A. There’s no physical connection between the home’s electrical system and the utility. You have an on-site power generation system, so you are your own utility. In my case, the sources are both solar and wind electric.

You store that energy in a battery pack for immediate or later use. Generally, those are sized for about three days of no power input — and generally, in three days you’ll have some power input.

But there are times, like in November, December and March, when you’re not generating enough. So you have to back up the whole system with a gasoline generator.

Q. Are we talking about do-it-yourself or professionally installed solar projects?

A. Professionally installed. We train homeowners and DIY people, but now 60-70 percent of people who go through program are in the trades. The systems are also being manufactured in ways that speed up installation for electrical and plumbing shops that want to offer this work.

Q. Where can one install a useful solar system?

A. For solar electricity, you need no shading from at least 9 a.m. to 3 p.m. every day of the year, and the sun’s position changes. Sometimes a roof is a suitable place. Sometimes a backyard, on a pole or on the ground.

Solar hot water, on the other hand, is very forgiving. You can have a little shade throughout the day with little or no impact.

Q. What are the investment costs and payback times for solar electric?

A. Before you install anything, you have to address energy efficiency. A homeowner could reduce electrical loads by 30-50 percent with energy-efficient measures. For every dollar you spend on energy efficiency, you reduce system cost by $3-$5.

A 4-5 kilowatt photovoltaic system for an average home would cost about $40,000 today, complete. After doing energy-efficiency measures, it would cost about $28,000.

Using $40,000, Focus on Energy would give a 25 percent rebate. A federal tax credit would knock off another 30 percent, for a final cost of about $21,000.

You’re still looking at a long time to pay off this system. But you can assume that each year the cost of energy will rise and value of dollar will decline.

The $28,000 system would end up costing you $14,700.

Q. What about solar hot water costs?

That stems both from a tax credit that Congress authorized last year as well as incentives from Focus on Energy and We Energies.

That doesn’t make solar power cheap, but it’s shortening the payback times for folks who are thinking about adding solar panels, said Michael Vickerman, executive director of Renew Wisconsin, a nonprofit group seeking to boost use of solar and wind power across the state.

We Energies of Milwaukee on Wednesday unveiled a new solar electric incentive after the old program basically sold out.

For more than two years, the utility’s incentive permitted customers to sell all of the renewable power generated by their home or business back to the utility at a high electricity price of 22.5 cents a kilowatt-hour. That’s nearly twice the amount We Energies charges to homeowners for electricity.

The new program amounts to an upfront payment to customers who install solar electric systems, said Carl Siegrist, senior renewable energy strategist at We Energies.

“It’s great news,” said Niels Wolter, who runs solar electric programs with the state Focus on Energy Initiative. “Probably the biggest thing is it helps people overcome that first cost, which is a big barrier, rather than paying people more over 10 years for the power.”

Instead of paying money each month to customers who install solar panels, the new incentive is upfront and based on the amount of power a home’s panels would generate during the first year.