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Best Solar/battery/inverter topography for grid assisted off-grid in Costa Rica

l00semarble

New Member
Joined
Jan 1, 2022
Messages
150
Hey I'm new here. Hello to the group.

I am building a medium sized 3 bedroom "luxury" home in the jungle in Costa Rica. We have US spec 120/240v split phase power here. I have done a load inventory but it is somewhat hypothetical based on all the appliances and such that I will buy and spec for the home. I do have real data from my current house where we have averaged around 1,000kwh/mo during occupancy.

One of the killer loads in current house is a single speed pool pump that is used 365 days/year. The new house is a bit larger and will have a garage/workshop but we will spec all LED lighting, highest efficiency appliances including the best possible variable speed pool pump and we will spec a rooftop non-electric solar water heater. The new house will have mini-split air conditioners in the 3 bedrooms but they would not be regularly used as the house has an open air design and is at an elevation that makes it unnecessary but they may be used for humidity control if/when we are away from the house or to briefly cool/duhumidify a bedroom bedtime if it had been closed up and stuffy. Cooking can be either electric or I could do a propane stove but I have to hump my own propane bottles if I do this which is not a deal breaker but this is an hassle and an energy cost that I would like to avoid if possible.

I'm still working the spreadsheet but I figured I will need about 900 kwh/mo.

Electricity here is expensive at about $0.15/kw so part of the goal is to reduce energy costs to at/near zero for my retirement but the other problem is that the grid at our remote location is unstable and causes constant problems with appliances. We are constantly replacing "motherboards" and "control boards" and small appliances due to damage from voltage fluctuations and frequent momentary outages.

So we want a system that provides cost savings but also protects us from the unstable grid. Exporting to grid is complicated/bureaucratic here and you don't get the full benefit back of the power you export. I'd rather store it and forget export.

I own a a marine electronics/electrical shop and we are a dealer for VIctron Energy but my Victron experience is limited to marine applications. Because I am very familiar with the products and because I can get Victron at wholesale I plan to spec an all Victron system including batteries.

I am working on sizing of solar array and battery bank but I think I will end up with about (at least) 10kw of solar and at least 30-40 kwh of batteries and that much battery basically only gives 1 day of autonomy but I will use the grid like a backup generator and use the Victron system with their Energy Storage System (ESS) setup to use grid if necessary but always optimize self consumption and maintain zero export. Victron has some very flexible/configurable options for their ESS systems and I believe the inverters can act quickly enough (maybe using UPS mode?) to avoid passing through any voltage flucuations or other grid instability anomalies.

i need to consider what Energy Storage System topography and what Victron equipment is going to make the most sense. I was planning a 48v battery bank as it will be exclusively for the ESS system so seems that would be most efficient. To get split phase I plan to use a 230v inverter and a Victron autotransformer but I will also spec as many of my appliances as 240v as possible to keep the AT balanced as possible. I am thinking this is better than using two inverters to make split phase 120/240v but open to any thoughts on that.

So the main choice regarding overall topography is do I use a AC PV "grid tie" inverter (Fronius) on the output side of the Victron inverter or do I just use Victron MPPT controllers and put all PV into the DC side. With the later I stay virtually all Victron. I guess I can check the cost difference and go based on that but I am wondering about the performance difference or what relative advantages/disadvantages there are. I assume direct consumption off an AC PV inverter is technically more efficient than going through an MPPT and a DC to AC inverter so maybe that is the main difference. I guess I would have more total AC wattage available during daylight so I can also make a point of running certain heavy loads like the pool pump or dryer during daylight.

Thoughts?

MPPTs.JPG

OR

Fronius option.JPG
 
More Power to ya for going Solar / for 10kw of solar w at least 30-40 kwh of batteries. Makes mucho sense for Mini-split AC units when the sun is shinning. ... I do not have a specific response to your whole set of project questions (kind of allot to tackle/ suggest you might break it down later) ... To Draw ya out ... Where in Costa Rica are you building? Is your Victron /Marine purchasing business in the USA or Costa?

Re: your: "grid at our remote location is unstable and causes constant problems with appliances. We are constantly replacing "motherboards" and "control boards" and small appliances due to damage from voltage fluctuations and frequent momentary outages." ... I know that one from purchasing small property here in Montezuma area about 15 years ago. Wondering if these appliance problems are mostly on small draw appliances; like PC and/or internet options? or larger amp draw appliances (maybe AC or Washing Machine) ??? ... and if you are near the beach humidity or other normally humid conditions. Asking, as I may have some ideas to pitch you about that. ... Bill
 
More Power to ya for going Solar / for 10kw of solar w at least 30-40 kwh of batteries. Makes mucho sense for Mini-split AC units when the sun is shinning. ... I do not have a specific response to your whole set of project questions (kind of allot to tackle/ suggest you might break it down later) ... To Draw ya out ... Where in Costa Rica are you building? Is your Victron /Marine purchasing business in the USA or Costa?

Re: your: "grid at our remote location is unstable and causes constant problems with appliances. We are constantly replacing "motherboards" and "control boards" and small appliances due to damage from voltage fluctuations and frequent momentary outages." ... I know that one from purchasing small property here in Montezuma area about 15 years ago. Wondering if these appliance problems are mostly on small draw appliances; like PC and/or internet options? or larger amp draw appliances (maybe AC or Washing Machine) ??? ... and if you are near the beach humidity or other normally humid conditions. Asking, as I may have some ideas to pitch you about that. ... Bill

We are in Uvita in the Southern Zone (Pacific side). We are close to beach but at about 1400ft elevation basically up the mounting next to beach overlooking beach. Humidity is an understatement. Salt air is a minor factor up here at this elevation. We use VIctron in marine environments so I have no hesitation about using the gear in this climate/weather. My main business is in the USA but I am starting to do some work in Costa Rica on technology stuff like home security systems and camera systems. I will expand into offering Victron solar/energy storage solutions after I practice on myself and move here full time.

The appliance damage is usually the larger appliances as small technology stuff is easily put on UPSs.
 
To get split phase I plan to use a 230v inverter and a Victron autotransformer but I will also spec as many of my appliances as 240v as possible to keep the AT balanced as possible. I am thinking this is better than using two inverters to make split phase 120/240v but open to any thoughts on that.
Saw a video the other day mentioning just this situation involving auto transformers. The video is dealing with Growatts so not sure if same issue could be present with using Victron. Food for thought at least. The EE's around here can provide more info I am sure.

 
Re your; ... appliance damage is usually the larger appliances as small technology stuff is easily put on UPSs. ... Think UPSs is good idea. I have a Tripplite APS750 connected to a 12v Marine Deep Cycle lead acid Battery that automatically powers my electronics and a few lights, and maybe one fan when the grid goes off, then passes the grid to load when the grid comes back on while three stage re-charging battery. It can handle 1500 Watts from Battery to its' 2 AC sockets (I put strips on em for more plug in options) for maybe 10 seconds. It's been functioning for 10 years without problems. Notice some adjust options to make it more or less sensitive to AC voltage shifting, for when to switch to battery power. I really like it. Re Grid Shifts: I hear my grid Hz shifting sometimes in the mornings via my running a fan. The other hardware I like is the Delta Surge protectors. They seem more economically priced than some others; so I have one for lightening surges, plus another for grid surges. They connect to a big 240v breaker and ground. I heard a huge loud snap one time standing near one during a nearby lightening strike. ...... The other options I think of for larger appliances might be a room with a de-humidifer. I had a couple of Frigidaire units (picked up at Price Club/ SJ area) set at 60% in a couple different 20 foot shipping containers with a hose drain to ground for over a year plus (was gone 1 & 1/2 year since Covid started) ... and my ICE electricity bill for all that time with a small thin upright GE frig dialed down to 1 ... was only about $20/mo. My humidifers can adjust down to 35%, but I think that would show on my bill. 90% is norm without em. ... One other idea I tried was contact cleaner on a circuit board, then a Polyurethane spray in dry room to seal it up better. Sold that inverter to a buddy, so did not see long term result, but thought it was a worthy idea to mention. My two cents of small support ideas ... from sailing options ;+) on my hill above Montezuma on Pacific side.
 
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Sounds like you have it pretty well figured out.
My only suggestion would be dc solar instead of micro inverters. Dc to dc battery charging.
And only inverting once for consumption.
Also, you can never have too much solar.
For cloudy days and unexpected week long rains.
 
Hey I'm new here. Hello to the group.

I am building a medium sized 3 bedroom "luxury" home in the jungle in Costa Rica. We have US spec 120/240v split phase power here. I have done a load inventory but it is somewhat hypothetical based on all the appliances and such that I will buy and spec for the home. I do have real data from my current house where we have averaged around 1,000kwh/mo during occupancy.

One of the killer loads in current house is a single speed pool pump that is used 365 days/year. The new house is a bit larger and will have a garage/workshop but we will spec all LED lighting, highest efficiency appliances including the best possible variable speed pool pump and we will spec a rooftop non-electric solar water heater. The new house will have mini-split air conditioners in the 3 bedrooms but they would not be regularly used as the house has an open air design and is at an elevation that makes it unnecessary but they may be used for humidity control if/when we are away from the house or to briefly cool/duhumidify a bedroom bedtime if it had been closed up and stuffy. Cooking can be either electric or I could do a propane stove but I have to hump my own propane bottles if I do this which is not a deal breaker but this is an hassle and an energy cost that I would like to avoid if possible.

I'm still working the spreadsheet but I figured I will need about 900 kwh/mo.

Electricity here is expensive at about $0.15/kw so part of the goal is to reduce energy costs to at/near zero for my retirement but the other problem is that the grid at our remote location is unstable and causes constant problems with appliances. We are constantly replacing "motherboards" and "control boards" and small appliances due to damage from voltage fluctuations and frequent momentary outages.

So we want a system that provides cost savings but also protects us from the unstable grid. Exporting to grid is complicated/bureaucratic here and you don't get the full benefit back of the power you export. I'd rather store it and forget export.

I own a a marine electronics/electrical shop and we are a dealer for VIctron Energy but my Victron experience is limited to marine applications. Because I am very familiar with the products and because I can get Victron at wholesale I plan to spec an all Victron system including batteries.

I am working on sizing of solar array and battery bank but I think I will end up with about (at least) 10kw of solar and at least 30-40 kwh of batteries and that much battery basically only gives 1 day of autonomy but I will use the grid like a backup generator and use the Victron system with their Energy Storage System (ESS) setup to use grid if necessary but always optimize self consumption and maintain zero export. Victron has some very flexible/configurable options for their ESS systems and I believe the inverters can act quickly enough (maybe using UPS mode?) to avoid passing through any voltage flucuations or other grid instability anomalies.

i need to consider what Energy Storage System topography and what Victron equipment is going to make the most sense. I was planning a 48v battery bank as it will be exclusively for the ESS system so seems that would be most efficient. To get split phase I plan to use a 230v inverter and a Victron autotransformer but I will also spec as many of my appliances as 240v as possible to keep the AT balanced as possible. I am thinking this is better than using two inverters to make split phase 120/240v but open to any thoughts on that.

So the main choice regarding overall topography is do I use a AC PV "grid tie" inverter (Fronius) on the output side of the Victron inverter or do I just use Victron MPPT controllers and put all PV into the DC side. With the later I stay virtually all Victron. I guess I can check the cost difference and go based on that but I am wondering about the performance difference or what relative advantages/disadvantages there are. I assume direct consumption off an AC PV inverter is technically more efficient than going through an MPPT and a DC to AC inverter so maybe that is the main difference. I guess I would have more total AC wattage available during daylight so I can also make a point of running certain heavy loads like the pool pump or dryer during daylight.

Thoughts?

View attachment 78051

OR

View attachment 78052
With the DC coupling Victron system, how you calculate until when you discharge the batteries for sun production to keep Battery reserve for ups?
 
Victron has a very robust and flexible set of Energy Storage System (ESS) parameters that can be adjusted to suit your needs. You can set a reserve or battery floor up to and including "keep 100% charged".

 
Literally just replaced an entire dishwasher due to power related damage/malfunction. It was going to take too long to get the main control board to fix it and we had renters in the house back to back and just had to get a working unit in. So yes, still happening. The new house will be a different story with my solar/battery/inverters.

Of course it isn't all problems here. LOL.

20220501_144904.jpg
 
curious as to what you did. i live in la guacima and have solar and no issues any more with power almost use nothing monthly form CNFL last month as 12,000 colones vs. before about 65,000. i also import solar if you need anything.
 
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