New to solar - Looking to install 24v/MPP lv2424-3.5kw-2/270w panels

Mason · Jun 5, 2020

Proposed Solar System

MPP - pip-lv2424-msd-2400w-24v-80a-mppt-60a
24v LifePO4 Powerwall 3.5KW
Renogy 2Pcs 270 Watt 24 Volt Solar Panel 1080W - In series

I live in Northern AZ

Being new to solar is there something:
I am missing
Need to be concerned with this system
Mistake a virgin to solar should avoid

Reason for doing this. Wife's medical equipment that needs lots of power. And, can not survive without treatments.
If I get working I will plan on duplicating the system to run in parallel to make sure power is available.

Supervstech · Jun 5, 2020

Mason said:
Proposed Solar System

MPP - pip-lv2424-msd-2400w-24v-80a-mppt-60a
24v LifePO4 Powerwall 3.5KW
Renogy 2Pcs 270 Watt 24 Volt Solar Panel 1080W - In series

I live in Northern AZ

Being new to solar is there something:
I am missing
Need to be concerned with this system
Mistake a virgin to solar should avoid

Reason for doing this. Wife's medical equipment that needs lots of power. And, can not survive without treatments.
If I get working I will plan on duplicating the system to run in parallel to make sure power is available.

Ok, you need to separate KWh from KW...

CONSUMPTION and PRODUCTION devices are purchased in WATTS (or KiloWatts)

storage, and energy usage, is measured in Wh (KWh)

mixing them up makes math and understanding very difficult.

Your two 270W panels or is it 4 270 W panels? 1080W makes me think 4, but you said 2...

Your power wall is 24V, and 3.5 KWh (around 140Ah)

Mason · Jun 5, 2020

Thank you so much for your reply. Sorry for the poor communication. I let me apologize in advance if it miss communicated again.
Yes, the Battery provides 3.5kwh from bigbattery
Yes, I was planning on using only 2 - 270 watt 24 volt panels for total hourly production of >540 watts. Based on average of 7.8 hours of production time where we live an average of 3.5 KiloWatts of production.

The medical equipment needs are 3 KiloWatt per 24 hour period.

When I build the second system I was planning using an additional 2 - 270 watt panels again to mirror the first system. If we need to use 4 - 270 watt panels for each system to keep from damaging the Powerwall system that is doable. And, clearly will provide better production of power on poor weather days.

I do not know if running to little solar input would hurt the Powerwall system. And you are correct 4 panels would provide 1080 watts. But, I was thinking that 540 watt generation per system was all the generation we needed on each systems.

Between the two mirrored systems the medical needs would be met from a daily watt generation requirement with two days of battery reserve from down time from bad weather. We also have a generator that we could use to charge the batteries while supporting the medical equipment. The generator runs off of propane. We have a 500 gallon propane system.

madmax · Jun 5, 2020

Panel placement and other factors can make a huge difference in output. That aside, your basing your numbers on optimal numbers, and that will lead you down to a solution that may be underproducing what you need.
1. You assume your panels will produce 270-and that may be true initially, but panels do reduce output over time- and also when heated up.
2. 7.8 hrs- but is it 7.8 hrs of full power output? (that is not achievable where I am. maybe in AZ?)
3. You have 3.5kwh battery, and a rough total of 3.5kw of production, and a rough total of 3kw of usage, leaving you a possible 500w of excess (based upon the above). Your "non sun generating times" would roughly be 2kw and 1kw during sun generaton, roughly 66% power drain from the pack.

There isn't much wiggle room here at all. If you are talking about the BYD packs from Bigbattery, I hear there are capacity issues- and not everyone is getting 3.5. Not charging to 100% will also give you better battery life, and not excessively draining them will also give you better battery life.

I'd definately go the route of 4 panels. Consider this; extra solar power can directly power the load- thats requires roughly 2-300 watts continuous. in the early morning, more panels will produce more power early on- and thus reduce battery strain as the load can be prioritzed for the equipment. This also continues into the early evenings, before the system dips into stored power.

The single MPP is certainly capable of handling much more solar and much more battery. Id certainly consider getting another battery and adding it on- As it stands you do not have 2 days of reserves (3kwh of daily use, 3.5kwh of storage). Thats a day's worth. If you had a full charge going into the evening of day 1, and it is bad weather all day on day 2, you'd be dry within 8 hours.

The only good thing is that you can setup grid power to take over, and also charge up those batteries.

You can also just set it up so that this is more like a solar UPS- use solar when avaliable for the load, but never dig into the batteries for power unless the grid goes down. If thats the case, 2 panels may be sufficient, but one battery would give you 24hrs, unless your in perfect conditions.

Edit: forgot to say, your power wall (or battery) will not care- the solar MPPT charger within the unit will determine how to convert the solar into the proper charge profile for your battery.

madmax · Jun 5, 2020

Mason, without naming specifics, I can't think of too many devices that have a continuous 250-300W draw. Bipap/cpap type, but when you say treatments, I am thinking maybe you mean oxygen therapy, or a nebulizer. I believe those oxygen concentrators draw quite a bit more than 300, but its not continuous.

If its the first 2, you have other options which give you more flexibility- (DC powered cpap native 12v and dc nebulizers). If it is the oxygen concentrator, you would need to keep that running.

The other factor is of course, the other creature comforts- lights, fans, etc, and don't forget the Fridge. Don't know how rural you are, but Im going to assume that since you have a 500gal propane tank, you have no Natural gas. Your home may be either a electric water heater, or a propane one.

I've had some family with some medical issues- while its under control, I did do a setup at home in case of prolonged outtage in case they needed to be moved from their own home.

Supervstech · Jun 5, 2020

Mason said:
Thank you so much for your reply. Sorry for the poor communication. I let me apologize in advance if it miss communicated again.
Yes, the Battery provides 3.5kwh from bigbattery
Yes, I was planning on using only 2 - 270 watt 24 volt panels for total hourly production of >540 watts. Based on average of 7.8 hours of production time where we live an average of 3.5 KiloWatts of production.

The medical equipment needs are 3 KiloWatt per 24 hour period.

When I build the second system I was planning using an additional 2 - 270 watt panels again to mirror the first system. If we need to use 4 - 270 watt panels for each system to keep from damaging the Powerwall system that is doable. And, clearly will provide better production of power on poor weather days.

I do not know if running to little solar input would hurt the Powerwall system. And you are correct 4 panels would provide 1080 watts. But, I was thinking that 540 watt generation per system was all the generation we needed on each systems.

Between the two mirrored systems the medical needs would be met from a daily watt generation requirement with two days of battery reserve from down time from bad weather. We also have a generator that we could use to charge the batteries while supporting the medical equipment. The generator runs off of propane. We have a 500 gallon propane system.

7.8h production without sun tracking won’t produce 3.5KWh (remember, production and usage is KWH not kws!) you need to factor in poor sun angle loss. Unless you are tracking the sun.
And 3KWh per day is the same as 3KW per 24h...but could be interpreted as 3KW per hour each 24hour period, so can be confusing.

Mason · Jun 5, 2020

madmax said:
Panel placement and other factors can make a huge difference in output. That aside, your basing your numbers on optimal numbers, and that will lead you down to a solution that may be underproducing what you need.
1. You assume your panels will produce 270-and that may be true initially, but panels do reduce output over time- and also when heated up.
2. 7.8 hrs- but is it 7.8 hrs of full power output? (that is not achievable where I am. maybe in AZ?)
3. You have 3.5kwh battery, and a rough total of 3.5kw of production, and a rough total of 3kw of usage, leaving you a possible 500w of excess (based upon the above). Your "non sun generating times" would roughly be 2kw and 1kw during sun generaton, roughly 66% power drain from the pack.

There isn't much wiggle room here at all. If you are talking about the BYD packs from Bigbattery, I hear there are capacity issues- and not everyone is getting 3.5. Not charging to 100% will also give you better battery life, and not excessively draining them will also give you better battery life.

I'd definately go the route of 4 panels. Consider this; extra solar power can directly power the load- thats requires roughly 2-300 watts continuous. in the early morning, more panels will produce more power early on- and thus reduce battery strain as the load can be prioritzed for the equipment. This also continues into the early evenings, before the system dips into stored power.

The single MPP is certainly capable of handling much more solar and much more battery. Id certainly consider getting another battery and adding it on- As it stands you do not have 2 days of reserves (3kwh of daily use, 3.5kwh of storage). Thats a day's worth. If you had a full charge going into the evening of day 1, and it is bad weather all day on day 2, you'd be dry within 8 hours.

The only good thing is that you can setup grid power to take over, and also charge up those batteries.

You can also just set it up so that this is more like a solar UPS- use solar when avaliable for the load, but never dig into the batteries for power unless the grid goes down. If thats the case, 2 panels may be sufficient, but one battery would give you 24hrs, unless your in perfect conditions.

Edit: forgot to say, your power wall (or battery) will not care- the solar MPPT charger within the unit will determine how to convert the solar into the proper charge profile for your battery.

Thank you for your insights. We were thinking if we create two mirrored systems each system would consist of one battery, one solar panel array (as recommended 4 - 570 watt 24 panels), and one Powerwall system. The thinking is if one system had a component failure such as the Powerwall unit we could move PV and battery to the other Powerwall system. If one of the mirrored systems had a catastrophic failure the other system being totally separated would limit complete failure.

I was surprised to find out that in the Prescott area of Northern Arizona that 7.8 was the peak production period. I have been calculating solar power production on 250 Watt from every panel rated at 270 and peak production period to be only 7 not 7.8. We we live their will be no shade on the panels any time of the day. But as suggested having 4 panels will provide a higher confidence in production capacity.

Thank you for your thoughts on battery capacity. After will commented about the lower capacity he experienced. We saw bigbattery reduce the expected capacity to be 3.5 kwh. We thought if the battery we get provides less than 3.5 kwh we would get a second battery to make sure we have the 3.5 kwh capacity for each of the mirrored systems. Thank you for highlighting the battery issue.

We were planning on connecting the medical equipment to each of the mirrored systems. That way each system can be monitored for performance and improved as necessary.

Mason · Jun 5, 2020

Supervstech said:
7.8h production without sun tracking won’t produce 3.5KWh (remember, production and usage is KWH not kws!) you need to factor in poor sun angle loss. Unless you are tracking the sun.
And 3KWh per day is the same as 3KW per 24h...but could be interpreted as 3KW per hour each 24hour period, so can be confusing.

Thank you for your insights. Other have suggested 4 panels to address the margin of error in my original plan which I believe will address the lack of tracking among other product margin of errors to be properly considered.

Mason · Jun 5, 2020

madmax said:
Mason, without naming specifics, I can't think of too many devices that have a continuous 250-300W draw. Bipap/cpap type, but when you say treatments, I am thinking maybe you mean oxygen therapy, or a nebulizer. I believe those oxygen concentrators draw quite a bit more than 300, but its not continuous.

If its the first 2, you have other options which give you more flexibility- (DC powered cpap native 12v and dc nebulizers). If it is the oxygen concentrator, you would need to keep that running.

The other factor is of course, the other creature comforts- lights, fans, etc, and don't forget the Fridge. Don't know how rural you are, but Im going to assume that since you have a 500gal propane tank, you have no Natural gas. Your home may be either a electric water heater, or a propane one.

I've had some family with some medical issues- while its under control, I did do a setup at home in case of prolonged outtage in case they needed to be moved from their own home.

Thank you for your thoughts and insights.

The equipment is:
oxygen concentrator (bad days 24 hours a day) However, not often at a bad level (every sixty to 90 days). On bad days back up with grid power or in grid down situation propane generator to supplement. We also have oxygen tanks that will last several days. Normally one hour a day to produce Ozone.
Ozone generator (medical office grade device) Combined with the oxygen generator produce two types of therapy. Ozone generator consumes watts like a portable computer (operates 1 hour a day)
Rife Machine (Medical Office grade device). - Consumes watts like two refrigerators (operates 6 hours a day)
Quantum entanglement scalar wave generator - Consume watts like two refrigerators (operates 4 hours day)
Scalar wave generators - Consumes watts like a portable computer (operates 8 hours a day)
Also refrigerator, chest freezer, propane hot water and cooking, no natural gas.
Prescott has a very mild summer. We are at 5250 foot elevation. Doors open, maybe a fan a few times a year.
Winter and nights can be cold, so on a down situation it is Mr. Heater during the day. We are blanket kind of people at night.
We have LED lights in the house with 12VDC lights for back up of grid down.

The reason for two mirrored systems, each with 3.5kwh battery, Powerwall, and now 4 - 270 watt 24 volt panel arrays. In normal situation to handles the medical needs and in a grid down situation medical is st priority (nothing else matters - refrigerator food can be replaced). If one of the mirrored system has a 100% catastrophic failure (no panels or battery to redeployed) during a grid down situation supplement with propane generator for medical equipment support and fast charge the battery. We never let the propane level get below 60%.

Both system operating have the potential of producing 7kw each, and storing up to 7kwh total. Current treatment protocol is stagered throughout the day (matches what would be peak solar production period). So the big watt consumption would be during day and freezer and refrigerator, light would be the drain at night unless we were running the oxygen generator for a bad situation. Does any of this make sense?

madmax · Jun 6, 2020

Mostly, but you can parallel the systems making it actually higher availability even if one mpp unit goes down, you'd have access to 1 mpp unit, the 4 panels, and both batteries. All without lifting a finger.

As far as the other items go, I really have no clue, and are on the homeopathic/experimental spectrum of things...at least you know it's consumption. Some seem a bit higher than layed out previously, especially if you have multiple items running at the same time.

Mason · Jun 6, 2020

madmax said:
Mostly, but you can parallel the systems making it actually higher availability even if one mpp unit goes down, you'd have access to 1 mpp unit, the 4 panels, and both batteries. All without lifting a finger.

As far as the other items go, I really have no clue, and are on the homeopathic/experimental spectrum of things...at least you know it's consumption. Some seem a bit higher than layed out previously, especially if you have multiple items running at the same time.

Thank you for your comments. I am studying the manual at this moment. Allot to learn (at least for me) to successfully deploy a parallel configuration. My first attempt was two mirrored systems. Splitting the load across both systems. The treatments are not at the same time.

Since the doctors gave my wife a year to live (18 years ago). Telling her "go home a die, we have nothing for you" we had no choice but move to proven science (just not science accepted by the AMA/pharmaceutical industry). The technology we use is based on many principles demonstrated by Nicola Tesla, validated with evidenced based medical science in the 1930 and confirmed by hundreds of universities over the last 30 years. But, we agree, to the AMA/Pharm industry we are way outside the accepted norm. But, as Nicola Tesla commented:
'If you want to find the secrets of the universe, think in terms of energy, frequency and vibration.',
As I had to study physiology and non tradition medicine to move my wife from death bed to high quality of life.
My mission today to figure out and operate a solar system.

Words, cannot express our appreciation for your time and sharing your knowledge. Again, thank you.

madmax · Jun 6, 2020

Keep up the fight!

New to solar - Looking to install 24v/MPP lv2424-3.5kw-2/270w panels

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