Hey Mana, no, the power company will not get "upset" with you for installing a few solar panels. They might fine you if you try to connect your equipment to their grid without their permission or required equipment, but they won't be upset. You have to take a good look at your bill one day to understand this. I don't know what your rate structure is, but if you're spending $400 for electricity in one month, your home probably uses 8 to 10 times the electricity ours does. Even if you turned everything off and used none, you would still get a bill, there are connection fees, taxes, and other items that are added on after the calculation is done for the amount of usage you have. The power company is happy to let you produce all your own power, and keep paying them the "fees" alone, they still get money from you.
We've been powering our home from the wind and sun for 12 years now, and on average our electric bill is around $ 4 to 10 dollars a month. Most of it is connection fees and taxes, usually our usage is around 2 or 3 dollars per month. They have not complained once to me about the situation. To produce that $40 or so in electricity that we used to use each month, we have a 1.4 kilowatt solar array, a 1 kw wind turbine, solar water preheaters, solar passive gain windows, rain water collection tank and a few extras. The cost for this equipment today might be around $10,000 if you installed it yourself. What I'm driving at is that the 280 watt panels and 500 watt inverter you mentioned is not going to save you "alot" of money, if it was hooked up properly and ran some loads in your home, you would probably save $5 to $10 per month, so your bill would only have been $390 instead of $400 recently. Your real problem is usage. We had the same problem 15 years ago. Back then we embarked on a plan to replace appliances, lighting and some electronics, and make some habit pattern changes as well. Leaving the back porch light on all day so it is on for the 12 seconds you walk in through that door at night for example, will take about another 150 watts of solar power, which might add $300 to the cost of your equipment. To put it another way, turning off the light saves you the 15 cents in electricity and $300 in equipment, what makes more sense to you?
Once we got our home pared down to just a few hundred units of usage each month, it was reasonable to add the solar equipment and wind turbine. Since then, our home has not been without power for even one minute, hard to put a price on that, but the solar equipment will never pay for itself in utility bill savings alone, it won't in your case either until you can cut back on the horrendous amount of power your home uses.
I also want to warn you about getting info about this from hacks like me online. I've learned that there are two things in vast supply in solar power, sun, and missinformation. It's amazing to me how many people are willing to offer advice on this subject who have never laid a hand on a solar panel or inverter. Check out some sources below and think about getting a subscription to Home Power Magazine, they know a lot more about this subject than the guys posting answers here. Take care, Rudydoo
Home Power Magazine, homepower.com
Midwest Renewable Energy Association MREA.ORG
Solar Energy International, solarenergy.org