Having large solar panels, DC to DC setup from tug plus lithium battery, remaining off grid is still limited by conditions of use by owner. Recently while camping had a "fairly experienced" neighbour speak to me about his problems with his very late modern camper trailer. It had all the latest bells and whistles including 2 huge solar panels which entirely covered the top of trailer. Plus DC to DC arrangement, two batteries in tug, MPPT lithium compatible controller plus 1 X 100amp lithium battery. He moaned that he and partner only able to stay off grid for 3 days before having to recharge system again. That immediately pricked my interest as to why!
On investigation, found that when the roof is raised, the solar panels which act as roof for the limited sleeping accommodation are at an angle of 70 to 80 degrees from the horizontal ( nearly vertical) which means that really only effective if at right angles to the sun in early morning or late afternoon. As he had van parked east west, the panels were facing south and through fairly heavy tree foliage above. Asked why parked that way, he replied had to stop sleeping down hill and wanted to be in the shade!!! Also, panels flush on roof and completely enclosed by aluminum angle brackets - no air gaps at all!! Up to 15% loss of generation when panel temp is around 55C! Don't some van manufacturers ever talk to the electrical/solar experts??
He didn't use the DC to DC whilst camped as usually away most of day in tug leaving van to look after itself. Dealer told him battery would be charged up by time he gets to next spot.......time/distance not mentioned!
When asked about electrical usage in kitchen area , (had lots of 240 volt power points available everywhere), said only use power for large compressor fridge/freezer and lights outside and in sleeping area. Upon further questioning, finally admitted that they are both keen coffee drinkers and usually have 3 cups per day each, ( breakfast, lunch and dinner), courtesy of 3000w inverter. While I was picking up my jaw, he added that they also use their induction cooker and electric kettle at times rather than gas. The dealer said it would be fine as solar panels were capable of at least 30 amps and would recharge lithium battery quickly. Yeah, right, if roof down and panels at a lesser angle than 70 or 80 degrees!!!
Apparently only got part of the story as also muttered about dealer had set his battery limited to only 50% of capacity to prevent damage.
Also had a you beaut blue tooth controller which indicated that he lost 10% of battery capacity every time he used inverter for short time and rarely saw battery capacity higher than 60%., except when just arriving a new camping spot! DC to DC charging??
So they are out there!! And the dealer told them they would be right for any eventuality, just like home on the grid. No matter how much or how little electrical generating/storage equipment you have, it always boils down to how you use it!!
