How much lithium is enough for 1000watts of solar?

[T1 Terry]

Originally Posted by noelex 77

Having lots of panels in series is usually the easiest and cheapest system to install, but is also the least effecient in a marine environment with plenty of shaddow sources. A parallel configuration is more efficient especially for higher voltage panels. Multiple controllers are the most efficient.




Using an undersized solar controller such as one with 100A limit with a 1500w solar array and 12v system will harvest less energy than using a larger controller (or even better multiple controllers with a larger total capacity). Using an undersized controller will be less expensive but will not harvest more solar in less than optimal days.

Each to their own. If you have a system that requires more than 100 amps per hr for more than 6 hrs, then yes, you need a lot more solar and more controllers. As far as a controller per panel, good luck with getting them to all work together, they would need to be in a bluetooth network with a battery voltage monitor in the network as well to tell every controller what the true battery voltage is, not the voltage it senses in the cable that it is trying to push the charging current down.
If you want to connect all the panels in parallel, you will need blocking diodes on each positive solar input if you have multiple panels into a single controller, otherwise the shaded panel will suffer the back feed current pushed out from any full sun panels, it's just the path of least resistance.
Blocking diodes are not the diodes you see in the solar panel junction box, they are bypass diodes to pass the current from other panels in series from the in to the out if that panel is in shade.

The higher the string voltage, the lower the percentage loss between the source and controller.
In the example I posted, any single panel of the 11 in series that is not in shade will still produce at its best possible output, any partially shaded that can produce a bit from the unshaded section (if each section has bypass diodes), will add to the solar harvest.
Until Victron came out with the networking solution between solar controllers and the BMV, I did and recommended much as you are saying, but that ability to network changed the whole thing. The controller no longer needs to stop charging to sense the battery voltage, nor does it sense the raised voltage created by another charging device pushing current into the system, the BMV is boss and tells the controllers what the battery voltage is so it doesn't have to sample the line voltage.
The only catch with panels in series, they all need to have the same VOC and VMP to get the results you expect, the upside is smaller cable size between the panels and controller because doubling the voltage reduces the resistance loss to near enough to 75% rather than the 50% you would expect.

T1 Terry

[noelex 77]

Originally Posted by T1 Terry

As far as a controller per panel, good luck with getting them to all work together, they would need to be in a bluetooth network with a battery voltage monitor in the network as well to tell every controller what the true battery voltage is, not the voltage it senses in the cable that it is trying to push the charging current down.

This is all very easy to do. The popular Victron controllers will do this automatically.

Originally Posted by T1 Terry

If you want to connect all the panels in parallel, you will need blocking diodes on each positive solar input if you have multiple panels into a single controller, otherwise the shaded panel will suffer the back feed current pushed out from any full sun panels, it's just the path of least resistance.
Blocking diodes are not the diodes you see in the solar panel junction box, they are bypass diodes to pass the current from other panels in series from the in to the out if that panel is in shade.

Blocking diodes are rarely beneficial in a system with a solar controller. The loss induced by the diode is almost always greater than the energy saved and you have added another failure point. If you are concerned it is easy to measure the current consumed by a totally shaded panel. It does vary, but for most panels the current is extremely tiny. Solar cells are effectively a diode.

Originally Posted by T1 Terry

The only catch with panels in series, they all need to have the same VOC and VMP to get the results you expect

You are confusing series with parallel connection with this statement. Solar panels should have the same output current to be connected in series. Solar panels should have the same output voltage to be connected in parallel.

[T1 Terry]

Don't want to start a war here, I have been doing this for over 11 yrs now and have more than 200 systems out in the wild that do my field testing for me, so I;m speaking from proven knowledge earned the hard way, if it doesn't work then make it work at my own cost ..... so I make sure it actually works before it leaves the yard ...... two trips from Mannum to Perth is quite enough for me to learn to test to the last degree and learn to read the customer and not be afraid to say no ... or to simply pull the whole lot out and give them their money back ....

Schottky diodes have very little loss to heat, these are the same as the diodes used as bypass diodes in all solar panels made for many yrs now, if you doubt my claim about a shaded panel being turned into a heater, try looking at a shaded panel in an otherwise sun drenched array with a thermal camera, you will see what you would expect to be a cooler panel actually showing up as a much hotter panel.
Companies such as this one, https://www.solar4rvs.com.au/mc4-in-...-connector-15a learned the hard way with their semi flexible solar panels and massive failure rates in systems in parallel and in series systems linked in parallel before the controller .....

T1 Terry