Solar Panels in the Tropics

[frankie57pr]

I live in Puerto Rico and I want to set up a solar back-up system for when the power goes out. After Hurricane Maria we were left without power for about 80 days, so I need solar power as a back up because gasoline for my generator got very expensive. I already have the 1500 watt Aims power pure sinewave inverter and the ExpertPower 100 AH LiFePO4 12 volt battery and I ordered the EPEVER 40A MPPT Solar Charge Controller. I plan on using a 12 volt system for now because another LiFePO4 will be very expensive for me. I paid $895 for the LiFePO4, but that was because they charged me $182 dollars to ship to Puerto Rico and $73 in Taxes for my Beloved Country.

I was wondering if I can use an HIT (Panasonic) 330 watt solar panel that is rated at about 59 volts and about 5 amps to keep the battery charged?

https://cdn.shopify.com/s/files/1/0079/6003/5417/files/PanasonicHIT_335_340.pdf?v=1602800488

I know there are panels that are rated at around 12 volts but I figure if I go for the panels that have a higher voltage and current, then even when it is cloudy I will get enough volts and current to keep the battery charged. Please let me know if this can be a feasible option for my location. Thanx.

 

[snoobler]

Welcome to the forum.

You have 1280Wh of energy.

40A * 12V = 480W - this is the amount of power your 40A charge controller can provide to a 12V system (the unit likely publishes a slightly higher value for 12V system - use that).

With an MPPT controller, it gives you the flexibility to use higher voltage panels for lower voltage system, so the answer is "yes" to your use of an HIT 330W panel; however, you could safely use two of them to ensure you can produce peak power for longer.

More importantly than these details are what do you hope to accomplish with this system? With your existing capacity, you couldn't even run a typical residential refrigerator for 24 hours.

 

[NwCali]

solar panels versus hurricane, wonder which one will win? Maybe best to have it where you can temporarily take it down at times?

 

[frankie57pr]

Welcome to the forum.

You have 1280Wh of energy.

40A * 12V = 480W - this is the amount of power your 40A charge controller can provide to a 12V system (the unit likely publishes a slightly higher value for 12V system - use that).

With an MPPT controller, it gives you the flexibility to use higher voltage panels for lower voltage system, so the answer is "yes" to your use of an HIT 330W panel; however, you could safely use two of them to ensure you can produce peak power for longer.

More importantly than these details are what do you hope to accomplish with this system? With your existing capacity, you couldn't even run a typical residential refrigerator for 24 hours.

Thanx for the info. I don't need to power the refrigerator for too long, but if I did, what would you recommend?

 

[snoobler]

Thanx for the info. I don't need to power the refrigerator for too long, but if I did, what would you recommend?

A second battery for 24V and at least 1000W solar.

 

[frankie57pr]

A second battery for 24V and at least 1000W solar.

Thanx. That was what I was afraid of. I used up the $1400 Stimulus on what I got so far, so hopefully there will be another Stimulus in the future so I can get enough for that second Battery and solar panel in the near future.

 

[Hedges]

Typical modern full-size refrigerator is rated to consume 1500 Wh/day according to the consumer energy label.
My old ones consume more, and some small or more efficient models much less.
Search for your model number and see what consumption is estimated (given as kWh/year).
With that, you'll know what power is needed.

https://www.aimscorp.net/1500-Watt-Pure-Sine-Inverter.html

"No Load Consumption 0.8A"
That's about 10W, so 240 Wh/day if left on 24 hours/day. That would be about 16% overhead for a full-size refrigerator, or maybe 100% for some efficient refrigerators.
You can reduce that extra loss by shutting off inverter when sun goes down, back on in the morning.

"Efficiency 90%"
1500 Wh/day / 90% = 1670W drawn from battery.

If you have a full size refrigerator, you'll need about 2000 Wh/day for inverter + refrigerator.
If you have good sun exposure, you might get 5+ hours effective sun in the summer (so 400W PTC, 450W STC rated PV panel sufficient).
In winter, maybe 2 hours, so 1000W, 1250W STC rated panels. But maybe refrigerator doesn't run as much in cool weather.

Two of those 330W panels could be used on the 40A, 500W charge controller if one is aimed at morning sun, the other at afternoon.
I think that could meet summer refrigerator consumption, even full size. For winter, more panels and charge controller might be needed for a full size fridge, maybe not for a smaller one.

"100 AH LiFePO4 12 volt battery"

12V 100Ah LiFePO4 - EP12100

Nominal Voltage: 12.8v Charging Voltage: 14.4±0.2v Rated Capacity : 100Ah (0.2C, 25°C) Terminal Type: F12/M8 Dimensions (L x W x H): 13 x 6.6 x 8.4 (H + Terminal: 9) Inch Weight: 27lbs

www.expertpower.us

maximum charge current 50A.
You could have ordered a 50A charge controller, but since you ordered 40A, don't want to add a second 40A.

How cool does your weather get? What is record cold temperature? I think it stays reasonably warm (Puerto Rico, not Texas!) but max charge rate of LiFePO4 is reduced when cold.

 

[frankie57pr]

Typical modern full-size refrigerator is rated to consume 1500 Wh/day according to the consumer energy label.
My old ones consume more, and some small or more efficient models much less.
Search for your model number and see what consumption is estimated (given as kWh/year).
With that, you'll know what power is needed.

https://www.aimscorp.net/1500-Watt-Pure-Sine-Inverter.html

"No Load Consumption 0.8A"
That's about 10W, so 240 Wh/day if left on 24 hours/day. That would be about 16% overhead for a full-size refrigerator, or maybe 100% for some efficient refrigerators.
You can reduce that extra loss by shutting off inverter when sun goes down, back on in the morning.

"Efficiency 90%"
1500 Wh/day / 90% = 1670W drawn from battery.

If you have a full size refrigerator, you'll need about 2000 Wh/day for inverter + refrigerator.
If you have good sun exposure, you might get 5+ hours effective sun in the summer (so 400W PTC, 450W STC rated PV panel sufficient).
In winter, maybe 2 hours, so 1000W, 1250W STC rated panels. But maybe refrigerator doesn't run as much in cool weather.

Two of those 330W panels could be used on the 40A, 500W charge controller if one is aimed at morning sun, the other at afternoon.
I think that could meet summer refrigerator consumption, even full size. For winter, more panels and charge controller might be needed for a full size fridge, maybe not for a smaller one.

"100 AH LiFePO4 12 volt battery"

12V 100Ah LiFePO4 - EP12100

Nominal Voltage: 12.8v Charging Voltage: 14.4±0.2v Rated Capacity : 100Ah (0.2C, 25°C) Terminal Type: F12/M8 Dimensions (L x W x H): 13 x 6.6 x 8.4 (H + Terminal: 9) Inch Weight: 27lbs

www.expertpower.us

maximum charge current 50A.
You could have ordered a 50A charge controller, but since you ordered 40A, don't want to add a second 40A.

How cool does your weather get? What is record cold temperature? I think it stays reasonably warm (Puerto Rico, not Texas!) but max charge rate of LiFePO4 is reduced when cold.

My fridge is new and it is a kenmore 111.61215613. I couldn't find the energy label data on their website but my Kill a Watt device says it consumes 7.5 KW per Hr. It doesn't get cold here so low temps not a problem.

 

[Q-Dog]

My fridge has been running full time off of my battery backup since January 20. Here are my observations so far.

My refrigerator is about 10 years old and was one of the most efficient conventional refrigerators I could find when I bought it. (Samsung bottom freezer with single fridge door on top, no water/ice in the door) It uses about 1.2kWh per day in conditioned space ... a little more during spring and fall higher humidity when we open windows instead of running the A/C.

I have 4 times the battery capacity you have (24 volt, 200 ah) and with inverter losses the fridge can run about 30 hours on my battery backup. With 600 watts of solar it now runs the fridge full time, and doesn't charge from the grid (or generator) unless I get more than 2 days of heavy clouds/rain.

I ordered more battery cells, so In a week or 2 I should double my battery capacity so I can put my computer network and phone stuff on the backup full time. Will eventually add more panels. My math says 2000 watts should enough.

 

[Hedges]

My fridge is new and it is a kenmore 111.61215613. I couldn't find the energy label data on their website but my Kill a Watt device says it consumes 7.5 KW per Hr. It doesn't get cold here so low temps not a problem.

I couldn't find that model number either.
Here's one random Kenmore top freezer:

Kenmore 79432 23.8 cu. ft. 33" Top-Freezer Refrigerator w/ Internal Water Dispenser - White | Kenmore

Kenmore 79432 23.8 cu. ft. Top-Freezer Refrigerator - Balanced Refrigeration, Ample Storage The Kenmore 79432 23.8 cu...

www.kenmore.com

https://i.sears.com/s/d/pdf/mp-tc/10099713/prod_17720514012

"574 kWh/year"
574 kWh/year / 365 days/year = 1.57 kWh/day

Don't know what you meant by "7.5 KW per Hr", 7.5 kW is far to high for instantaneous consumption. If that was 7.5W average, then only 180 Wh per day; only a few highly efficient refrigerators might reach that.

Whatever the Kill a Watt says for kWh per day should let you determine how much PV system is required.

 

[frankie57pr]

Thanx Hedges. I did read it wrong. I just checked again to make sure and it says 0.72 KWH.

What I will be doing for now is running the fridge for just a few hrs during the day and a few at night when I run the generator. This will be until I can scrape up the $$$ for another 12 volt LiFePO4. I am still waiting for the charge controller and solar panels from Amazon. I might be requesting a refund soon because they failed to deliver. I ordered them back in early June.

Can u guys recommend a place for me to get the EP ever 40A charge controller and some good solar panels at a reasonably good price? Thanx.

 

[Hedges]

Batteries are the most expensive part, and additional capacity is relatively unnecessary.
One 12V 100 Ah battery is 1200 Wh. You would only use 720/1200 = 60% of its capacity in a 24 hour period without sun. Overnight, just 30%, so I think your single battery is ideal for a small system. (larger system, two for 24V as Snoobler says, but you can get by with 12V up to about 2000W inverter.)

Night time, with bottles of water in the freezer, should stay cold even if you turn inverter off. Or brine, concentration tuned to melt at a colder temperature good to keep frozen foods frozen. H2O and NaCl are cheaper than Li.

Charge controller, if you can cancel 40A model and get 50A that's better (assuming your battery says 50A max charge rate.)
Epever isn't the best (some people report at least some models hanging, needing to be reset) but is cheaper than some brands.

I would suggest a 50A charge controller for about 600W charging, and ideally 1000W to 1200W of PV panels. Shop total price including shipping; it is possible smaller panels will ship cheaper by common carrier. We get large panels strapped to a pallet by truck.
To deliver 600W takes about 700W (STC) of PV panels, because STC (standard test conditions) are 25 degree C laboratory conditions and power under field conditions are usually less.
Boosting PV array size 50% to about 1050W, with half the panels aimed at morning sun and half at afternoon sun, could deliver the same 600W but for more hours.

That would be likely to provide at least 1 kWh/day even in winter, enough for inverter continuous draw and the refrigerator. Summer, it'll make additional power during the day for fans, etc. Of course if multiple overcast days you might need the generator.

 

[frankie57pr]

Thanx Again Hedges. I'm glad I decided to register here. You guys are very helpful.

Yes, the max charge on my ExpertPower LiFePO4 is 50A. Can you recommend a good 50A charger?

 

[Hedges]

Looks like general rates in Puerto Rico are about $0.05/kWh (discounted for low income)

https://aeepr.com/es-pr/QuienesSomos/Ley57/Facturaci%C3%B3n/Tariff%20Book%20-%20Electric%20Service%20Rates%20and%20Riders%20Revised%20by%20Order%2005172019%20Approved%20by%20Order%2005282019.pdf

75% of power generation comes from petroleum, all imported.

U.S. Energy Information Administration - EIA - Independent Statistics and Analysis

www.eia.gov

With subsidies like that, easy to become dependent. Only unreliability can push you to alternative energy.

 

[Hedges]

Thanx Again Hedges. I'm glad I decided to register here. You guys are very helpful.

Yes, the max charge on my ExpertPower LiFePO4 is 50A. Can you recommend a good 50A charger?

I'm not sure, because my system is AC coupled (grid tie inverters) from SMA.

SanTan is one source with Epever, Victron, others. Victron is good but not cheap.

Charge Controllers | SanTan Solar

store.santansolar.com

Alt Energy Store also has several. Including Midnight which is popular, but higher amperage and expensive.

MPPT Charge Controller | MPPT Solar Charge Controller | altE

Shop MPPT solar charge controllers from Outback, Blue Sky Energy, Phocos, Xantrex and Morningstar. Have questions? Call 877-878-4060 today!

www.altestore.com

It may be Epever is the right price and wattage for your system.
Google the models you consider, and search this forum, see what you can learn.

Make sure the maximum PV voltage of the SCC is compatible with Voc of the PV panels. A few brands are only compatible with low voltage PV panels (often meant for recreational use.)

 

[frankie57pr]

Looks like general rates in Puerto Rico are about $0.05/kWh (discounted for low income)

https://aeepr.com/es-pr/QuienesSomos/Ley57/Facturaci%C3%B3n/Tariff%20Book%20-%20Electric%20Service%20Rates%20and%20Riders%20Revised%20by%20Order%2005172019%20Approved%20by%20Order%2005282019.pdf

75% of power generation comes from petroleum, all imported.

U.S. Energy Information Administration - EIA - Independent Statistics and Analysis

www.eia.gov

With subsidies like that, easy to become dependent. Only unreliability can push you to alternative energy.

That's true, Hedges, but ever since Hurricane Maria hit, our Power Grid hasn't been the same. Many outages lasting days and for some, weeks or more.

They just switched to a private company called LUMA and there have been protests and sabotage throughout the Island. Luma is now in the process of repairing and upgrading the power grid, so they said to expect many outages until the repairs are complete. No telling how long this process will take, so I want to be prepared.

 

[frankie57pr]

I'm not sure, because my system is AC coupled (grid tie inverters) from SMA.

SanTan is one source with Epever, Victron, others. Victron is good but not cheap.

Charge Controllers | SanTan Solar

store.santansolar.com

Alt Energy Store also has several. Including Midnight which is popular, but higher amperage and expensive.

MPPT Charge Controller | MPPT Solar Charge Controller | altE

Shop MPPT solar charge controllers from Outback, Blue Sky Energy, Phocos, Xantrex and Morningstar. Have questions? Call 877-878-4060 today!

www.altestore.com

It may be Epever is the right price and wattage for your system.
Google the models you consider, and search this forum, see what you can learn.

Make sure the maximum PV voltage of the SCC is compatible with Voc of the PV panels. A few brands are only compatible with low voltage PV panels (often meant for recreational use.)

The Victron 100V 50A looks OK. I would have to arrange the panels to meet the 100V max input but that is something I can figure out.

 

[macheung]

If you are PR, the difference between summer and winter sun intensity would be much less then most other parts or US and Canada, it would be practically summer all year long compared to say Toronto Canada.

 

[Vitamaltz]

Looks like general rates in Puerto Rico are about $0.05/kWh (discounted for low income)

https://aeepr.com/es-pr/QuienesSomos/Ley57/Facturaci%C3%B3n/Tariff%20Book%20-%20Electric%20Service%20Rates%20and%20Riders%20Revised%20by%20Order%2005172019%20Approved%20by%20Order%2005282019.pdf

75% of power generation comes from petroleum, all imported.

U.S. Energy Information Administration - EIA - Independent Statistics and Analysis

www.eia.gov

With subsidies like that, easy to become dependent. Only unreliability can push you to alternative energy.

I'm late to this thread but I live in PR too. Our kWh-dependent utility rate is actually about $0.20/kWh. I did solar financial estimates for years and quickly realized you really need to see a bill and do a little math to make sure you are including all riders and kWh-dependent taxes. It's always more than the published rate by the utility.

BTW, in my part of Puerto Rico the record low is 64 degrees, though I experienced a night in the mountains of Adjuntas that probably got into the 50s and w/ a 20-knot breeze ?