-stock. Mine say date of manufacture 11/2017, "made in Germany by SMA Solar Technology AG."

If you get older transformer-type Sunny Boy, my SB 5000US says, date of manufacture 10/2011, "Engineered in Germany, Assembled in Ontario" which likely means PCB were stuffed in Germany. (It was a later transformerless model that had some boards stuffed in China.)
 
I suggest you look into a hybrid arrangement, at least as the initial system:
1. One extreme is running exclusively off the generator. Noisy but easy.
2. The other extreme is exclusively running off solar. Expensive with mega panels and batteries.

Look for an inverter that has inputs for both solar and generator. During normal usage you are quietly running from solar, and times of high demand the generator auto starts plus recharges the batteries.
 
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Sunny Island will give that. Plunk it down with a battery, and you've got AC 24 hours a day. It will start generator when needed, but allows greater DoD at night, prefer to make noise in the day. Small amount of PV DC coupled would help sustain battery. But most PV should be AC coupled, so Sunny Island can regulate charging current. If FLA, stay at optimum 0.15C rating or whatever it should be. If Lithium with BMS, respond to what BMS requests.

PV is pretty economical, although generator is cheaper way to get higher watts and more watt-hours short term. If power consumption during construction is greater than future household power, then makes sense to size PV up to household requirements. I like to do oversize, because cheap, reduce use of generator (grid in my case) during overcast days. if PV goes on roof, can't put in permanent location until construction reaches that stage. But OP is going to have PV on a hillside, so could deploy at least some now. It is actually likely that kWh consumption will be higher for household consumption if A/C is needed, and construction will use less.

Would construction average more than one 1800W Skillsaw running continuously for 8 hours/day? About 3kW of PV would supply that. In the summer, about 10 of OP's panels laid flat on the ground. If he gets a DC solar trailer, its 2400W of panels might be enough. Could add one more string. If it includes the generator that would take care of inclement weather for year-round use.
 
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Thanks for all the replies and suggestions.
The old hand me down PV panels have been a real bonus right now as my two gennies have issues and had to bring them back to the city for servicing. The Honda diesel has 2840 hrs and the Honda gaser has 483 hrs.

The heavy construction is done, concrete poured for walls, roof, roof overhangs, slab on grade and suspended slabs & stairs.

To finish the indoor and various outdoor projects still need
Table saw 120v 15amp
Thickness planer 12v 15amp
Chop saw 120v 14amp
Vacuum/dust collector 120v 13amp
Compressor 120v 17amp
Worm drive saw 120v 15amp
Concrete drill and coring drill 120v 15amp

Luckily since we are typically only there on weekends I only use one tools at a time unless my kids come to help.
There is a good chance that the compressor will start while I'm running table saw with dust collector.
The 10x320w PV panels which are going on top of my seacan will get installed next weekend. The other frames are being cut and fabbed for me to bring up via barge in July.
Have four lock blocks coming up on the same barge for the bases of the ground mounts.
I'm leaning to use as little dino fuel as possible so I'm leaning towards low frequency inverters.
Watching YouTube videos where people are testing inverters it shows that the low frequency inverters are the way to go.
In some cases Dpoz demonstartes that Singneer 2500w Low frequency inverter can start tools where as the 5 and 6000 w high frequency do not have what it takes to start up compressor or chopsaw.

Sunny Boy, Victron, Sigineer are in the hunt. Want two inverters for redundancy.
Looked at the Sol Arc 12k but apparently they cannot start the big tools.
Two neighbors have Schneiders , they have servicing issues, no thanks.

The creek is still with water so have to wait till July before I can install pipes etc for the Micro Hydro.

Looking at a back up diesel generator for a just in case scenario.
While surfing Craiglist last night I saw a 48v DC Honda generator on Craigslist. Is this a viable option ?
 
Looking at a back up diesel generator for a just in case scenario.
While surfing Craiglist last night I saw a 48v DC Honda generator on Craigslist. Is this a viable option ?

Could be. Does it also have an AC output? If not, you would depend on inverter to get AC. An AC generator would provide portable backup power without needing the inverter to work.

If you have DC charging, you might use a battery shunt so system can track state of charge. For instance Sunny Island keeps track of charging it performs (from AC) and any DC charging from Midnight Classic SCC that are linked to it with a data cable. A battery shunt is used to track charging from other sources (which could include your hydro.)

Some 48V generators are hard-wired with positive ground. If so, inverter battery system needs to be compatible with that. One guy here got such a generator. His Sunny Island allowed either positive or negative ground.

If you have an AC generator, it could be fed to the inverter/charger, which would use it to charge the battery. Some models can also add power from battery if AC load is greater than generator can support. (Not all do.) The generator voltage and frequency have to be within range. A mechanical generator will have RPM/frequency that varies a bit with load, hopefully within desired range. If operating poorly, might oscillate out of range and inverter doesn't connect. If an inverter-generator its frequency would be constant, but may or may not work well with some inverters.

Here's a paper from SMA on characteristics of generators, what's compatible and what isn't.
Sunny Island can signal to start a generator, disconnects to prevent backfeed into the generator, starts it periodically to exercise it, etc.

 
Thank you for your help and the info. Have a lot to learn.
Am watching youtube and reading & studying this almost all waking hours when I'm
on the mainland.
 
I’m in the same boat , I’m in year 5 ? I use a out back 36/48 inverter and can run all my tools off it .
I f my compressed starts while I’m using the table saw , I just stop the saw there is no reason to push it
I can run 2 tools at the same time no problem if the sun is up it really works great .
Looks like you are planing to use a lot of power .
You should try to cut back where you can its easer to cut back on usage rather then make more power .
My place uses 2/300 watts at a time so 3200kw to 5000kw a day mostly .
 
One thing to keep in mind, is you need to do your energy audit after converting the numbers you shared above.
For example, the Compressor at 120v AC/17amps will be about 47 amps DC at 48v. If you were to half the 48v into a 24v system you double the amp draw to 94amps, 12v 188 amps etc. Just pointing that out because it will be important to know what voltage your using in your build.
Here's a calculator to help determine your needs.

 
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