Now that I can leave the inverter on all the time, some items can be wired to the inverter permanently.  Lighting is a key item.  First thing noticed when the power fails at night.  No more wandering around in the dark for a flashlight.  Power goes off in my home, lights will operate despite the condition of the grid.  Other things like the washing machine, can be wired to the inverter.  I wrote an article for the Rubicon website on using alt-power for a washing machine.  Here's a link to that article.  Takes about 250 WH to wash a load of clothes (worst case).  TVs, battery chargers for cordless tools, etc, all moving over to alt-power. 

I don't expect a huge difference in my power bill.  I will see a difference, but the big power hogs are still my water heater, and air conditioner.  I'm in FL, and Summers are HOT.  I did just swap my 19 year old A/C unit (8 SEER), for a half-ton larger 14 (SEER) unit.  Electric bill has already dropped $40 since the previous month, and it's no cooler this month.  My main reason for going with alt-power is due to outages during storms.  I will continue moving the lower wattage items off the grid.  Some year it might pay for itself, but it won't be anytime soon.

The installation of the additional two panels is much like the previous two.  It did exceed the capabilities of the ProStar 30M charge controller, so having to use my MorningStar 10L controller as well.  Details below.

Everything that's brought up on the roof comes up the ladder.  Keep that in mind when buying panels.  130 Watt panels are about as heavy/awkward as I'd want to carry up a ladder solo.

The array gets two more panels.  Still using the RV type mounts.  Drilled holes through the shingles & plywood, used 100% silicone clear caulk, and stainless steel bolts & washers, then covered the heads of the bolts with more caulk. 

Hard to tell from this picture, but a storm was rolling in quickly as I finished up.  No place to be during lightning!

All the panels are holding up well in the FL environment.  Sun, heat, rain, small hail, tropical storms, so far, no issues.  These are low profile, and generally not in the path of any flying debris.  615 Watts worth.  Now I need to install the other Harbor Freight 45 Watt kit, which has been collecting dust in my garage.  That'll give me 660 Watts, exceeding my 500 Watt goal for the Summer.

The charge controllers determine how much charging the batteries get based on Voltage.  Once the battery bank Voltage has come up, the charging slows or even stops at times.  This makes it difficult to see a charging improvement with more panels on the roof!  So to force the issue, I connected my shop vacuum, putting a 100 Amp (DC) load on the system.  The sudden Voltage drop caused the charge controllers to start drawing available energy from the solar panels.

Here's the load on the inverter with the vacuum running.

The LinkPRO monitor shows a net loss of 74 Amps per hour.  Note the minus symbol.  100 Amp load, minus ~25 Amps of charging, = 74 Amps displayed.  This display shows what's going in/out of the battery bank.  Important that you keep in mind this is the net value.  Doesn't show what's going in and out of the battery bank, just the difference between the two.  From the battery standpoint, this is really all that matters.

With the load turned off, a small arrow icon next to the battery symbol denotes charging.  Now energy is going into the battery bank. 

The ProStar is limited to 30 Amps, so one of the 130 Watt panels is on the other controller.  By using a clamp-on DC meter, I could see a total of almost 25 Amps coming from the solar array.  I'm measuring the output of both charge controllers at this time.

The MorningStar controller on the left has one 130 Watt panel connected to it.  The ProStar controller is on the right.  5.87 Amps + 18.2 Amps = 24.07 Amps, or about what was measured with the clamp-on meter in the other picture.  If the battery bank was more depleted, I expect the charge rate to be even higher.  615 Watts x 0.7 (derating factor) = 430.5 Watts available / 12 Volts = 36 Amps.

Last updated 8/25/09    All rights reserved.