Is solar still a good deal? As we now know, as of last October, no new applicants to Hawaiian Electric Co.’s net energy metering, or NEM, program will be accepted.

Under the old regime, if you could put up enough panels, you’d be able to pare your bill to under $20 a month. Not only that, the excess energy your system generated above and beyond your monthly bill would build up credits, which would compensate for nighttime use, inclement weather and shorter winter days when the system would not be as productive.

It was a terrific deal while it lasted.

The NEM program has been replaced by a much stingier energy buy-back program. Under the old program, HECO would credit the customer at full retail rate under a formula with a number of factors. The new program, Customer Grid Supply, pays only 15.07 cents per kilowatt-hour on the energy that you put back in the grid above your actual usage on Oahu. That means the credits are limited to your monthly consumption of energy, and any surplus produced will not carry over to the following month as it did with the NEM program.

Does that mean you should forgo getting PV at all?

Mike Tanuvasa, founder of Honolulu-based SolarTech Industries, says it still makes sense to put photovoltaic on your roof. The caveat is that you’ll need to combine your panels with separate products such as solar water heating and solar air-conditioning systems that don’t require approval from HECO.

Before installing PV, Tanuvasa suggests deploying a solar water heater, which could shave 30 to 40 percent off your electrical bill. The average cost for a unit is about $6,600, but after a $750 rebate and federal and state tax credits (35 percent and 30 percent, respectively), the net cost is only $2,047.

Another option to consider is a solar air-conditioning system. Something that will work with a single, 500-square-foot room will cost between $5,000 and $6,000. After tax credits the price comes to about $2,100.

If you wish to go ahead with PV, in addition to the existing solar water heater and AC components, it’s obligatory, says Tanuvasa, to do a daytime energy audit that will determine precisely how much energy you will need to produce to maximize your system. Oversizing your PV system is not recommended mainly because of the reduced buy-back rate in the new Customer Grid Supply program.

So how much will you save by combining PV and the other solar products?

Let’s start with the assumption that the electrical bill for the average three-bedroom house will be approximately $400 a month. If the customer’s daytime use is 12 kilowatts an hour, the customer would need eight to 10 panels, which would cost between $10,000 and $11,000. After tax credits your balance should be about $3,850.

Your former $400-per-month bill would now be about $150 per month, and you’ll have spent approximately $8,000 for your combined PV/solar water heater/AC system after tax credits and rebates.

The takeaway is that the best place to start, if you wish to go solar, is with a solar water heater. After that, start crunching numbers. The savings from the Customer Grid Supply program will eventually pay for your investment, but it will certainly take longer than the previous program.

Mike Meyer, formerly Internet general manager at Oceanic Time Warner Cable, is now chief information officer at Honolulu Community College. Reach him at mmeyer@hawaii.edu.