SOLAR: Solar Onpeak Load Alternative Resource

My parent's house is fitted with a grid interactive inverter which can pump any renewable energy back into the grid. Although they have installed their own power source based on solar panels, they have more inverter capacity than they can fill at the moment. What we offer is for people to buy small amounts of solar panels and use our infrastructure to generate their own renewable energy.

The current price of solar panels is $9 a watt, and we will sell any multiple of 0.5W.

News

Installation is complete. (photos)
All the 1.5kW have arrived.
We are now getting 1.5 kW of panel with seav subsidy. Half the panels have arrived.
150W has been installed.
150W of panel is now on order and should be here by feb. 75W panels turn out to be the most economical at the moment.

Story

When I first researched this project back in 1998 the idea was to build a single UPS system for for our extensive network of computers. Thus grid interactivity wasn't a priority. At that stage inverter technology wasn't readily available and so I got a 300W inverter from Jaycar electronics.

The inverter was set up with a relay to cut in when the mains failed. The storage batteries were 2×48RC 'standard' car batteries from Target. This system worked fine for 3 years, but eventually the inverter lost regulation and fried its high voltage side.

The Trace PS2524A Inverter

At this point I had seen more inverters around the place and thought about building a solar backup system (in the 3 years of running we had two summers where people weren't allowed to run computers during the day - I simply ran them off the batteries and recharged at night :)

Our needs were somewhat unusual from the point of view of inverter providers - we wanted both grid interactive, and at the same time, UPS capability. Most of the low end brands seemed to give only one of those two features. Eventually I settled on the PS2524A from trace - a 2.5kW 24V inverter which was designed for practically anything you could imagine. It was also cheaper than any of the competing brands of inverter by a few $1000.

The batteries were initially 2×48RC car batteries, but were replaced with some big trojan deep cycle gel cells.

After happily running the system for a few months I rang up to find out what had happened to the certification for grid interactivity. It turned out that the PS2524A/E was not going to be certified. This meant that the inverter couldn't be used in grid interactive mode. (We didn't have any solar panels at that point, so this was only a problem for we did, but as we bought the inverter expressely for its grid interactive mode we would have bought something much more expensive than necessary.)

The Trace SW3024A Inverter

Going solar organised the whole deal and we got a replacement SW3024E, which was certified, for the cost of shipping. (At first we were going to get to keep the old inverter, but I think Going Solar or BP realised that they could resell it to a farmer somewhere.) The SW3024 is a much beefier machine (3.3kW, with a higher peak output) and has a nice little lcd display on the front cover.

After running the system with 2×75W panels for several months we became convinced that with goverment rebates and the significant drop in panel price since we first looked, we could afford to put in a higher power version. Going Solar recommended a Mr Stephen Cook to install the system and he's done a great job.

The batteries are kept at float charge level by the PL60 solar controller and the inverter simply pulls enough current out to trick the charger into thinking that the batteries aren't full yet.

Current panel owners

Paul Harrison:	10W	total generated so far = 9.12kWhr = -??kg CO₂
Thorne Lawler:	75W	total generated so far = 90kWhr = -??kg CO₂
Charles Twardy:	75W	total generated so far = 90kWhr = -??kg CO₂

How it all happened: price calculations

United Energy Green was accredited as a Green Power product in May 1999 and is now available to all of their 520,000 Victorian customers. Subscribers pay an extra 3c per kWh for Green Power, thereby contributing around $3 per week (for an average household). Landfill gas is the primary source of Green Power for United Energy, however they are currently researching solar and wave power technology for use in the future.

Coal power costs 12.77cents per kWhr, making $9 a W, assuming 6 hours of sunlight on average each day, generating 2.2kWhr, pay off in 32 years.

Green power costs 16cents per kWhr, paying off in 25 years

It is also worth noting that there isn't enough green generation available for everyone to use it, and United Energy will probably start buying back solar power commercially in the next few years..

Notes from the wiz

From: wiz
Subject: solar sells

'evening..here's the sort of ting I have in mind...
[goofey -rc njh > tomail.txt and then mangled into shape]

Essentially, this system is a privately owned and run solar-farm.
The current plan is to have people to buy portions of panels and have this web page show how much power has been produced and how many CO₂ emissions have been reduced as a result.
An initial trial-run of several months will ensure that the system is reliable and viable. This period is necessary in order to collect operational data.
Rather than having a number of small setups distributed over a number of homes, the whole thing is hosted at a single location. This is advantageous as it means less maintainance and less opportunity for part of the system to fail as it is all centrally located.(njh: it also reduces one-off costs, such as inverter inefficiencies; single site increases risk associated with failure, but also increases speed of repair.)
It's a sound tactic for people in rental properties, as getting permission from the landlord for major works on the property is almost impossible. Dismantling and moving a rented home's solar array presents similar problems.
In financial terms, return-on-investment is a portion of what the energy company pays for buying excess energy (based on the proportion of an individual's investment in the scheme). Although this is a gradual payment, the total amount will add up over the years to be more than the initial cost.
What does the $4.50 per 0.5W buy? Besides a portion of a solar panel, it covers other hardware such as mounting bracket, wire, drop-out relays and so on. Any additional installation, maintaince and day-to-day running of the system is done at the time and expense of njh(he is the sad sort who enjoys this stuff).
Each person will be sent the money that corresponds to the power that their share of the equipment has generated over the time interval (quarterly? (njh: yes, probably keeping 1/100s of cents in the system and giving the maximum amount below that amount, keeping the error for next time)).
Shares are sold in multiples of 0.5W. Although that may appear to be a small amount, it allows people to contribute small amounts as they feel they can afford to. For example: an incremental share increase of 0.5W per fortnight might be easier to budget for than investing in several watts at once.
See http://www.csse.monash.edu.au/~njh/solar/ for more information, as well as a summary of subscribers and their energy quotas.

(is there anything I've missed? (besides getting the numbers to work))

Summary

In summary, it's effectively like having solar cells in your own roof, except:

Setup and maintainace and management of associated hardware and software is done by njh;
It is in a centralised location, meaning it does not matter if you are renting or wish to move; (The owners of the house plan to live there for at least 20 years, acts of god not withstanding)
Peak loads are handled by the grid, so there's no risk of getting a brownout from sustained periods of bad weather or malfunctioning batteries (an unreasonable fear spouted by opponents of solar power); The system doesn't require batteries to operate, they are actually only used for UPSing a computer room.
Changes will not need to be made to household wiring to use this solar power. Household equipment will continue to function normally, even demanding things like high start current devices (fridges are well known trouble makers in off grid systems, as they can draw many 1000s of watts for an instant, frying smaller solar systems). In reality households associated with this Solar Power scheme will continue to receive their energy by normal means, but this energy will be partly made up of the energy that their solar farm has generated;
Shares in the scheme may be increased or decreased on demand (Some kind of scheme will be set up to maintain fairness - if a panel has paid itself off, is there point in charging for it?);
Stakeholders in this scheme will be re-imbursed, pro rata, for their investment with the money made by selling energy generated to the energy company. Although the initial burden of establishing this system might appear steep, it will pay itself off in a number of years [njh: if the system is expected to compete on a watt/dollar basis, it will pay off in 32 years, if it is expected to compete with united energy's green power, it will pay off in 10 years]
Even discarding the previous point, this scheme is worthwhile from an environmental point of view. By committing to solar power, we are showing willing in reducing our dependence on non-renewable energy sources (such as brown coal and fossil fuels in general). This will reduce the amount of CO₂ being produced and lessen its impact on glabal warming.
The political message being generated by this scheme is in many ways more important than the electrical energy it generates. It is a step towards showing governments and the wider community that energy generated from renewable energy sources such as solar power is a viable alternative to non-renewable energy and that its long-term cost is significantly less in financial, and ultimately enviromnental, terms.

Finally, wiz says:

I seriously doubt it will take as long as 32 years to pay itself off. Energy prices will rise and the cost of solar cells will fall. My very rough estimation is fifteen to 20 years. Paul's view on the matter is that he's hoping some other alternative is invented/discovered in the meantime. It would be very pleasant to have this scheme "fail" for this reason (though that would count as a "success" based on the eighth point above)! :-> "Cost" and "price" are two very different things... I suggest adding a "how it works" section, saying that power generated is put into the grid, and that the energy company pays you/investors for this power. Effectively, it's like having solar cells in your own roof, except this way, (1) all the maintainace is done by you (njh); (2) it doesn't matter if you're renting or wish to move; (3) peak loads are handled by the grid, so there's no risk of getting a brownout from sustained periods of bad weather or malfunctioning batteries (an unreasonably large fear spouted by oppenents of solar power), (4, 5, 6, etc) other stuff... oh, and also, it's worth mentioning that people will be _paid_ for this venture, it's not just an exercise in funding your experiements! :) Couls help to dig up info on comparitave costs between * "normal" power bought from the grid; * your solar power bought from the grid; * power bought from the energy company when you speicfy that you want green energy (there is a surcharge for this and I'd be interested to see how it stacks up!). * returns on investment over time. Okay, that's the financial stuff out of the way. It's worth hammering home that this system is almost maintance-free (it _is_ for everyone except you), and that most improtantly of all, it's highly effieient and doesn't have a negative effect on the environment! (oh, and that it effectively pays for itself if one takes a long-term view and puts their money where their mouth is). Do the stats get updated automagically (that would be exceptionally cute), or is it one of those things that'll be calculated by hand and updated when each energy bill/return arrives? /--!>