You mentioned "major conservation". If this is your way, and you want to avoid running generator completely or run it very occasionally - then in summer at your latitude the minimum array would be either 260-280W or 500-600W. And at least 200 AH battery - 2*6V @225 AH each will be it.
280W is the maximum for a simple install without complications of thick cable and roof junction box. 2*140W panels, 20A-25A PWM controller.
If you're thinking about future expansion - better do it now and forget 2*140W + PWM. Get two 250-280W and 45A MPPT controller. You can still get away without J-box then.
Unless you are in Az desert, you should expect rainy and cloudy days at times, and then 600W will harvest what 300W would on a good day. Or you park in partial shade. Or you have to run a furnace. A lot can be done to conserve energy, LED lights is not up to discussion. I replaced furnace with catalytic heater - silent, easy on propane and no 12V required. "Major conservation" may mean different things to different people. If you are running a fullsize computer tower and can't live without microwave several times a day, 1200W coffee maker and toaster - then you better cover the whole roof with panels.
