Serial, Parallel, and how many controllers

[jbinbi]

Please see the diagram attached. The boat will be on a mooring, normally facing south(ish). Boat will be used 99% of the time for daysailing, hopefully a few times a week. But very little engine usage. Possibly under 15 min per sail.I have 250Ah AGM. Most of my electronic uses are instruments w AP and refrig. Ideally, I would like to always leave fridge on so when I get on board I have cold drinks.

I am only able to get a 50W flex panel on each side of the dodger.

On the bimini I can get a 175 in the back middle. I can put a 50W in the front section of the bimini between the viewing windows.

1. Do you think it is worthwhile to put the 50W panel in front of the 175, and I was thinking of wiring them in serial, then to the controller?
2. I would think the best solution would be 3 controllers, one for each on the dodger and one for the bimini all run in parallel. However, with only 50W controllers, I am wondering about the expense of separate controllers? Very familiar with Victrons, but they are pricey. Do I need 3? Any other brand besides victron or mastervolt?
3. On a previous boat with victrons, I setup a secondary electric cooler to turn on at a specific V from the victron controller's load output, which has a programmable voltage. Is it worth it to turn off regular refrig breaker when leaving the boat, but wire in parallel to the fridge the output load from the controller. Usually the fridge will turn itself off at a specific V, but I think it is like 12V and not sure I want to run my battery that low just to keep drinks cold?

[donradcliffe]

You shouldn't wire panels of different wattage in series, or different voltage in parallel.

There are cheaper controllers than Victron. If you are buying in the 30 amp range, I have had good experience with Epever and heard bad things about Renogy. If you are buying in the 10 amp range, its a jungle out there--people are selling PWM controllers labeled as MPPT.

The fridge will take about 750 watt hours per day, and you will need at least 300 watts of panels to ensure the batteries will get recharged daily. Without the fridge you will only need 50 watts.

[jbinbi]

Thanks. The 2 panels on the bimini, 175 and 50 won't be outputting the same voltage at the same time, VOC on 175 is 24, VOC on 50 is 23, but will be different shading, but might be close enough to wire in series. I would think adding the V then putting it into a single mppt controller would work relatively well?

[smac999]

Originally Posted by jbinbi

Thanks. The 2 panels on the bimini, 175 and 50 won't be outputting the same voltage at the same time, VOC on 175 is 24, VOC on 50 is 23, but will be different shading, but might be close enough to wire in

series. I would think adding the V then putting it into a single mppt controller would work relatively well?

Do not wire them together. Get 2 controllers.

225w is not going to run your fridge. It might recharge the battery from the other stuff if fridge is left off.

[jbinbi]

Right you guys are. Thanks, wasn't thinking of this properly, if I put both into one controller I am either current or V limiting output since they are disparate panels both ways.

I think it isn't worth it to even put the 50 in front of the 175 on the bimini for the cost of the panel and another controller vs. it's output.

However, on the dodger, I have the 2 50's on either side of the boom. Again, those being small and since on either side of boom, I figure one will always have some shadow over it. Separate controllers would be ideal, but I am cramped for space, already have the controller from the 175 panel on the bimini. I want to make sure that the panel outputs enough V to deliver a charge to the battery. So I was thinking of wiring in series into the controller? These are mppt controllers. I know parallel is better for shaded, but am worried with 21VOC, if shaded, I might not get past 14V.