Solar book recomendation

[BlueMaxx]

Can someone suggest a good book on Marine Solar theory and outfitting?
There is just so much out there it is hard to wade through, and some is dated.


Thanks,



M

[DefinitelyMe]

I don't know any books i'm afraid but this website is excellent. There's quite a lot to read but it's entertaining and very, very informative:

https://handybobsolar.wordpress.com/

He's talking about systems on RVs, but it's pretty much all directly transferable to a boat. Enjoy!

[socaldmax]

Originally Posted by DefinitelyMe

I don't know any books i'm afraid but this website is excellent. There's quite a lot to read but it's entertaining and very, very informative:

https://handybobsolar.wordpress.com/

He's talking about systems on RVs, but it's pretty much all directly transferable to a boat. Enjoy!

He's a pretty good source, especially in regards to proper (higher) charging voltage for batteries, most battery banks are only charged to 80%, giving only 30% of cap instead of 50%.

My only caution about his solar system design philosophy is he did it and wrote it back when solar panels were $8/watt and copper cable was cheap. This encouraged him to use 2AWG cables for a measly 200w of solar. Now things have changed and solar panels are more efficient, much higher capacity, much cheaper (I've seen 59 cents/watt) and copper cables are a lot more expensive.

Lately, I've been inclined to install more and larger panels (if room permits) and settle for 6 AWG cable rather than 4AWG, the extra loss might be minimal compared to the output of 600w of solar vs 200w of solar back in the old days.


If the OP has any questions, we've had some great threads on solar system design, etc here on CF, or if he has a specific question, go ahead and ask it here, plenty of knowledgeable people here and there are a number of design principles that we all seem to agree on.

[DefinitelyMe]

Originally Posted by socaldmax

He's a pretty good source, especially in regards to proper (higher) charging voltage for batteries, most battery banks are only charged to 80%, giving only 30% of cap instead of 50%.

My only caution about his solar system design philosophy is he did it and wrote it back when solar panels were $8/watt and copper cable was cheap. This encouraged him to use 2AWG cables for a measly 200w of solar. Now things have changed and solar panels are more efficient, much higher capacity, much cheaper (I've seen 59 cents/watt) and copper cables are a lot more expensive.

Lately, I've been inclined to install more and larger panels (if room permits) and settle for 6 AWG cable rather than 4AWG, the extra loss might be minimal compared to the output of 600w of solar vs 200w of solar back in the old days.


If the OP has any questions, we've had some great threads on solar system design, etc here on CF, or if he has a specific question, go ahead and ask it here, plenty of knowledgeable people here and there are a number of design principles that we all seem to agree on.

Yup, i completely agree. He does address the cable size issue somewhat in one of his most recent articles, just by saying that it needs to be sized appropriately, but bigger is not always better. Personally, i found it was more cost effective to buy thinner, lighter, cheaper cables, wire the panels in series to mitigate voltage drop that way and then spend a little extra on a really nice charge controller that can cope with the high voltage input.

Yup, it's possible to find some really cheap panels now, especially if you've got the space to buy the industry standard-sized panels that people stick on their houses and stuff. Less than $1/W is the norm now for those panels.

[Stu Jackson]

http://www.cruisersforum.com/forums/...up-147758.html

[BlueMaxx]

Thanx!

[mstrebe]

Cable size is 100% about amperage, not wattage and zero to do with voltage. By wiring in parallel, you're keeping the amperage of one panel and multiplying voltage, so the size of cable sufficient for one panel works. The advice to wire in series and increase voltage rather than amperage will save quite a bit of money and cable weight.

[noelex 77]

Originally Posted by mstrebe

The advice to wire in series and increase voltage rather than amperage will save quite a bit of money and cable weight.

There has been a lot of debate about series and parallel connection. As you point out, series connection reduces the cost (and difficulty) of thick wiring. On the downside, while it is not entirely clear, the consensus is that that the performance suffers in partial shade. Partial shading of the solar panels is very common for a boat.

Series connection can only be done with an MPPT controller. Units that will cope with the higher voltage seen with series connection will tend to be more expensive, at least for the larger panels.

Finally when in series, voltage can quickly reach the dangerous or even potentially fatal level. Many people mistakingly believe because it is DC it is safe.

So there are a number of pros and cons to debate when deciding whether to wire the panels in series, parallel or a mixture. It is not as simple as selecting the option with the cheapest wiring.