Planning Solar Panels
Hi everyone, I'm working on my very first DIY camper conversion, using a 2010 extended Ford E250. I was looking at solar panels yesterday, I was going to make the move eventually but maybe soone...
Forum Discussion
Boon Docker wrote:
Anyone wanting to know the pros and cons about controllers, here is a white paper on the subject. Very interesting read that takes away all the heresay that you read on the forums.
/shrug I can pull up numerous white papers from any number of vendors that write the paper to point you in their marketing direction.
Does a vendor want you to spend $450 or $150... lets make a white paper look pretty so people will.
The FACT is, PWM will usually always perform better in a camper/RV type set up. Period. Even the small gain you may see in an MPPT is NOT worth the cost of the controller. Use the money for another panel, and/or better wire, and you would be on top again.
Fun points:
>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.
>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.
>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 regardless of array size). MPPT regulators commonly have noticeably reduced harvesting efficiencies (relative to their peak efficiency) when used in low power applications.
