The cost and benefit of solar energy?

Answer 1

Unless it is covered or disconnected, any number of solar panels would cut down your monthly electricity bill from the utility company. However, solar panels may well increase your effective electricity bill.

Renewables are tricky to calculate; solar panels have a "peak power" rating but you'll probably not achieve this. As well, where you are on the planet will affect how much sunlight you receive.

Rule of thumb: assume you will get 60% of the panels peak rating as a daily average. A 200 W panel would (by this RoT) give you 120 W of power. Assuming 12 hours of effective daylight (average over the whole year, dawn/dusk ) yields 12h * 120W = 1440 Wh. That is 43 kWH per month for a 200 W panel.

The actual number will vary...if you're in Phoenix or Madrid the number is quite a bit higher. If you're in Saskatchewan the number will be lower (particularly as you'll have to sweep snow off the panel in the winter!)

You'd then need to determine how many years you'll annualize your installed system cost over. System cost is not just the panel but also the installation labour, inverters, wiring, batteries, controllers, and (possibly) financing costs.

For rough numbers, let's assume that you installed ten panels with a total system cost of $20k [NOTE: fictional number for demonstration purposes only], and that you're going to annualize your cost over ten years.

• System cost = $20k = $2k/year = $167/mo.
• Above Rule of Thumb: 10 panels * 43 kWH/mo/panel = 430 kWH/mo.
• This gives you an effective solar price of about $0.39/kWH (in years 1-10).

So now look at your utility bills over the year: does the average exceed 430 kWH? Probably...so you're not likely to run the meter in reverse. But you would make a dent in the bill you receive every month.

And (here's the kicker): by this calculation your effective electricity bill (utility company plus your monthly "cost" for the solar system) is going to increase: you're probably not paying $0.39/kWH...more like $0.08/kWH in the US (here in Ireland I'm paying EUR 0.17/kWH = US$ 0.27/kWH).

The actual numbers in your case will probably vary. Talk to a solar panel installer and they'll be able to help you do more accurate calculations. BUT VERY IMPORTANT: be sure to get local references of installed customers and then talk to the references. The company wants to sell you panels so their calculations will be optimistic. Only people with similar systems in your area will be able to tell you what they are able to achieve in terms of panel efficiency and productivity.

One final point: in year 11 of the above scenario, your solar panels become "free" to operate. Except that:

1. Current panels have an expected lifetime of about 20 years
2. Panel efficiency degrades over time; peak power in year 20 is 50% of what it was in year 1.
3. Batteries will need to be replaced every 5 years or so.
4. Inverters and controllers can (and do) fail.

The net result is that year 11-20 you'll probably start needing to pay for maintenance and replacement costs...so it isn't likely to be free.

A far more cost-effective option to consider: solar water heating. System cost is lower, and instead of displacing electricity (in the US, mostly coal-based) you'll likely be replacing natural gas. In all liklihood, natural gas prices in the US will increase faster than electricity prices, so solar water heating is a more effective hedge.

Answer 2

Costs:

• Size of solar panels
• cost, installation, maintenance
• sun isn't always out

Benefits:

• renewable
• takes nothing from planet
• can be stored
• decreases air pollution
• constant supply
• reduces need for battery disposal

Answer 3

Solar energy is very expensive to manufacture and distribute, so not much money can be saved by using solar energy instead of fossil fuels.

Answer 4

Lets put it this way. In one year, you will have saved about as much money (with solar panels) as the solar panels costed

Answer 5

It depends how much energy you used before.

Answer 6

This question needs fleshing out - like all investment the benefits will only be available after the investment is repaid and then all gains are banked.