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cost analysis of small controller / panel combinations
For about the same price a second solar panel can give 100% more power. Above about 300 to 400 watts MPPT is financially advantageous.
A fair rule of thumb. It gets distorted a bit at 200w because PWM controllers can't be overpaneled, requiring an upgrade there.
I ran some numbers, using Renogy gear where possible:
raw cost
In terms of initial investiment, from least expensive to most expensive
shunt + poly panels. Shunts have similar performance characteristics to PWM but are simpler.
Smart charging may not be available. They tend to be very cheap, $1 per rated amp.
shunt + mono panels (not recommended due to low Imp)
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PWM + mono panels (not recommended due to low Imp)
overpaneled MPPT + whatever panels are cheapest. In this model a slightly undersized (and therefore less expensive) controller is used.
1)
MPPT + whatever panels are cheapest
Morning, ideal
(12.1v), 50deg F, perfect insolation
ranked by output
20A MPPT 200W poly/mono, 174.80W @ $1.65/W. $289.
20a PWM 200w poly 125.89W @ $1.99/W. $250.
10a MPPT 100W mono/poly 87.4W @ $1.84/W. $161.
10a PWM 100W poly 62.94W @ $1.82/W. $115.
10a PWM 100w mono 59.25W @ $1.93/W. $115.
ranked by $/watt
20A MPPT 200W poly/mono, 174.80W @ $1.65/W. $289.
10a PWM 100W poly 62.94W @ $1.82/W. $115.
10a MPPT mono/poly 87.4W @ $1.84/W. $161.
10a PWM 100w mono 59.25W @ $1.93/W. $115.
20a PWM 200w poly 125.89W @ $1.99/W. $250.
Morning, 75% insolation
(12.1v), 75% insolation - ranked by $/watt. I did not calculate mono on these, as PWM performs better on poly and MPPT doesn't care.
10A MPPT 200w mono/poly, 121W @ $2.16/W. $261.
10A PWM 100w poly, 47.21W @ $2.42/W. $115.
10 MPPT 100w mono/poly 65.55W @ $2.46/W. $161.
20A PWM 200w poly 94.42W @ $2.76/W. $250.
Same information ranked by output:
10A MPPT 200w mono/poly, 121W @ $2.16/W. $261.
20A PWM 200w poly 94.42W @ $2.76/W. $250.
10 MPPT 100w mono/poly 65.55W @ $2.46/W. $161.
10A PWM 100w poly, 47.21W @ $2.42/W. $115.
Afternoon, ideal
(14.6v), 70deg F, perfect insolation - ranked by $/watt
10A PWM 100w poly 82.05W @ $1.39/W. $115.
10A PWM 100w mono 77.23W @ $1.48/W. $115.
20A PWM 200w poly 164.10W @ $1.52/W. $250.
20A PWM 200w mono 154.47W @ $1.62/W. $250.
20A MPPT 200W mono/poly 165.27W @ $1.75/W. $289.
10A MPPT 100W mono/poly 82.63W @ $1.95/W. $161.
same data sorted by output:
20A MPPT 200w mono/poly 165.27W @ $1.75/W. $289.
20A PWM 200w poly 164.10W @ $1.52/W. $250.
20A PWM 200w mono 154.47W @ $1.62/W. $250.
10A MPPT 100W mono/poly 82.63W @ $1.95/W. $161.
10A PWM 100w poly 82.05W @ 1.39/W. $115.
10A PWM 100w mono 77.23W @ $1.48/W. $115.
Afternoon, 75% insolation
(14.6v), 75% insolation - ranked by $/watt.
10A PWM, 100w poly, 61.54 @ $1.62/W. $115.
10A MPPT, 200w mono/poly 146.0W @ $1.79/W. $261.
20A PWM, 200w poly, 123.08W @ $2.12/W. $250.
10A MPPT, 100w mono/poly, 61.99w @ $2.60/W
Same information, sorted by output:
10A MPPT, 200w mono/poly 146.0W @ $1.79/W. $261.
20A PWM, 200w poly, 123.08W @ $2.12/W. $250.
10A MPPT, 100w mono/poly, 61.99w @ $2.60/W
10A PWM, 100w poly, 61.54 @ $1.62/W. $115.