Putting the pieces together. Mexico community building

[brushmrw]

Greetings,
I’m looking for recommendations on putting together a somewhat large, scalable Solar system

1. This is a privately owned community center in Baja Sur
2. They have grid power
3. Currently have 20+ 250 watt panels on the roof
4. They bought 2 pow 120 volt, 3000 watt, 24 dc volt inverters which I don’t think will help much.
5. Looking to supply as much 240 VAC energy as possible to the building for daytime operations and storing a reasonable amount in a battery bank for overnight use

Requesting recommendations on 240 VAC inverters/chargers 12,000 (watt or so) that can be scaled up as funds allow. Also battery recs. She currently has 2- CHINS LiFePO4 Battery 12V 300Ah Lithium Batteries

Let me know what the brain trust thinks

Best
Bill

 

[Rocketman]

What kind of loads are you running?

I would use a 48v stuff. My answer is usually Victron stuff, and while it would make a great system, it would be much more expensive.

I don’t know enough about the AIO(all-in-one) to give a good recommendation.

For batteries at 48v the best thing is to have 48v batteries w/48v bms’s. If you don’t want to diy - the rack mount batteries seem really good. You could get 2 more of your current battery and then hook all 4 in series to start your battery bank (assuming they can be hooked up in 4s).

 

[DIYrich]

Cover an acre of land with panels.

Space constraints. Largest potential draw. Split or 3 phase power.

You can scale up to 9 sol-ark 15k for 135kW of continuous power. Although at 30kW the commercial units make more sense.

 

[brushmrw]

What kind of loads are you running?

I would use a 48v stuff. My answer is usually Victron stuff, and while it would make a great system, it would be much more expensive.

I don’t know enough about the AIO(all-in-one) to give a good recommendation.

For batteries at 48v the best thing is to have 48v batteries w/48v bms’s. If you don’t want to diy - the rack mount batteries seem really good. You could get 2 more of your current battery and then hook all 4 in series to start your battery bank (assuming they can be hooked up in 4s).

Day to day probably 10-25 amps 240volts. If there are classes or other activities it could spike to 50-70 amp with multiple a/c units running.

I’ll look at Victorn, she’s on a bit of a budget. I assume then I’d need a charging solution if the Victron isn’t an all in one? If the delta isn’t too great we could swing that direction.

Plenty of room in the bodega for 4+ batteries.
Thx

 

[brushmrw]

Cover an acre of land with panels.

Space constraints. Largest potential draw. Split or 3 phase power.

You can scale up to 9 sol-ark 15k for 135kW of continuous power. Although at 30kW the commercial units make more sense.

No huge space constraints. Money is the constraint.
Split phase 240vac
Big draw would be 50-70 amps 240v Normal 10- 25 amp

 

[Tomthumb62]

Not one of the resident experts, but I have learned a TON reading this forum a lot over the last 18 months.

I can't see any reason why you would go with less than a 48v system with 48v batteries. The two current Chins batteries could be extras for emergencies, but either DIY multiple 48v batteries or buy them pre-built at $1500-1800 per 48v 100Ah (4800Wh). I think you can build them for about $800-1200 (maybe less, I'm not really in the know of current pricing), cost will go down once you buy in bulk the cells, wires, tools and BMS's. If you buy from China, you can get the best price, but you gotta know who/where to buy from so you don't get scammed and probably will need to wait for it to ship, 2-6 months, depending upon the source.

With a 48v system, panels would need to be configured to get 60v or more per string of series, the higher the voltage you can go, the better. Some charge controllers can accept as much as 2 x 500v (two separate inputs of up to 500v each, but you CANNOT go over the 500v, better to stay down around 450v in such a case.) Higher voltage will allow you to use smaller (less expensive) wire to run the panels to the charge controller(s).

 

[DIYrich]

70 amps at 240v, you are looking at two Sol-ark 15k or EG4 18k. You could do it cheaper in phases with Growatt. 48v system for anything over 3kW.

Start with a 48v inverter. Then double the panels. Then diy a 14kWh battery for about $3,000.

Then add more panels, and batteries.

 

[littleharbor2]

Money being a factor, you really need to build your own LFP battery. You pretty much get double the storage capacity for your money.
AIO inverters also give the best bang for the buck.

 

[Q-Dog]

What are the current panels doing? Are they grid tied?

 

[DIYrich]

Buy 2 more of the same battery, and put in series to make 48v. If you need more batteries after that, buy the individual 3v cells and a BMS.

BTW: plan now for the eventual build out. Put in wireways, bus bars, power distribution bars, space on the wall, where batteries go, etc. Easier to do it once upfront than to move things around as you build it out.

 

[brushmrw]

What are the current panels doing? Are they grid tied?

The panels are currently sitting in the sun on the roof, not connected to anything. From what I understand grid tie (feedback) is not allowed on this installation yet I know it’s allowed in mexico so that a discussion down the road.

 

[Quattrohead]

Sol-ark 15k or EG4 18k will be a good fit for your situation.

 

[DIYrich]

The panels are currently sitting in the sun on the roof, not connected to anything. From what I understand grid tie (feedback) is not allowed on this installation yet I know it’s allowed in mexico so that a discussion down the road.

Feedback may need a different meter and agreement with power company. You can install with no grid feedback.

 

[OffGridForGood]

I’m looking for recommendations on putting together a somewhat large, scalable Solar system

1. This is a privately owned community center in Baja Sur
2. They have grid power
3. Currently have 20+ 250 watt panels on the roof
4. They bought 2 pow 120 volt, 3000 watt, 24 dc volt inverters which I don’t think will help much.
5. Looking to supply as much 240 VAC energy as possible to the building for daytime operations and storing a reasonable amount in a battery bank for overnight use

1. What regulations will apply?
2. What are the requirements for electrical inspections, permits?
3. What are the options for selling to the grid (during the sunny day) buy back at night? (rates that would apply?)
4. Can they return for credit or sell the 24v inverters, to pay for 48v ones?
5. Can a net-zero (battery-less) system be used for this location?
6. When you say -"supply all the 240v energy possible" does this mean 240v only, no 120v needed? please confirm.

 

[brushmrw]

70 amps at 240v, you are looking at two Sol-ark 15k or EG4 18k. You could do it cheaper in phases with Growatt. 48v system for anything over 3kW.

Start with a 48v inverter. Then double the panels. Then diy a 14kWh battery for about $3,000.

Then add more panels, and batteries.

Please check me on this example:

The Sol arc 15kw inverter accepts 26 amps per mppt, 425 volts.
Panels are 250 watt, 8.85 amps, 37 volts.
2 arrays - 5 in series/2 parallel =20 panels

Total output
5000 watts, 188 volts, 35 amps +-

 

[brushmrw]

1. What regulations will apply?
2. What are the requirements for electrical inspections, permits?
3. What are the options for selling to the grid (during the sunny day) buy back at night? (rates that would apply?)
4. Can they return for credit or sell the 24v inverters, to pay for 48v ones?
5. Can a net-zero (battery-less) system be used for this location?
6. When you say -"supply all the 240v energy possible" does this mean 240v only, no 120v needed? please confirm.

1. Not sure
2. Building is permitted. They made her have two meters. One for clinic, second for apartment upstairs (different rates)
3. She was told no selling power back, yet I know it’s done in Northern Baja.
4. All the gear is over 18 months old. Unlikely able to return. Could sell as unused eBay etc.
5. Not sure (beginner)
6. Sorry we need 120/240. The big current draw are the mini splits AC 240 volt 10 amps.

 

[OffGridForGood]

1.All of N.America use 120/240 split phase, but the electrical regs are different from place to place. The local code requirements 'may' affect what inverters you are permitted to use, and this requirement may be different depending upon how the solar-PV system interacts with the Utility-grid system. Best to find out before spending any (more) money on the project.
2.Apt and Community centre are two separate systems - this may mean using the smaller 24vDC system for the Apt and building a separate system (likely 48vDC for the community centre, assuming bigger loads on the CC)
3. No selling back - so we will need to plan batteries for night, or use utility at night. Batteries are expensive.
4. If the smaller inverter will work for the Apt, then it may be best to just keep it, although 24V has limitations, and it would be "nice" if the Apt and main CC had the same battery voltage, but not essential.
5. A net Zero system would feed energy from the PV system to the main electrical panel, but only up to the amount of energy being used by that panel, ie it never exports power to the utility. These types of systems are easier to set up, but the utility can be the problem, since they are concerned with the posibility of power feeding into their lines, with their staff working on those lines. (in my area it is very difficult to meet all the utility requirements for a net-zero system economically, so I gave up on this as a solution early on). In your situation that may not be such a big hurdle, and a net-zero export option could be a great way to cut the costs of batteries, and simplify the installation between PV system and Utility system. I recommend you inquire with local electrical to see if this is an option.
6. understood 120/240. Can you identify the typical max load (for the Apt, and separately for the CC) so we can suggest equipment sizes?

 

[brushmrw]

1.All of N.America use 120/240 split phase, but the electrical regs are different from place to place. The local code requirements 'may' affect what inverters you are permitted to use, and this requirement may be different depending upon how the solar-PV system interacts with the Utility-grid system. Best to find out before spending any (more) money on the project.
2.Apt and Community centre are two separate systems - this may mean using the smaller 24vDC system for the Apt and building a separate system (likely 48vDC for the community centre, assuming bigger loads on the CC)
3. No selling back - so we will need to plan batteries for night, or use utility at night. Batteries are expensive.
4. If the smaller inverter will work for the Apt, then it may be best to just keep it, although 24V has limitations, and it would be "nice" if the Apt and main CC had the same battery voltage, but not essential.
5. A net Zero system would feed energy from the PV system to the main electrical panel, but only up to the amount of energy being used by that panel, ie it never exports power to the utility. These types of systems are easier to set up, but the utility can be the problem, since they are concerned with the posibility of power feeding into their lines, with their staff working on those lines. (in my area it is very difficult to meet all the utility requirements for a net-zero system economically, so I gave up on this as a solution early on). In your situation that may not be such a big hurdle, and a net-zero export option could be a great way to cut the costs of batteries, and simplify the installation between PV system and Utility system. I recommend you inquire with local electrical to see if this is an option.
6. understood 120/240. Can you identify the typical max load (for the Apt, and separately for the CC) so we can suggest equipment sizes?

Thanks a mil for the input/education
The primary objective is to use the existing panels to offset as much energy cost durning the day. Southern Baja is super hot, so they get lots of sunshine and need lots of AC. The CC is rarely used at night.
The net zero concept is exactly what I’m thinking is needed at this point. I’ll inquire about the code requirement and inverters.
Given the smaller inverter is only 120v and both panels for the CC and apartment are 240v it seems troublesome to create a separate “120v panel” to utilize that inverter.
I’ve only been to the building twice. We run free medical dental clinics there. I did not measure the loads, so I’m estimating.

At this point I’d like to get her up and running, powering the CC with the existing 20 panels, and supplement with grid power as needed.

Batteries are less important initially. The “night load” is the apartment. The grid power is less expensive and the load is minimal.

Thanks for helping me drill down on priorities.

 

[littleharbor2]

Up north Here in San Felipe the POCO reduces the electrical rates in the summer so the people can run air conditioning. Friends have told me they pay about 25 USD a month in the summer. Of course where I live, in the South Campos . we're off the grid. It ends about 15 miles up the road.

Does your POCO discount rates in the Summer?

 

[brushmrw]

Up north Here in San Felipe the POCO reduces the electrical rates in the summer so the people can run air conditioning. Friends have told me they pay about 25 USD a month in the summer. Of course where I live, in the South Campos . we're off the grid. It ends about 15 miles up the road.

Does your POCO discount rates in the Summer?

Good question.
Even at a discounted rate when you run 7-9 mini splits for two days (typical clinic) it adds up fast.
You’re a pretty good lick beyond San Felipe. We fly that coast all the time. This facility is in Constitución mid peninsula past Loreto.