Practical aspect of sizing solar panels?

[Delancey]

As far as sun protection goes I am thinking the solar arch will function pretty much the same as a Bimini depending on how many panels and where it goes. Personally, I'm just not a davits kinda guy so that's not really an option for me.

When you say you are thinking about adding more panels, I take it your current panels are on the Bimini and the future ones will go on the davits?

[noelex 77]

Great thread.
Solar panels have got (relatively) inexpensive so the emphasis has rightly moved from calculating the minimum that you can get away with to just installing the most you can reasonably fit in.

A thread about sharing experiences and quantifying the amount and how to install it is great to see.

I could tell tales of of when I made the big jump from a (single) 43w panel to a 75w panel and thought we had power to burn (no diesel, or shore power so that was all we had). The good bad old days

[sparrowhawk1]

Originally Posted by Delancey

As far as sun protection goes I am thinking the solar arch will function pretty much the same as a Bimini depending on how many panels and where it goes. Personally, I'm just not a davits kinda guy so that's not really an option for me.

When you say you are thinking about adding more panels, I take it your current panels are on the Bimini and the future ones will go on the davits?

Yes I'm replacing two smaller panels on my davits with four larger panels. Will put the 2 smaller panels on my deck. Most small power boats that have arches that are also bimins so I guess it's just terminology but its cheaper to have a standard Bimini than a welded large pipe arch. While the large pipe arch will be less intrusive

[piloto]

Delancy, it's about real estate and load profile. The loads need to be quantified on a daily watt hour basis and, ideally, matched by input from the panels on a equal watt hour basis of production per day (with some reserve if possible). There is no "rule of thumb" except, perhaps, the "mo is betta" approach. Once you've quantified the loads, you can address with inputs, possibly considering a small wind gen for supplement to the solar. If you can find enough realestate on the boat to provide the input, then you have it licked. Choices of electrical usage items geared towards efficiency should be the first approach, then satisfying the load requirement with solar & wind first, generator and engine consuming fuel last. Energy efficiency = cost efficiency in operation protocol. Burning diesel or gas to make watt hours or amp hours at $5+/gal is money better spent on photovoltaics or wind, if you can find the space to put them. Example: there are watermakers out there that make 20-30 gpd using 8-12amps or 3 to 4 amps. Choosing the more energy efficient model will allow your renewable energy generated watt hours to go 3 times as far. Same with all other electrical usage items-lighting, radios, entertainment systems, etc. if you would like a load sheet to help you figure out the system demands, let me know and I will send you one that will walk you through the calculations.

[Mhorowitz]

I started w an 80 watt panel on the davit and of course that didn't do much. We added two 135 w panels over the Bimini and while that doesn't completely stop us from running the engine or genset from time to time it works quite well. Today I might go for 185-230 w panels instead but at the time it was way expensive 2008, and I did not want the panels to extend beyond the Bimini

[RaymondR]

One of the problems I am finding with panels is that the sorry beggars that design them keep changing the sizes.

I started out with 2 x 80W panels in a beautifully made SS frame and when I went to replace them found they no longer make them that size so I decided to go industrial and threw away the SS frame and built one out of aluminum. That was about four years ago and I recently had to change two of the panels because of low output and found that I could not get any the same size as the old ones and am now rebuilding again. Fortunately I need only buy some fairly inexpensive alloy sections and bolt them into place so the size change is not a big problem now.