It depends on when you are using most of your electricity. Solar power here is connected to the grid. You pay extra for a special cut off switch to separate your units from the grid. If the grid goes off, so does your solar, unless you have that bypass switch. It is a safety precautions for the electrical workers so there is not so much juice in the lines from solar panels to electricute them.
Average system is about 20 panels. Average cost here $1000 per panel, but some places allow rebates. In the early days of solar here, between the electrical company rebate and the government rebate the net cost was about $2000. The rebates have ended and the electric company is now limiting the number of solar systems in each area. Max 10%. The have also altered the solar deal. Customers under the old deal are grandfathered in and they have an average bill of $17 a month. The new solar customers and customers who add panels to their old system are getting half the credit for the power their system generates during the day and an increase in what they have to pay for what they use at night. It is still less than someone without solar panels at all but more like $60 a month for them.
The newer systems are more efficient than the older ones but solar batteries are still new. Power cannot be saved so it goes into the grid and the meter runs backward. They will use their reserve power at night.
If you do most of your cooking, cleaning, washing, bathing, and running of power tools mostly in during the daylight hours you do have savings. Most people work during the day and when the solar power is generated and they use most of the electricity at night after the sun goes down. There isn't going to be a great advantage if you are off the grid and using power at night until they improve the solar battery technology which is coming. It does pay if you use most of your power during the day when it is being generated and you go to sleep early especially if you are off the grid. It depends on your lifestyle.
I don't use enough power to be worth having a system. The break even point is $140 a month. My bill is usually around $120 and I maximally conserve. I have timers on my two water heaters. I have 2 refrigerators and a chest freezer that use the bulk of the electricity. I do 3-4 loads of laundry a week in cold water and although I do use a dryer, I could save $10-$20 a month if I dried my clothes on the line. All of my lights except for a couple of closet lights are cfl and Flourescents and I hardly have them on. I turn them off when I leave the room and I sleep early so my house is literally in the dark on most days. I am even on the computer with the room lights off. I have the tv's and lamps I don't use unplugged. It saves me a lot of damage from power surges to leave them unplugged. Water costs more than electricity so I don't let the shower run when I take a bath and I save water from the shower and sink to flush the toilet. I use the electric range to cook breakfast, but I cook usually a stew, spaghetti, or casserole once every 4 days or so, and I cook a pot of rice with eggs once and I have boiled eggs and rice for the week. I don't like to cook after work, so I will eat leftovers heated in the microwave or open a can of beans and eat it straight out of the can for dinner, so I may not use the range for cooking anything more than breakfast for days.
The farm where I work has a couple of alternative energy systems. There is a windmill. it operates one small aerator.
Solar panels. It takes 2 solar panels to run one fan. I don't know how many panels it takes to run a pump but the solar panels on the roofs of the buildings supply about 60% of the farm's total electricity.
If you have enough wind and room, a wind turbine can generate electricity even at night. The wind farms here had the potential to generate clean low cost energy, but my opinion is that community opposition and strong opposition of the electric monopoly which did not want to buy power they did not own caused many of the operations to shut down. They could provide the power but needed to connect to the grid and the electric company did not want to pay them for the power they generated. The turbines were shut down because the blades could come loose and fly off. The turbines are on mountain ridges, all they might hit would be a cow and if the blades are maintained and tightened they should not pose a danger to anyone. Maui electric has the largest wind farm in the state and the local utility owns it. The wind farm in Kahuku on Oahu did not generate as much power because even though it was windy there, it was not steady enough to keep the turbines going. The turbine technology is also improving and newer ones are more efficient and need less wind to operate.
The life of a solar system is about 20 years. It will not generate full power for the entire time. Like storage batteries, they lose capacity over time and become less efficient. The panels have to be cleaned and inspected every 6 months. Usually the company here that installs the system has a service contract to do that. You have to have a pretty new roof to install a solar or hot water system on the roof. They charge to dissassemble and reassemble the systems if you have to do roof repairs. If you live in an area with high winds like tornadoes and hurricanes, check your insurance policy you may have to have additional coverage for damage to the panels. Solar water heaters don't store a lot of hot water for a large family and again, it is better to use the hot water in the day time. On cloudy days, the water may not be hot enough. Solar panels will generate less power on cloudy days, but they do still generate some power.
Happy gardening in Hawaii. Gardens are where people grow.