cost of PV

Sorry folks for straying so far off topic, please post your local solar costs. So far we have only two $5000/kw and $8000/kw before subsidies.

OK, I see that, we have some solar lights where it is expensive to connect to the grid. In that case they make perfect sense. Now connecting these lights as they are to the grid makes no sense, the solar panel is only 100 W, generating about 120kwh/year - if half was waste you could avoid by grid tying they might feed an extra 60kwh/year to the grid, but I doubt it is close to this much. It just doesn't make much sense to connect to the power lines add the synchronous inverter etc. Likely subsidies are maxed the way they are, and you get no more government money to connect it to the grid.

Now your idea was a good one though, say we designed a good looking solar light tree instead with a bigger say 250W solar array that was grid tied. The size of the panel of those lights was chosen for their operation, not to feed the grid. Proper design would use the biggest panel that was structurally and ascetically sound. If the light used 50W, then you are adding 200W to the grid, and can much better pay for the inverter and grid hook up. I looked at the jersey implementation and it was fairly ugly, but workable. I agree with some of your numbers that they are over paying. Part of the light savings are switching to more efficient led lighting that needs to be replaced less often saving maintenance costs. Austin has done this with traffic lighting but not yet with street lights.

The pole part is a low percentage of the cost. Perhaps replacing the entire street light with one designed to be grid tied is the most cost effective. Those solar/battery ones could be relocated to off grid locations. Old traditional AC lights designed for inefficient bulbs could be recycled. If you can design an LED + 250W solar street light for $1200 more than a sodium street light, payback is fast. Pulling out these old grid tied lights, and replacing them may be very cost effective indeed with all the energy savings and lower maintenance, you may be effectively doubling the efficiency and adding solar with a less than 5 year payback.

LED Streetlight's Price Cut in Half - WSJ.com

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It would be cool if instead of street lights consuming 1% of electricity, they produced enough to add 1% of electricity to the grid over their lighting needs.​