08-30-2014, 01:28 PM
There is plenty of room for a difference of opinion on the orientation of solar panels. Having maximum production twice a year as would be the case with a 19 degree slope won't help you if you aren't making quite enough during the winter. In that case you would be best to slope south facing panels 43 degrees to maximize winter production. Although the summer production will be decreased greatly it will still be as much as the winter production due to the longer hours. Select anything in between to match changing loads since you may need more production during the summer because of air conditioning, although it is a truly hard core solar off-gridder that has air conditioning.
Similarly aiming panels east and west to start re-charging the batteries earlier and delay drawing from them later in the day will let you work your batteries less hard and if you are going into float mode for large parts of the day and thereby not even using all the available solar power it's a win-win.
It's important to accept the fact that you will never achieve the nameplate rating of your panels in Puna. When the sky is overcast panel orientation becomes much less critical and having more panels becomes more beneficial. Buy some extra panels and find somewhere to put them where they can see the sky. If every panel is pointed a couple of degrees true north of flat (for the Big Island at least) you will have the satisfaction of melting down your charge controller at noon each summer solstice but you would be seriously hurting during the winter solstice, so not having all panels aimed in the same direction can mitigate that problem since they won't all peak at once. You could buy a larger capacity charge controller but then you would have to install a larger battery bank. The extra panels pointed in different but still useful directions is an alternative. When the sun is bright different banks of panels peak at different times. When the sun went behind clouds all the panels would then charge at the same low rate. This is a relatively recent practice made feasible by the present relatively low cost of panels.
Similarly aiming panels east and west to start re-charging the batteries earlier and delay drawing from them later in the day will let you work your batteries less hard and if you are going into float mode for large parts of the day and thereby not even using all the available solar power it's a win-win.
It's important to accept the fact that you will never achieve the nameplate rating of your panels in Puna. When the sky is overcast panel orientation becomes much less critical and having more panels becomes more beneficial. Buy some extra panels and find somewhere to put them where they can see the sky. If every panel is pointed a couple of degrees true north of flat (for the Big Island at least) you will have the satisfaction of melting down your charge controller at noon each summer solstice but you would be seriously hurting during the winter solstice, so not having all panels aimed in the same direction can mitigate that problem since they won't all peak at once. You could buy a larger capacity charge controller but then you would have to install a larger battery bank. The extra panels pointed in different but still useful directions is an alternative. When the sun is bright different banks of panels peak at different times. When the sun went behind clouds all the panels would then charge at the same low rate. This is a relatively recent practice made feasible by the present relatively low cost of panels.