Lazy Daze Owners' Group

Hello Sawyer - it appears as if many owners who use three or more solar panels are adding additional batteries. Here is picture from AM Solar showing two additional 300Ah 6V AGM 6CTs batteries and other gear installed under the bench in a 1998 LD 26.

Here is the AM Solar link: 1998 Lazy Daze w/ Chevy Chassis, 26’

“Is there a information source which suggested that running six panels in series-parallel pairs would make the MPPT happy?”

Most MPPT controllers generally are happiest (most efficient) with 36 volts or more coming in from the panels. That gives them plenty to work with. And here’s a key point: many solar controllers won’t even begin to pump out juice to the battery until the input voltage from the panels exceeds a certain threshold, such as 5 volts above the battery voltage. That means early in the morning when the sun is low and the voltage from the panels is likewise, the controller has to wait until the threshold is reached. With 18V panels, that can take a while. With panels in series putting out twice as much voltage, it happens much sooner. In short, series-connected panels plus an MPPT controller equal a longer effective solar day. (That’s not to mention that when voltage is doubled, voltage drop in the wires is cut in half.)

Now, I should add that more voltage isn’t always better. For example, Blue Sky’s otherwise good controllers have relatively modest maximum voltage ratings (you have to read the fine print to realize just how limited they are), and can be damaged if voltage exceeds those limits, as it might on a cold day with a series hookup.

Even if you have a controller that can handle higher input voltages, such as the Victron Smart Solar series, it doesn’t make sense to connect all your panels in series, because then you are vulnerable to the partial-shading effect I mentioned earlier. Yes, the effect is real; it’s just not as much of a bugbear as some “parallel-only” traditionalists suggest. Connecting panels in series-parallel pairs is a good way to gain the benefits of a series hookup while minimizing the chance that your whole array will be affected by a single shaded panel. (Of course that means you must have an even number of panels—two, four or six.)

“I am curious if anyone knows what manufacture and model numbers are for the respective components.”

Panels: Renogy’s 100 W panels have proven reliable and affordable over the years. Their best value is this $135 panel. Their high-efficiency Eclipse panels are smaller, so you can fit more of them in your available space, but they’re much more expensive - and they are currently out of stock in most places. (AM Solar carries what I believe is the Eclipse panel, but it’s twice as expensive per watt.)

Charging controllers: Blue Sky, Morningstar and Victron all have their advantages—there’s no perfect controller. I’ve used all three brands at various times, but I’ve been using Victron controllers for some years now, and for me they are the best compromise. Their current models have built-in Bluetooth, which means you can monitor all their functions (and adjust their settings) from a smartphone or tablet. No need to mount and wire up monitor panels—and Victron’s iPhone/iPad app presents more information, and does it more clearly, than any solar controller display I’ve seen.

For a system with only a couple of panels, Victron’s $120 SmartSolar 75/15 is a good choice. It can handle up to 75 V and 15 A. I use one of these in my truck, where a single 100 W panel charges a group 27 Lifeline AGM battery that in turn powers a compressor fridge. (This setup is entirely independent of the truck’s electrical system.)

If you have four or six panels, Victron’s 100/30 controller is a better choice. I use one of these in my Airstream, which has six 100 W panels on the roof, and my Lazy Daze had a similar setup.

Of course, as others have pointed out, there’s not much point in having lots of solar panels unless you have enough batteries to store the power. I had about 500 Ah worth of AGMs in the Lazy Daze, and I have 320 Ah of lithium batteries in the Airstream. (For various reasons, one doesn’t need as large a bank with lithium batteries. But they cost an arm and a leg, so they’re probably not the best choice for a small system.)