Hello Gents,
I reaching to you because I need your insights to make an enlighten decision about the best solar system design for my use case.
I read a lot of posts about MPPT and PWM controllers and I believe I have a good understanding of the pros and cons of each technology. My goal is not to starts another post about MPPT and PWM controllers but rather to try to find the optimal design that will allow me to deal with shading.
We are typically camping from early June to late September and the temperature during that period varies from 5 to 30C. The power budget is ~50 Ah/day with (weather factor included) roughly 2.5 hours to recharge the batteries bank thus suggesting a solar array that can provide something like 25 Amps.
The batteries bank, according to my power budget, should provide 3 days of sunless autonomy with a DoD of 50%. I guess that the bank should be roughly around 83% Dod each day.
The panels layout is a single row on the awning's side near the front of the trailer to maximize their chances to be exposed to sunlight. The opposite side and the back of the trailer are typically closer to trees. I'm also planning to tilt the panels so their backs will be as the same level as the AC cover's top in a attempt to minimize the risk of having the AC casting shades on them and improve exposure to sunlight. Those precautions obviously won't not be enough to prevent shading but a guy has to start somewhere. roof model.jpg
I will be using a junction box on the roof in order to ease wiring the panels in series or parallel and to have a single pair of wires going down to the batteries bank. I would also like to keep the wire to the battery bank as small as possible to ease fishing them around.
The components I'm considering for that project are:
My previous readings involving shading issues would either suggest:
I must admit that the MPPT from a technical point of view is very appealing, regardless if the 12 volts panels were to be in series or parallel just by the fact that the bulk charge period can benefit, even if its not always optimal, from a current boost.
I also saw the Gone with the Wynns : Sailboat Solar Power - Series vs. Parallel & Shading video: https://youtu.be/1qD3mN8VotQ, in which I believe they are making use of an Outback Flexmax MPPT charge controller, and end up recommending to wire the solar array in parallel.
This brings me to my question, lets say we vent the MPPT vs PWM economical factor and only focus on harvesting as much power as possible from a solar array that will be knowned to be exposed to varying shading conditions.
What would your experience recognize as the best setup to deal with the potential shading caused by the surrounding trees.
Would it be:
Thank you
Marc
I reaching to you because I need your insights to make an enlighten decision about the best solar system design for my use case.
I read a lot of posts about MPPT and PWM controllers and I believe I have a good understanding of the pros and cons of each technology. My goal is not to starts another post about MPPT and PWM controllers but rather to try to find the optimal design that will allow me to deal with shading.
We are typically camping from early June to late September and the temperature during that period varies from 5 to 30C. The power budget is ~50 Ah/day with (weather factor included) roughly 2.5 hours to recharge the batteries bank thus suggesting a solar array that can provide something like 25 Amps.
The batteries bank, according to my power budget, should provide 3 days of sunless autonomy with a DoD of 50%. I guess that the bank should be roughly around 83% Dod each day.
The panels layout is a single row on the awning's side near the front of the trailer to maximize their chances to be exposed to sunlight. The opposite side and the back of the trailer are typically closer to trees. I'm also planning to tilt the panels so their backs will be as the same level as the AC cover's top in a attempt to minimize the risk of having the AC casting shades on them and improve exposure to sunlight. Those precautions obviously won't not be enough to prevent shading but a guy has to start somewhere. roof model.jpg
I will be using a junction box on the roof in order to ease wiring the panels in series or parallel and to have a single pair of wires going down to the batteries bank. I would also like to keep the wire to the battery bank as small as possible to ease fishing them around.
The components I'm considering for that project are:
- A set of monocrystalline solar panels either:
- three 12v 160W
- four 12v 100W
- A 12v batteries bank composed of 2 xCrown CR-330 6 volts batteries in series.
- A Bogart Engineering Trimetric 2030 battery monitor
- A charge controller either:
- Bogart Engineering SC2030 (30 Amps) linked to the Trimeric 2030
- Morningstar PS-MPPT-40 (40 Amps)
My previous readings involving shading issues would either suggest:
- To wire the panels in parallel and use a PWM charge controller
- To wire the panels in series, benefiting from the panels' bypass diodes, and use a MPPT controller
I must admit that the MPPT from a technical point of view is very appealing, regardless if the 12 volts panels were to be in series or parallel just by the fact that the bulk charge period can benefit, even if its not always optimal, from a current boost.
I also saw the Gone with the Wynns : Sailboat Solar Power - Series vs. Parallel & Shading video: https://youtu.be/1qD3mN8VotQ, in which I believe they are making use of an Outback Flexmax MPPT charge controller, and end up recommending to wire the solar array in parallel.
This brings me to my question, lets say we vent the MPPT vs PWM economical factor and only focus on harvesting as much power as possible from a solar array that will be knowned to be exposed to varying shading conditions.
What would your experience recognize as the best setup to deal with the potential shading caused by the surrounding trees.
Would it be:
- To wire the panels in parallel and use the PWM controller
- To wire the panels in series and use the MPPT controller
- To wire the panels in parallel and use the MPPT controller
Thank you
Marc
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