diy solar

diy solar

Powering a Mint Split unit in an RV by solar and lithium batteries

That was for the whole rig. Reused existing cabling saved time and money. Inserted (with breaker) 48V to 12V converter to handle 12V loads.
Just built out new rig with 24V system (544AH) with single 3k Multiplus and a wall mount mini split. kept propane for cooking and wave6 heater this time.. 1480W on the roof
On that 24V battery bank... Is that 544Ah at 24V, which would be larger than 200Ah at 48V?
Or is perhaps a pair of 12V batteries in series, each providing 272Ah?... Or basically: Is it really 272Ah at 24V?
 
Hookem,,
I used Lishen 272AH cells. 8 cells in 2 packs. so the battery bank is 544AH at 24V. It is larger than my old 48V because I wanted to have the reserve for several days of cloudy weather or being parked under trees.
 
Hookem,,
I used Lishen 272AH cells. 8 cells in 2 packs. so the battery bank is 544AH at 24V. It is larger than my old 48V because I wanted to have the reserve for several days of cloudy weather or being parked under trees.
OK, thanks for the clarification.
BTW, I also noticed that you lowered your Solar from 1800W to 1480W... How's that working out?
Are you able to keep the Mini-Spilt running 24/7?... Is 1480W of Solar enough to recharge the (544Ah @ 24V) battery bank?
 
OK, thanks for the clarification.
BTW, I also noticed that you lowered your Solar from 1800W to 1480W... How's that working out?
Are you able to keep the Mini-Spilt running 24/7?... Is 1480W of Solar enough to recharge the (544Ah @ 24V) battery bank?
We do try to chase 75-85 temps. We actually prefer open windows and fresh air... we do run the air during the day for the pets...nice to not have to worry about them when we are out running around in hot weather. We do not typically run the ac overnight. The closest we have come to that was when we had to run it to about 8:30 PM then we opened the windows... the lowest we got down to was about 71% SOC. We were back at 100% by 2PM with air running the next day. (good solar sky) Once the rig is cooled down (key is to start before the heat builds up) the mini only draws about 450-480W (AC).
I lowered to 1480 because of roof space and the new rig only has 11.5 cu ft residential fridge, water pump, lights, 2 laptops, and 2 dc TVs. We use the water heater in electric only once a day but it is propane as well. Cooking and heat are propane now. Old rig: 21ft fridge, induction cooktop, convection oven, electric only water heater, 42 inch big screen plus the rest.. no propane at all. The Dutch Star was 40ft with 4 slides (air leaks). The new travel trailer is 27ft one and a half slide.
In the new rig we had 3 stormy days in Flagstaff and stayed in the mid fifties SOC without changing our routine. (other than watching a couple movies with popcorn). If we run into trouble we do carry a Westinghouse IPro 2500 genny as a backup.
 
OK, thanks for the clarification.
BTW, I also noticed that you lowered your Solar from 1800W to 1480W... How's that working out?
Are you able to keep the Mini-Spilt running 24/7?... Is 1480W of Solar enough to recharge the (544Ah @ 24V) battery bank?
key is an energy audit... with our expected usage.. it was projected to keeps us going for at least 3 days. turns out I over estimated our usage
 
key is an energy audit... with our expected usage.. it was projected to keeps us going for at least 3 days. turns out I over estimated our usage
Based on this video (link), I'm considering running a 9K Btu Mini-split (24/7, if possible) on a Sprinter-based Class C rig: Winnebago Navion.
So far my plans are 1600W of Solar (4*400W panels) and 750Ah of LiFePO4 batteries at 12V, adding 4 * 125Ah to the factory installed 2* 125Ah.

I'd remove the roof-top A/C to make room for Solar panels, with the Mini-Split outer unit installed above the rear bumper.
BTW, I'm considering Cassette inner unit, so the Mini-split would require a 230V Inverter since I've not found a 120V unit.

 
Based on this video (link), I'm considering running a 9K Btu Mini-split (24/7, if possible) on a Sprinter-based Class C rig: Winnebago Navion.
So far my plans are 1600W of Solar (4*400W panels) and 750Ah of LiFePO4 batteries at 12V, adding 4 * 125Ah to the factory installed 2* 125Ah.

I'd remove the roof-top A/C to make room for Solar panels, with the Mini-Split outer unit installed above the rear bumper.
BTW, I'm considering Cassette inner unit, so the Mini-split would require a 230V Inverter since I've not found a 120V unit.

That sounds like you will have a sweet setup when you are done. I had a cassette in the Dutch Star only because I did not have any wall space inside the RV. I like the wall unit we now have (more efficient to convert dc to 120V AC) because it keeps the install simpler (1 Inverter no sub panels) and cheaper. With my cassette I had a fabricator make me a tri fold aluminum box with a flange to go through the roof and hung the cassette unit inside of it. More sealing to check on the roof and takes space. The wall unit only has one hole to check and does not take any roof space. (more panels) It also has the added benefit of reusing the breaker from the old ac unit in the distribution panel. anytime I can shorten the roof I will take it.
 
I'm with you on the added complexity of the Cassete unit... But it's a real "clean" look!
To be honest, with the Cassette plan I'm thinking of tackling the Electrical, and deferring the Mini-Split/Cassette to an HVAC expert.
(I watched another video on FB where the Outer unit was painted to match the Coach... real cool looking... pun intended!)

Anyway, at this point, I'm just brainstorming ideas, so I appreciate all of the feedback... My main concerns are around the power budget:
1) Is 750Ah of LiFePO4 battery enough to let the A/C unit run 24/7?
I presume it would have a better chance at keeping the rig cool, drawing the minimum amount of energy if it's always running!
2) Is ~1600W of Solar enough to recharge that battery bank? (A 30A Diesel Gen could come to the rescue on real cloudy days).
With the roof-top A/C removed I think I could fit 4 panels no larger than 80"x40" each (the roof-top is about 81" wide).
There are few 400W+ options that may work, for example, TrinaSolar, Canadian Solar, and LG ($$, ouch!).



 
I'm with you on the added complexity of the Cassete unit... But it's a real "clean" look!
To be honest, with the Cassette plan I'm thinking of tackling the Electrical, and deferring the Mini-Split/Cassette to an HVAC expert.
(I watched another video on FB where the Outer unit was painted to match the Coach... real cool looking... pun intended!)

Anyway, at this point, I'm just brainstorming ideas, so I appreciate all of the feedback... My main concerns are around the power budget:
1) Is 750Ah of LiFePO4 battery enough to let the A/C unit run 24/7?
I presume it would have a better chance at keeping the rig cool, drawing the minimum amount of energy if it's always running!
2) Is ~1600W of Solar enough to recharge that battery bank? (A 30A Diesel Gen could come to the rescue on real cloudy days).
With the roof-top A/C removed I think I could fit 4 panels no larger than 80"x40" each (the roof-top is about 81" wide).
There are few 400W+ options that may work, for example, TrinaSolar, Canadian Solar, and LG ($$, ouch!).



sorry for the delay today was a travel day. There are so many variables to the question... how well insulated is the rig, air leakage, how hot is it outside, where the rig is located.... are the temps at night comfortable enough to open windows. I know that on both rigs I over built the system...but hey better more than not enough.. If you are comfortable with starting at 1600W solar and have the roof space.. than why not. If you are going to do a DIY lifo4 pack than get it as big as you have the space for in the rig and the checkbook. (it would be wise to get 1 or 2 spare cells..trust me) If you are planning on going the drop in route...start reasonable and plan for expansion if needed. Just make sure the batteries you buy can be placed in parallel..some do not support that. You can find people on the forum that have experience with the drop ins for detailed reviews... SOK, Ampere Time, and Battle Born I see mentioned a lot here. SanTan Solar has some used panels that are very well priced... more panels needed but priced right. I put 2 of the 250W T series on a friend's Class C in 2020... still no issues for her. 500W for $100. Will Prowse just mentioned another vender that has decent prices but only sells by the pallet. If you run out of roof space.. consider stacking the panels on pull out drawer slides... for example: 4 panels with 4 more on drawer slides underneath. When you get to you destination you can pull out the lower ones manually or via an actuator.... bonus they can provide shade as well.
 
I'm with you on the added complexity of the Cassete unit... But it's a real "clean" look!
To be honest, with the Cassette plan I'm thinking of tackling the Electrical, and deferring the Mini-Split/Cassette to an HVAC expert.
(I watched another video on FB where the Outer unit was painted to match the Coach... real cool looking... pun intended!)

Anyway, at this point, I'm just brainstorming ideas, so I appreciate all of the feedback... My main concerns are around the power budget:
1) Is 750Ah of LiFePO4 battery enough to let the A/C unit run 24/7?
I presume it would have a better chance at keeping the rig cool, drawing the minimum amount of energy if it's always running!
2) Is ~1600W of Solar enough to recharge that battery bank? (A 30A Diesel Gen could come to the rescue on real cloudy days).
With the roof-top A/C removed I think I could fit 4 panels no larger than 80"x40" each (the roof-top is about 81" wide).
There are few 400W+ options that may work, for example, TrinaSolar, Canadian Solar, and LG ($$, ouch!).



BTW.... remember to keep receipts for eveything... bolts, panels, wire, framing, tools... you get some back when you file taxes.... Your rig has a bedroom, kitchen and bathroom...qualifies just like a house. I got 30% back on the first rig and I think 26% back on the current rig on fed... nothing on the state.
 
sorry for the delay today was a travel day. There are so many variables to the question... how well insulated is the rig, air leakage, how hot is it outside, where the rig is located.... are the temps at night comfortable enough to open windows. I know that on both rigs I over built the system...but hey better more than not enough.. If you are comfortable with starting at 1600W solar and have the roof space.. than why not. If you are going to do a DIY lifo4 pack than get it as big as you have the space for in the rig and the checkbook. (it would be wise to get 1 or 2 spare cells..trust me) If you are planning on going the drop in route...start reasonable and plan for expansion if needed. Just make sure the batteries you buy can be placed in parallel..some do not support that. You can find people on the forum that have experience with the drop ins for detailed reviews... SOK, Ampere Time, and Battle Born I see mentioned a lot here. SanTan Solar has some used panels that are very well priced... more panels needed but priced right. I put 2 of the 250W T series on a friend's Class C in 2020... still no issues for her. 500W for $100. Will Prowse just mentioned another vender that has decent prices but only sells by the pallet. If you run out of roof space.. consider stacking the panels on pull out drawer slides... for example: 4 panels with 4 more on drawer slides underneath. When you get to you destination you can pull out the lower ones manually or via an actuator.... bonus they can provide shade as well.
It seems like Solar is king! (the more the merrier.. to have a chance at recharging the batteries). Thanks!
 
BTW.... remember to keep receipts for eveything... bolts, panels, wire, framing, tools... you get some back when you file taxes.... Your rig has a bedroom, kitchen and bathroom...qualifies just like a house. I got 30% back on the first rig and I think 26% back on the current rig on fed... nothing on the state.
found the web site... signature solar...they also sell mini splits...they have a 9K with 38SEER...what?
 
BTW.... remember to keep receipts for eveything... bolts, panels, wire, framing, tools... you get some back when you file taxes.... Your rig has a bedroom, kitchen and bathroom...qualifies just like a house. I got 30% back on the first rig and I think 26% back on the current rig on fed... nothing on the state.
Will do. Thx.
 
OK, here are some numbers I've been crunching for a potential Mini-Split install on a Sprinter Class C motorhome (Winnebago Navion).
The inspiration is the YouTube video linked below, describing a 9K Btu install on a Class C motorhome of comparable size.

Mini-Split install, what would it take?

It seems to me ( thinking out loud) that the main questions to be answered are:
1) When the sun is *not* shining, can the battery bank sustain the overall power draw?
(Ideally, batteries could go to near near-depleted state without damage)
** The size of the battery bank could be derived from the answer to that question **

2) And when the sun is shining, can the solar panels fully recharge the battery bank, while sustaining the overall power draw?
(Worse-case: batteries start from a near-depleted state)
** The size of the solar array could be derived from the answer to that question **

Now, let's draw some speculative Off-grid scenarios for a typical Class C motorhome:
* Assuming an average consumption budget of 200Ah per day without A/C, that's about 100W per hour.
* According to this video (link), a 9K Btu mini-split running 24/7, on average consumes ~239W/Hour on cooler hours (night), and ~460W on warmer hours. So let's say that's 250W from 6 PM to 8 AM, and 500W from 8 AM to 6 PM.

Nighttime Analysis (6 PM to 8 AM, running on batteries):
Consumption = (250W/Hour, A/C) + (100W/Hour, Other) = 350W/Hour total
Battery Draw (Watts) = 350W/Hour * 14 Hours = 4900W.
Battery Draw (Amps) = 4900W/12V = 408A
So let's say that's 410A drain from the batteries, and if that load were to represent 80% of battery capacity, the battery bank must be at least 512Ah. (E.g., the video claims a 600Ah battery bank is sufficient)

Daytime Analysis (8 AM to 6 PM, running on Solar):
Consumption = (500/Hour, A/C) + (100W/Hour, Other) = 600W/Hour total
Let's say that during the 10-hour period, on average, we get 5 hours at full capacity, and 5 hours with enough Solar to cover the consumption budget (600W/Hour).

So during the 5 recharge hours, the required recharge power per hour would be 4900W/(5 Hours) = 980W/Hour.
Hence, the minimum Panel Capacity = Recharge + Consumption = 980W/Hour (Recharge) + 600W/Hour (Consumption) = 1580Watts/Hour.
Based on all the above, it seems like minimum power requirements are:
1) Battery Capacity = 600Ah+
2) Solar Capacity = 1600W+ (clearly, more would be best!)

*** DISCLAIMER ***
I have *not* done this (yet), so the points above are just my assumptions (and you know what they say about assumptions!)

009 - [Redo] Solar Mini Split Air Conditioner Runs 24/7/365 Day & Night
 
OK, here are some numbers I've been crunching for a potential Mini-Split install on a Sprinter Class C motorhome (Winnebago Navion).
The inspiration is the YouTube video linked below, describing a 9K Btu install on a Class C motorhome of comparable size.

Mini-Split install, what would it take?
It seems to me ( thinking out loud) that the main questions to be answered are:
1) When the sun is *not* shining, can the battery bank sustain the overall power draw?
(Ideally, batteries could go to near near-depleted state without damage)
** The size of the battery bank could be derived from the answer to that question **

2) And when the sun is shining, can the solar panels fully recharge the battery bank, while sustaining the overall power draw?
(Worse-case: batteries start from a near-depleted state)
** The size of the solar array could be derived from the answer to that question **

Now, let's draw some speculative Off-grid scenarios for a typical Class C motorhome:
* Assuming an average consumption budget of 200Ah per day without A/C, that's about 100W per hour.
* According to this video (link), a 9K Btu mini-split running 24/7, on average consumes ~239W/Hour on cooler hours (night), and ~460W on warmer hours. So let's say that's 250W from 6 PM to 8 AM, and 500W from 8 AM to 6 PM.

Nighttime Analysis (6 PM to 8 AM, running on batteries):
Consumption = (250W/Hour, A/C) + (100W/Hour, Other) = 350W/Hour total
Battery Draw (Watts) = 350W/Hour * 14 Hours = 4900W.
Battery Draw (Amps) = 4900W/12V = 408A
So let's say that's 410A drain from the batteries, and if that load were to represent 80% of battery capacity, the battery bank must be at least 512Ah. (E.g., the video claims a 600Ah battery bank is sufficient)

Daytime Analysis (8 AM to 6 PM, running on Solar):
Consumption = (500/Hour, A/C) + (100W/Hour, Other) = 600W/Hour total
Let's say that during the 10-hour period, on average, we get 5 hours at full capacity, and 5 hours with enough Solar to cover the consumption budget (600W/Hour).

So during the 5 recharge hours, the required recharge power per hour would be 4900W/(5 Hours) = 980W/Hour.
Hence, the minimum Panel Capacity = Recharge + Consumption = 980W/Hour (Recharge) + 600W/Hour (Consumption) = 1580Watts/Hour.
Based on all the above, it seems like minimum power requirements are:
1) Battery Capacity = 600Ah+
2) Solar Capacity = 1600W+ (clearly, more would be best!)

*** DISCLAIMER ***
I have *not* done this (yet), so the points above are just my assumptions (and you know what they say about assumptions!)

009 - [Redo] Solar Mini Split Air Conditioner Runs 24/7/365 Day & Night
AC to DC calculator
 
Hope I can insert a side question without sidetracking the thread ....

If I have an existing 110V inverter with sufficient power capability .... would there be any problem just using a transformer to power one of these high efficiency 208/230 mini splits?
 
OK, here are some numbers I've been crunching for a potential Mini-Split install on a Sprinter Class C motorhome (Winnebago Navion).
The inspiration is the YouTube video linked below, describing a 9K Btu install on a Class C motorhome of comparable size.

Mini-Split install, what would it take?
It seems to me ( thinking out loud) that the main questions to be answered are:
1) When the sun is *not* shining, can the battery bank sustain the overall power draw?
(Ideally, batteries could go to near near-depleted state without damage)
** The size of the battery bank could be derived from the answer to that question **

2) And when the sun is shining, can the solar panels fully recharge the battery bank, while sustaining the overall power draw?
(Worse-case: batteries start from a near-depleted state)
** The size of the solar array could be derived from the answer to that question **

Now, let's draw some speculative Off-grid scenarios for a typical Class C motorhome:
* Assuming an average consumption budget of 200Ah per day without A/C, that's about 100W per hour.
* According to this video (link), a 9K Btu mini-split running 24/7, on average consumes ~239W/Hour on cooler hours (night), and ~460W on warmer hours. So let's say that's 250W from 6 PM to 8 AM, and 500W from 8 AM to 6 PM.

Nighttime Analysis (6 PM to 8 AM, running on batteries):
Consumption = (250W/Hour, A/C) + (100W/Hour, Other) = 350W/Hour total
Battery Draw (Watts) = 350W/Hour * 14 Hours = 4900W.
Battery Draw (Amps) = 4900W/12V = 408A
So let's say that's 410A drain from the batteries, and if that load were to represent 80% of battery capacity, the battery bank must be at least 512Ah. (E.g., the video claims a 600Ah battery bank is sufficient)

Daytime Analysis (8 AM to 6 PM, running on Solar):
Consumption = (500/Hour, A/C) + (100W/Hour, Other) = 600W/Hour total
Let's say that during the 10-hour period, on average, we get 5 hours at full capacity, and 5 hours with enough Solar to cover the consumption budget (600W/Hour).

So during the 5 recharge hours, the required recharge power per hour would be 4900W/(5 Hours) = 980W/Hour.
Hence, the minimum Panel Capacity = Recharge + Consumption = 980W/Hour (Recharge) + 600W/Hour (Consumption) = 1580Watts/Hour.
Based on all the above, it seems like minimum power requirements are:
1) Battery Capacity = 600Ah+
2) Solar Capacity = 1600W+ (clearly, more would be best!)

*** DISCLAIMER ***
I have *not* done this (yet), so the points above are just my assumptions (and you know what they say about assumptions!)

009 - [Redo] Solar Mini Split Air Conditioner Runs 24/7/365 Day & Night
this load calculator is not 100% but it might get you there...
remember that inverters can be as low as 75% to 90% efficient...the more expensive the unit usually the better
 
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