Solar Panel, add more or replace

[Bewildered]

My boat came with 2 solar panels fitted I have no idea how old they are or what type, I did find out from a previous owner that he thinks they are 140w and 80w. They were fitted with a cheap PWM controller which I have replaced with a 40amp tracer unit. This has made some improvement to how much power they are generating, but as a live aboard continual cruiser I want more power.

The plan was originally to add another panel or two at a later date. However I was wondering if it would just make more sense to replace them with new higher wattage panels rather than mix them with new lower wattage.

The tracer should be able to take 480watts of panels (480w/12v = 40amp, although Bimble state on their site that the 4215BN can take 520w of panels, I assume that they are built with a tolerance that can be over powered but don't expect the panels to max out that often?) so I can either fit another 260 or so watts of new panels to my existing array or replace with say a pair of new 250w units.

the first option would be cheaper but the second option would probably perform better and take up less roof space therefore looking tidier. Also panel technology has moved on since these were fitted and I'm not sure how I can find out what type I have.

So what would be the general consensus?

[rusty69]

If you decide to replace,and also still have the PWM,you could use the old panel on the engine battery, space permitting.

[sirweste]

Interested in this topic, I find myself in the exact same position having bought the same MPPT Tracer. Two old 100 W panels, keep em and add more panels all through the Tracer. Or swap them. Or add new panels on the Tracer and reinstall the PWM for the old panels (least likely option).

 

[cuthound]

Interesting article of solar panel lifespan.

Seems one early installation is still functioning after 60 years.

The inverters associated with domestic installations do not fare so well, they suggest a 5-10 year lifespan. When I was working most commercial solid state inverters lasted 10-12 years. Mechanical (rotary) ones lasted longer but needed far more maintenence  (bearings etc).

[Detling]

Best not to mix panels of different wattage. If in series the max current will be the max of the smallest. If in parallel and same voltage there is no problem though.  If of different voltages you should not put them in parallel as either the lowest voltage will be fried ,or the voltage will be limited to the lowest panel, I have not tried to find out which happens.

 

It will probably be best to get two house type panels 250 or 300 watts each through the new controller and use the old system to charge the engine and if fitted bow thruster batteries.