diy solar

diy solar

Trying too hard

Thank you for the link ereams65.
Lots of good info, so much to learn, we are going 48v.

I'm in contact with a company that is putting together a system using SMA 6048.

Agree on reducing usage that we have paired back on the consumption to minimize what we need for power.

Have decided to move my Sea Container so that the 20ft long face will be sitting South / SouthWest.
Big job but it will free up space for the "back yard" and allow a better landscape area for gardening and growing vegetables.
Thinking batteries will be Lead Carbon or second life Tesla car battery.

Have my penstock beam supports drilled and up on the island. Install will start this weekend once I have the 6"
PVC sch 40 pipe painted. Lots of muscle power needed to get this installed. Creek is dry so perfect time for the install.
 
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

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 ?
Just my $.02 — those currents listed for power tools are at least 2X at startup, sometimes much more for a fraction of a second. Modern inverters will shutdown to protect the internal electronics when they sense these overloads. Your best solution may be a hefty, old-school generator to run these tools. It will have enough mechanical inertia to bull through the startup loads and no sophisticated sensors that will fault-out and make beeping sounds.
 
Thank you for the link ereams65.
Lots of good info, so much to learn, we are going 48v.

I'm in contact with a company that is putting together a system using SMA 6048.

Agree on reducing usage that we have paired back on the consumption to minimize what we need for power.

Have decided to move my Sea Container so that the 20ft long face will be sitting South / SouthWest.
Big job but it will free up space for the "back yard" and allow a better landscape area for gardening and growing vegetables.
Thinking batteries will be Lead Carbon or second life Tesla car battery.

Have my penstock beam supports drilled and up on the island. Install will start this weekend once I have the 6"
PVC sch 40 pipe painted. Lots of muscle power needed to get this installed. Creek is dry so perfect time for the install.
May you send a photo or two of this part of the project?
Kind Regards,
Steve
 
Just my $.02 — those currents listed for power tools are at least 2X at startup, sometimes much more for a fraction of a second. Modern inverters will shutdown to protect the internal electronics when they sense these overloads. Your best solution may be a hefty, old-school generator to run these tools. It will have enough mechanical inertia to bull through the startup loads and no sophisticated sensors that will fault-out and make beeping sounds.
I'm in contact with a company that is putting together a system using SMA 6048.

If he gets two SMA SI-6048US, that will provide 22 kW startup surge for 3 seconds, 14 kW for 30 minutes, 11.5 kW continuous.
If PV is AC coupled rather than DC, after that 3 second startup surge the AC coupled inverters will pitch in. Depending on how much PV, could supply 22 kW surge and 22 kW continuous with good sun.

I expect motor surge to be 5x, so 4kW motors should be no problem. With PV, even several 4kW motors running so long as they don't start at the same instant.

None of the tools in the list are big loads. They're all 120V and under 2000W and so will start/run off a single Sunny Island (unless there is a balancing transformer to share load.)

A 48V generator could be used to charge batteries. Would need a battery shunt so Sunny Island can keep track of amp-hours. The generator would have to deliver level of current and voltage that that batteries are supposed to get. An AC generator fed into Sunny Island instead would let it regulate charging. In that case, the AC has to be within the (wider) generator input specs of Sunny Island.
 
We are on an Island with no infrastructure.
No stores, no ferries, no electricity, no natural gas, no postal service, no fuel nada nichts.
We haul all of our stuff with our boat. No such thing as an empty boat ride, always bringing something over.
Have loaded the boat with about 2500lbs of rebar. Slow ride.......and low in the water.

To start we will use 20PV at 320w. System will be 48V.
The Micro Hydro will be in use probably before the PV install is completed.
Speaking to my contact re the use of SMA 6048 with the MH they said getting to control the 2 dump loads with
Lithium battery is harder to do than with Lead Carbon batteries.
Want to keep my set up simple and worry free. Should I just go with Lead Carbon ?
Not sure yet. More to read and learn.

Dinky what part of the project do want pics of ?
 
What exactly are the "dump loads"?

I'm not sure what "Lead Carbon" is about. People do get long cycle life with quality FLA, either forklift batteries or Rolls Surrette.
But if the battery bank is small so cycled 80% every day, I think only lithium would last 10 years that way. Shallow cycle most nights, FLA could be competitive.

How is PV to be connected? DC charge controllers? Or AC coupled with grid tie inverters (e.g. Sunny Boy)? I like AC coupled, several benefits. It will require 240V, either transformer or two Sunny Island.
 
PV will be connected with DC charge controllers. We are off grid, no utility / power on the Island.

Naranda seems to be a popular brand in Lead Carbon. Surette is a good brand as well but believe they are FLA with some carbon.
If using either of these batteries they would be 2V cells so 24 total in the seacan .
I would want 3 days of autonomy in my battery bank so it will be heavy and take up space.
But if the MH works as others have told me batteries probably won't get discharged much.
This is why MH will get installed first.

Micro Hydro requires a dump load.
Micro Hydro will be running 24/7 producing 2000 W of power per hour. This will be for the better part of 8 to 9 months.
On a sunny day in Sept we will have 20 panels producing 6400 W for say 6 hours = 38400
That same day the Micro Hydro can be producing 48000 W , total PV & MH may be as high as 86400 W.
Once the batteries are fully charged I need to divert the excess power to a "dump load".
Dump load will be electric hot water immersion heaters in my 2000L hot water tank.
My heating system is Hydronic in concrete floors, crawls space slabs and interior concrete walls.
Once the heating systems has reached it's target temp, then need to divert to a second dump load.
Second dump load will be an out door patio heater or large baseboard heater on the patio to shed the excess power.

In Dec we will have days of relentless rain, creek will be raging with water and sun won't shine sometimes for 10 to 14 days.
This is why we have the Micro Hydro set up for the shoulder season.
 
We are on an Island with no infrastructure.
No stores, no ferries, no electricity, no natural gas, no postal service, no fuel nada nichts.
We haul all of our stuff with our boat. No such thing as an empty boat ride, always bringing something over.
Have loaded the boat with about 2500lbs of rebar. Slow ride.......and low in the water.

To start we will use 20PV at 320w. System will be 48V.
The Micro Hydro will be in use probably before the PV install is completed.
Speaking to my contact re the use of SMA 6048 with the MH they said getting to control the 2 dump loads with
Lithium battery is harder to do than with Lead Carbon batteries.
Want to keep my set up simple and worry free. Should I just go with Lead Carbon ?
Not sure yet. More to read and learn.

Dinky what part of the project do want pics of ?
Micro Hydro please?
Thanks,
Steve
 
PV will be connected with DC charge controllers. We are off grid, no utility / power on the Island.

The micro hydro might be best with a DC dump load. That should reliably put a load on it, independent of what's happening with AC and inverter. That should kick in if charge controller doesn't need the power and RPM/voltage starts to rise. Wind systems also used that.

Since you are going to use Sunny Island, consider AC coupled grid tie inverters (Sunny Boy or others with frequency-watts function) instead of DC coupled charge controllers. Sunny Island will control them by raising frequency. Up to 61 Hz they deliver 100% of power, linearly ramping down to 0% at 62 Hz.

When batteries are full and there are no loads, frequency will sit at 62 Hz. If a motor starts, Sunny Island produces surge current to start it, then lowers frequency until Sunny Boy picks up 100% of the load or delivers 100% of what it has available. Sunny Island then has up to all of its output available for the next surge. This puts battery charging under the control of Sunny Island (which can follow instructions of a BMS such as REC which communicates.)

The grid-tie inverters are 240V. Sunny Island is 120V, so you either need two or a transformer. One 6kW Sunny Island can handle up to 12kW of Sunny Boy, and both contribute to the AC power available.

Off-grid you an use old-stock GT inverters which may be available cheaper. Current model I usually see listed around $1700 for 6kW or 7.7kW.

If micro hydro is DC coupled, you would use a battery shunt so Sunny Island knows how many amp-hours go to battery. That charge controller will do its own thing, so whatever current it wants to deliver will happen. Make sure DC coupled sources are no greater than the charge current you want for your lithium or lead-acid battery. Sunny Island will measure that and regulate the total current battery receives by deciding how much current to give it from PV sources.

With mostly AC coupled sources, you can have the battery get exactly the charge current you want, which might be 0.12C for a forklift battery. Without a system that regulates battery current, battery is charged at higher current sometimes, lower current when inverter is powering loads. Having regulated charging lets you way oversize PV array. Mine could deliver 0.5C, but I have it regulated to 0.2C for AGM.
 
Thanks Hedges
Can you clarify AC coupled grid tie inverters. We do not have a grid. I'm confused.
Does this mean the Sunny boys turn DC for PV to AC before it goes to Sunny Island ?
 
Thanks Hedges
Can you clarify AC coupled grid tie inverters. We do not have a grid. I'm confused.
Does this mean the Sunny boys turn DC for PV to AC before it goes to Sunny Island ?

Yes.
Sunny Island creates an "island grid"
Grid tie inverters see that grid and deliver power to it. But if they are just UL-1741, they deliver 100% all the time, which doesn't work well.
If they are UL-1741SA with "frequency-watts" or most current and older Sunny Boy, they have a setting where they ramp down power as frequency rises, which works well with Sunny Island (and several other brands which now have same feature.)

As for the DC coupled, if you use Midnight Classic charge controllers, there is a data interface available. That lets Sunny Island read amps (so no shunt needed) and set constant-voltage setting. But I don't think it can regulate constant current.

If you have other DC coupled sources, or if you have DC loads, then a shunt would be needed. (If you use Midnight with data interface as well as a shunt, needs to be connected correctly so it doesn't double count.)


 
Latest system diagram for US only shows AC coupling


For European model, still shows "Sunny Island Charger" in 3-phase diagram. Midnight works the same. It also works for the US model.


Sunny Island is about $1/watt retail (but there are some liquidation bargains due to a 3rd party that bought many.)
Sunny Boy about $0.25/watt retail.
New old stock Sunny Boy I've sometimes found for $0.10/watt
Midnight Classic is about $0.20/watt

Something else you would need if 100% AC coupled, useful if part AC coupled and part DC coupled, is a "load shed" relay. My Sunny Island commands disconnect of loads at 70% DoD of my AGM batteries. That leaves the AC coupled Sunny Boys connected to provide charging when the sun comes up.

Each Sunny Island has two relays, and there are about 16 available functions. One is generator start. Two are SoC based, to connect/disconnect loads. Several others, including fan for high battery temperature.
 
Mike...I have the system Hedges is referring to. I bought a DC trailer back in January so I could pirate the 2 SI inverter/chargers and the FLA batteries 1020ah to compliment my Sunny Boy ground mount. The front 72x30x12 aluminum cabinet on my H trailer has 2 Sunny Islands (6048), Midnite solar 250 classic controller, combiner and a breaker box with two 50's amp double pole and a 20 amp single pole breaker for two 120v GFCI plug ins inside cabinet and a 500a/50mv shunt. I DID NOT disassemble the cabinet hardware, cabinet intact I just ran my wires into the cabinet and wired one hot to each Sunny Island (Master and Slave) (neutral and ground) ...VOILA! Ready to go...
AC wired (8awg) the cabinet to my standing ground mount 6400 watt array with the latest version Sunny Boy 5.0 kw-41. It's so damn simple and they (SI & SB) work flawlessly together. DC connected is not the way to go.....I just wish I would I have bought a 6kw because the wiring gauge requirements are the same...I do not know why people mix brands...What I have is plug and play. I really don't need to even monitor it...Go to facebook and join DC Solar Auctioned trailer forum. about 500 members. You will see what I am talking about. Some members are selling the entire cabinet for about 5 grand or thereabouts.....and there are many posts with install issues resolved....
 
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Road glide -

The DC Solar trailer has Sunny Island and Midnight. In some cases a generator too, but you could always feed an AC input to them.
Sunny Island needs to know about all current into/out of the batteries if it is going to manage their state of charge.
Does the trailer have a data interface between Sunny Island and Midnight?
Does it have a battery shunt connected to Sunny Island?
If you still have DC coupled PV through Midnight and you add AC coupled through Sunny Boy, I think one or the other, data interface or shunt, is needed.
If only AC coupled PV and AC input to Sunny Boy, then neither is necessary. (But you do need to avoid over-discharging battery because it will never wake up. I use a load shed relay for that.)
 
Road glide -

The DC Solar trailer has Sunny Island and Midnight. In some cases a generator too, but you could always feed an AC input to them.
Sunny Island needs to know about all current into/out of the batteries if it is going to manage their state of charge.
Does the trailer have a data interface between Sunny Island and Midnight?
Does it have a battery shunt connected to Sunny Island?
If you still have DC coupled PV through Midnight and you add AC coupled through Sunny Boy, I think one or the other, data interface or shunt, is needed.
If only AC coupled PV and AC input to Sunny Boy, then neither is necessary. (But you do need to avoid over-discharging battery because it will never wake up. I use a load shed relay for that.)
At first prior to summer heat I didn't even have MS connected. I was just AC connected SB to SI's. But after July 20th with the heat demands (Air conditioning running and 10-20% less output from array due to extreme summer) I wired the MS back into the system (10-240 panels on trailer) to help with the battery draw down. There was a shunt already in the cabinet 500a/50mv that I commissioned (pg 73)according to the SMA SI manual. There is no data interface. The Midnite and the SI's are 2 separates. They do not talk to each other or communicate. The SI as you know takes energy and takes care of load, then batteries. The midnite has a separate (6awg?) from it's combiner out to the Fork lift batteries.

Apologize for hijacking the thread but i do have a question for you....I have 5 left over 320w Jinko premiums that I want to add to my array but facing SE to gain more early am production. I have 3 strings 8-6-6 (your advice last fall..LOL). I can add the 5 to one of the 6 strings and NOT be over 600v around 550V. Can I do that wired in series with the orig 6? VOC 46.4
 
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Mike...If you end up with a SMA system. That is 2 Sunny Islands and a Sunny Boy inverter you WILL need to configure the Sunny Boy inverter upon initial commissioning to "ISLAND 60hz" before 10 hours of use. Otherwise it will lock you out and then you will need a grid guard code...
 
If Midnight puts its current through the shunt, then SI can account for it. Not previously commissioned, you say? Maybe they did on the generator equipped units.

550Voc from panel specs is within spitting distance of 600V. I would give 16% headroom if not doing any math. Get the temperature coefficient of Voc from data sheet and record cold for your location, make sure it still remains under 600V.

Do you have strings in parallel on a single MPPT? If so, need to be same voltage or you lose out on production. Maybe even dump current into shorter panel.

With the various current limits of the newer sunny boy, when I considered it I would have connected all three MPPT in parallel and then multiple PV strings of different angles in parallel. At least for the current specs of the PV panels I was using.
 
If Midnight puts its current through the shunt, then SI can account for it. Not previously commissioned, you say? Maybe they did on the generator equipped units. ( Nope, just 2 wires from shunt to Master, nothing but temp sensor (phone type wire directly into MS CC and 6awg PV in and 6awg out to forklift battery via combiner)(It probably was commissioned but I redid it just to be safe)

550Voc from panel specs is within spitting distance of 600V. I would give 16% headroom if not doing any math. Get the temperature coefficient of Voc from data sheet and record cold for your location, make sure it still remains under 600V. (That would be 4 panels at 505v and I will recalc cold coefficient and recheck like I did last fall)FYI was very conservative on engineering my system...so far 10 months everything perking along...

Do you have strings in parallel on a single MPPT? If so, need to be same voltage or you lose out on production. Maybe even dump current into shorter panel. (All 3 strings are wired in series into A,B,C mppt ports...String A (8 panels) is around 371 volts and the other 2 (B & C) (6 panels each) are 278 volts. Been working great)

With the various current limits of the newer sunny boy, when I considered it I would have connected all three MPPT in parallel and then multiple PV strings of different angles in parallel. At least for the current specs of the PV panels I was using.( :unsure: Reflecting and thinking on that one, I believe you have many more panels then I?)(I believe in my SMA SB manual it refers to multiple parallel strings into A & B ports and C for series. Got to read that one again.)
 
Was 8-6-6 because a couple different brands?
Are you considering 8-11-6? How about 8-8-9, or are the angles wrong?

I wanted to way over-panel (like 50% over), putting two strings into each input. Each string of two orientations, bringing peak current back down to what it could handle.

I use 8, SunPower 327W panels per string, which stays under 600V. That's about 2500W STC.
With the 6000US and 8000US I got I can do pretty well with that, using 4 strings of two orientations. The 5000US, doesn't seem such a great fit; for now just have two strings.
 
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