PV Gap

Daniel Said:

how do I solar power my camper site?

We Answered:

We run a full-size refrigerator, lighting for 500 sq. ft, an entertainment center, a microwave, 2 computers, and a phone signal booster amplifier. We have 800 watts of solar panels, a 60 amp charge controller, 10 deep discharge batteries, and a 2.5 kW inverter. A backup generator runs the table saw- which draws too much power for the inverter- and a 75-amp charger if it's been cloudy for 2 days straight. System has been operating for 3 years, no problems. Will be upgrading to 16 batteries and 1.2 kW of panels this fall so that we can run a freezer and go 4 days without sun before using the generator.

Ethel Said:

looking for power inverter w/automatic power demand on off?

We Answered:

you need to use relays and a sensor that measures current. You will be able to utilize multiple poles and even create a latching relay that would stay on when power is demanded and bypassed manually if desired.

Roland Said:

iam contemplating solar power plus an inverter in my house for electricity , How effective is it?

We Answered:

The Solar constant is 1,366 watts per square meter. I have trouble envisioning metric units, so let's say you get a 4' x 8' solar panel. Ideal energy impingement of the panel would be (1366W/m^2)(32 ft^2)(2.54/100)^2(m^2/in^2)(144 in^2/ft^2) = 4,061 W when the panel is facing the sun perfectly. Even if you track the sun the power received by your panel will vary sinusoidally due to atmospheric attenuation, so the average power you get in the daytime is 0.6366*4,061 = 2,585 W. I'm unsure about the efficiency of solar panels, but I suspect it is no greater than 50%, taking you down to 1,293 W. Motor-generator inverters are capable of delivering up to 94% efficiency, but electronic inverters are limited to a maximum efficiency of 50%. Now you're down to 646 W average power, with a peak of no more than 1,015 W, or about 1 KW per panel. You need to feed the output of the solar panel(s) into a battery (bank) to store up energy for night use, dropping you to an average of 323 W per panel., or fudging a little bit, 3 A. at 110 V. That's enough to power a TV, a computer, and maybe 2 60 W lamps. Sizing the system up to be able to handle your furnace fan and refrigerator will require at least 10 panels to prevent repeated motor or compressor burnout. That's an area maybe 20 ft x 16 ft. The bank of panels or each indivudual panel must be on an equatorial mount (like a telescope) so you can track the sun not only daily, but throughout the year, although annual tracking can be dispensed with if you mount the panels ar an angle of (Latitude - 23.5). If you want to dispense with tracking altogether, multiply the number of panels by at least ?/2. Remember, too, that these calculations are only good for clear days. Cloud cover can render solar panels totally ineffective.

Mildred Said:

Solar panel reads 13.2V but doesnt work with 12V Power inverter?

We Answered:

What is the power rating of your solar panel? It must be larger than the dc to ac power inverter and as one of the other responders said, the dc to ac power inverter has a start up power that is larger than the constant power rating. You should use the solar panel to charge the battery and let the battery do the work of starting and running the inverter. Also as another responder said 13.2 volts is a little shy to fully charge your battery. 14 to 14.5 volts under full load would be better.

Cecil Said:

How to connect two deep cycle / car battery to inverter?( Solar project)?

We Answered:

First off keep in mind that solar can be powerful enough to kill. It can shortout and over heat wires and cause a fire if not hooked up correctly. I have a small 810 watt solar array with 10,800 watts in battery power. It all runs through a 2000 watt inverter. Just to give you an idea of how much power that is there it will run a 5000 BTU A/C unit, My 32 inch TV set, a 13 inch tv in the dinning room, a desk top computer and the computer network and a couple of fans. All at the same time all day long. So these things put out a lot of power.. It is more like having a jar of dollars not pennies.

Go to this page and check out the how to for a grid tie or a grid tie with battery backup or even the off grid system how to's. And then read a lot more if you plan to do the install your self. Play it safe and learn what you are dealing with.

http://www.oynot.com/solar-info.html