combiner box for solar
So is anyone using a combiner box for two 100w solar panels. What I see I really don't need it even with hooking them up parallel. I going into a MPPT20 charge controller. Using the system for battery...
Forum Discussion
No combiner needed.
Also, If you have not make the MPPT purchase.. I would suggest a larger PWM (for the same amout of money, or less than the MPPT)
The reason as mentioned above by Bend is that MPPT do not perform well on a small system. Also they do not proform very well with a hotter climate, or when the system will normally be in a charged state. (this may or may not be your case, for me it would be because for at least the next year I'll be camping 1 week at a time)
Below is information from MorningStar's site about their own MPPT vs PWM controllers.
"1. Low power (specifically low current) charging applications may have equal or better energy harvest with a PWM controller. PWM controllers will operate at a relatively constant harvesting efficiency regardless of the size of the system (all things being equal, efficiency will be the same whether using a 30W array or a 300W array). MPPT regulators commonly have noticeably reduced harvesting efficiencies (relative to their peak efficiency) when used in low power applications. Efficiency curves for every Morningstar MPPT controller are printed in their corresponding manuals and should be reviewed when making a regulator decision. (Manuals are available for download on the Morningstar website).
2. As explained in the Environmental Considerations section, the greatest benefit of an MPPT regulator will be observed in colder climates (Vmp is higher). Conversely, in hotter climates Vmp is reduced. A decrease in Vmp will reduce MPPT harvest relative to PWM. Average ambient temperature at the installation site may be high enough to negate any charging advantages the MPPT has over the PWM. It would not be economical to use MPPT in such a situation. Average temperature at the site should be a factor considered when making a regulator choice (See Appendix).
3. Systems in which array power output is significantly larger than the power draw of the system loads would indicate that the batteries will spend most of their time at full or near full charge. Such a system may not benefit from the increased harvesting capability of an MPPT regulator. When the system batteries are full, excess solar energy goes unused. The harvesting advantage of MPPT may be unnecessary in this situation especially if autonomy is not a factor.
Also, If you have not make the MPPT purchase.. I would suggest a larger PWM (for the same amout of money, or less than the MPPT)
The reason as mentioned above by Bend is that MPPT do not perform well on a small system. Also they do not proform very well with a hotter climate, or when the system will normally be in a charged state. (this may or may not be your case, for me it would be because for at least the next year I'll be camping 1 week at a time)
Below is information from MorningStar's site about their own MPPT vs PWM controllers.
"1. Low power (specifically low current) charging applications may have equal or better energy harvest with a PWM controller. PWM controllers will operate at a relatively constant harvesting efficiency regardless of the size of the system (all things being equal, efficiency will be the same whether using a 30W array or a 300W array). MPPT regulators commonly have noticeably reduced harvesting efficiencies (relative to their peak efficiency) when used in low power applications. Efficiency curves for every Morningstar MPPT controller are printed in their corresponding manuals and should be reviewed when making a regulator decision. (Manuals are available for download on the Morningstar website).
2. As explained in the Environmental Considerations section, the greatest benefit of an MPPT regulator will be observed in colder climates (Vmp is higher). Conversely, in hotter climates Vmp is reduced. A decrease in Vmp will reduce MPPT harvest relative to PWM. Average ambient temperature at the installation site may be high enough to negate any charging advantages the MPPT has over the PWM. It would not be economical to use MPPT in such a situation. Average temperature at the site should be a factor considered when making a regulator choice (See Appendix).
3. Systems in which array power output is significantly larger than the power draw of the system loads would indicate that the batteries will spend most of their time at full or near full charge. Such a system may not benefit from the increased harvesting capability of an MPPT regulator. When the system batteries are full, excess solar energy goes unused. The harvesting advantage of MPPT may be unnecessary in this situation especially if autonomy is not a factor.
