Newbie off grid system help

moonshine82 · January 2021

Hi just starting a new off grid solar system and need some recommend products currently I have 8 310 mono panels looking to purchase the right mppt controller and the correct inverter prob going to go with 4 lifepo4 batteries would love some recommends don’t want to drain or under utilize my panels

Photowhit · January 2021

What will your system voltage be?
Where are you located?
Do you know your daily loads?
Do you have certain expectations? Is the grid available?

BB. · January 2021

Also, while LiFePO4 batteries are just about the ideal battery (long life, store at any reasonable state of charge, no maintenance, light weight, compact, etc.)... They do have a few weak spots (one of which they are not cheap).

They do not like being over/under charged and do not like running much below 40F--And should not be operated below 32F--And many Lid Ion batteries have or are operated with a Battery Management System (BMS) to ensure that the individual cells are within voltage/temperature/current specifications, and can have an emergency disconnect if the operations will damage the cells. As always check the battery mfg specifications for details.

And--When picking equipment--There are some battery BMS that will integrate/talk with Charge Controllers and AC Inverters so that they will help the Li Ion batteries operate within their specifications.

Do not purchase anything until you have a good understanding of your loads, environmental requirements, and how all of the equipment will play together.

-Bill

706jim · January 2021

Probably the most significant is your location. FLA batteries do great in the cold so long as they are charged. I'd hate to buy Lithium ion batteries at great expense only to find that they won't work in your climate.

mike95490 · January 2021

With the low price of panels, you want to over panel a bit, and calculate ACTUAL expected harvest vs STC spec. And there will be days you don't have perfect sun and loose power.

moonshine82 · January 2021

I won’t be below 40f I’m on the NorCal coast, grid is not available need to know what mppt To get I’ll be getting lifepo4 batts just need to know wht charge controller and inverter to get that will work for these panels will be doing a 24v config

Photowhit · January 2021

moonshine82 said:

I won’t be below 40f I’m on the NorCal coast, grid is not available need to know what mppt To get I’ll be getting lifepo4 batts just need to know what charge controller and inverter to get that will work for these panels will be doing a 24v config

I won't say if your system will meet your needs, because you haven't discussed loads. But I would think a single Midnite Classic 150 would meet your needs. You can run your figures through the Midnite sizing tool to see if it will work. I suspect the configuration of 4 strings of 2 panels in parallel. I suggest you think abut the idea, and keep an eye open, for another panel of the same size and output. Most people find they grow into a 48 volt system over time. This configuration will basically completely max out the realistic output of the Midnite Classic 150. So it meets your;

moonshine82 said:

don’t want to drain or under utilize my panels

Here's a link to Midnite's string sizing tool;

MidNite Solar - Classic Sizing Tool.

moonshine82 · January 2021

Was thinking about one of these

moonshine82 · January 2021

Anyone have recommend in a correct inverter?

Photowhit · January 2021

Victron 250/85 doesn't list any certifications. California is a highly regulated state, check to see if yu need UL1741 equipment.

Photowhit · January 2021

moonshine82 said:
Anyone have recommend in a correct inverter?

I like Exeltech's XP600, but of course WE DON'T KNOOW WHAT YOUR LOADS ARE!!! So how could we possibly source a inverter?

moonshine82 · January 2021

Still need to get the specs on my Appliances etc and do the actual math on my loads... but for a ball park I’ll be running a chest freezer, 24 cu ft fridge, Edison and led lighting on a 2 bdrm cabin , washer and dryer (heating elements are propane ) 2 lg TVs some phone charging and laptop charging

mike95490 · January 2021

moonshine82 said:

Still need to get the specs on my Appliances etc and do the actual math on my loads... but for a ball park I’ll be running a chest freezer, 24 cu ft fridge, Edison and led lighting on a 2 bdrm cabin , washer and dryer (heating elements are propane ) 2 lg TVs some phone charging and laptop charging

Several motors there, it's a certainty that one will be running, and another will start up. To me, that calls for 48V 4000w inverter to handle that sort of surge. As for battery bank amp hours - that depends on what loads you want to shift. Easy to do laundry on a sunny day, just remember to start the last load of wash in time to complete the dry before the panels loose sun. But, if you don't want to load shift, you will pay with battery and solar 2x the size. 400ah at 48V is the basic battery that would work for the load shift scenario. PV array depends on your solar harvest hours and angle.

littleharbor2 · January 2021

If you're going with a Victron CC you should consider a Victron inverter.

jakobw · January 2021

Photowhit said:

Victron 250/85 doesn't list any certifications. California is a highly regulated state, check to see if yu need UL1741 equipment.

https://www.victronenergy.com/upload/documents/Certificate-UL-1741-and-CSA-C22.2-SmartSolar-MPPTs-150-45-up-to-250-100.pdf

jakobw · January 2021

littleharbor2 said:

If you're going with a Victron CC you should consider a Victron inverter.

I second this. Staying completely in Victron's system has some great advantages including complete system monitoring. They also have CAN Bus Lithium BMS support which you won't find with the Classics 150/200/250 or most of the US based brands right now that I have seen. Midnite does have a new controller out as was mentioned in one of the other threads recently. Looks like they have BMS support possibly but it's still in testing.

You may want to consider one of the 24V 3kVa Victron inverter models. You may need 2 depending on your loads and if you want split-phase 120/240 via 2x inverters or an autotransformer.

https://www.victronenergy.com/upload/documents/Datasheet-Multiplus-inverter-charger_2kVA-and-3kVA-120V-US-EN.pdf

If you don't want to go the charge controller route, you could always use a GT inverter combined with a Victron battery inverter. In that case, you'll get away with higher voltage strings and less wiring. Several other advantages as well.

Photowhit · January 2021

jakobw said:

Photowhit said:

Victron 250/85 doesn't list any certifications. California is a highly regulated state, check to see if yu need UL1741 equipment.

https://www.victronenergy.com/upload/documents/Certificate-UL-1741-and-CSA-C22.2-SmartSolar-MPPTs-150-45-up-to-250-100.pdf

Cool!

I was not trying to mislead anybody, I went to their spec sheet and it's void of any certifications.

jakobw · January 2021

Photowhit said:

jakobw said:

Photowhit said:

Victron 250/85 doesn't list any certifications. California is a highly regulated state, check to see if yu need UL1741 equipment.

https://www.victronenergy.com/upload/documents/Certificate-UL-1741-and-CSA-C22.2-SmartSolar-MPPTs-150-45-up-to-250-100.pdf

Cool!

I was not trying to mislead anybody, I went to their spec sheet and it's void of any certifications.

Sure, no worries at all. I just happen to be looking for them recently so I knew exactly where they were.

icarus · January 2021

moonshine82 said:

Still need to get the specs on my Appliances etc and do the actual math on my loads... but for a ball park I’ll be running a chest freezer, 24 cu ft fridge, Edison and led lighting on a 2 bdrm cabin , washer and dryer (heating elements are propane ) 2 lg TVs some phone charging and laptop charging

Sounds like a fair bit of loads, perhaps 5-8 kWh/day (WAG). Fridge alone, even with a goo modern inverter compressor fridge is likely to be ~1.5, freezer similar, W/D might average 1 per dat, TVs might be a couple . Phone is pretty small, but lap top might be 500wh/day.

It is absolutely critical that you define the load and their duration to get an accurate daily load estimate...then ad 30-50% for head room. Are tiny cabin, with propane fridge, no tv, no WD, only LED lighting, small water pump, we use ~500-1000 kWh/day day in and day out.

If you don’t do that you will be doomed to make an expensive mistake. All calcs should be derived from the loading.

Tony

Newbie off grid system help

Comments

Categories